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OSIRIS USER MANUAL - GTC - Instituto de Astrofísica de Canarias

1. 55 3 6 2 8 2 Preparing an observation checklist oec etre eth ree u susu Seb a 56 3 7 SPECTROPHOTOMETRIC STANDARDS FOR FLUX CALIBRATION 57 3 8 OSIRIS TUNABLE FILTERS GLOBAL 57 3 9 POST PROCESSING 58 ERN ACOMDIGHON TING COS uy 56 IILL c 58 m um nuna 58 3292 Nightskyemissi n ne TINGS ai 59 3 10 MEDIUM BAND IMAGING WITH TF ORDER 60 4 MEDIUM BAND IMAGING SHARDS FILTERS 63 4 1 PHOTON DETECTION EFFICIENCY WITH SHARDS FILTERS 67 5 FAS PINVIAGING MODES evt Re EE EIS 68 5 1 PAST PHOTOMBERY Yu au uy yas a ce a e ha aaa 68 2 2 FRAME TRANSFER za namn au aun 69 6 LONG SLIT SPECTROSCOPY aqa hui aa apus 71 6 1 ACQUISITION IN LONG SLIT SPECTROSCOPIC MODE 72 6 2 FEES UR 73 6 3 ERINGING u MM ELEM 73 6 4 SPATIAL DIS PUACE MEIN up a Shan ha a sa iy ap Lu a 74 6 5 ARC LINE MAPS 75
2. a aa 82 82 OPETAN CLG uuu yu i lu E 53 6 6 MPESJTS2000 R2500 GHOS TING Su op uu un ama 83 6 7 SECOND ORDER CONTAMINATION u u 84 Page 4 of 148 USER MANUAL 0 Date January 1 2014 6 8 SPECTROPHOTOMETRIC STANDARDS 84 6 9 SPECTROSCOPIC PHOTON DETECTION EFFICIENCY 85 7 MULTI OBJECT SPECTROSCOPY 86 7 1 tev tied oa am i yM 86 7 2 IOS EIER OC uuu 87 7 3 MOS MODE PRACTICAL 11 88 7 4 CALIBRATING MOS OBSERVATIONS s a D San 89 7 5 DESIGNING MOS MASKS A SUMMARY raa cod uuu tr cues Pee CHA ERE 89 7 6 MASK DESIGNER TOOL ase DL oe u Du ZL ss 90 AOT PROPRE THE 9 7 6 2 Getting to know the Mask eene nnns 9 203 aq 92 7 6 4 Designing MOS masks 97 7 6 4 1 Example 1 Using an OSIRIS pre Image 97
3. 8Z 8S T 9S 9r0r S 0 9 snay xni4 6000 7000 8000 Wavelength angstroms 5000 4000 OSIRIS R500B HgAr calibration lamp Ar lines 7635 106 Ar 8103 69 Ar1 8115 311 cvv less Iv Zr9 Pers VOL 8078 11 ccs 7928 11 987 108 MV Z6L 9008 5460 735 Hgl Iv 92181647 86 22Z 11 CSO PLSZ 698 007 11 186 8 7 11 9 6 C222 11 Z 2907 11 LET S969 99 0646 IBH 9696946 9S 9r0r S 0 9 8Z 8S T sav xni4 6000 7000 8000 Wavelength angstroms 9000 4000 Page 137 of 148 en gt lt Z lt 24 un Date January 1 2014 Ne calibration lamp OSIRIS R500B ION 99 G6T8 I9N 809 77 8 IPN 9C 00 8 I NGOY 9718 I9N 88572808 ION LI83V v6Z ZZ S SZ IHON L28 88 7 ION 668 8 TZ 9 ION 8 6 51194 I9N Z9t 6269 I9N Y0 2129 927 8299 e SEs I9N 228 CESS 19 865 9059 ION 8 9 9 ION 919 19 90 T 19 9 9 9609 9N 855 109 7032 413 Nel PES 265 IBN YE8 VV6S I9NS68 188S 9 887 CG8G 64021248 Ne sav xni4 6000 7000 8000 Wavelength angstroms 5000 4000 Page 138 of 148 en gt lt Z lt gt 24 un Date January 1 2014
4. Das 28 3 1 4 OSIRIS TF Characteristics and Features ies ete e e CI ERU 28 3 1 4 1 end due dete due dani 30 MEE 30 3 2 OSIRIS FOV FOR TUNABLE FILTER IMAGING 31 uuu u E a KE UM CH 32 0 200 Ple li m Q 33 3 3 OSIRIS TUNABLE FILTER AVAILABLE WIDTHS 35 3 4 ORDER SORTER FILTERS 37 3 5 CALIBRATING THE TF AND TUNING ACCURACY 37 mi imi Ee een u 37 Page 3 of 148 USER MANUAL 0 Date January 1 2014 qanun A EOS 37 3 95412 parallehzation procedure uu upay eet Bo Doe ex D d d En Dun alis dup B 38 Sule JLackorpatalleliStiicuecse eee eoque uen pu amaga a a e tb bcr a ERR AIR eR b FLUR tan UNIUS aa sya oe 39 22 41 3 5 2 General consider ny oe Glas ve n bs Ud on s e ado une 4 205 22 Calibration usine the ICM si uuu uu a etras etras usa 42 3 5 3 Checking the calibration by using night sky emission lines 43 3 CUM 45 DOS LUNN
5. 60 780 800 820 840 860 880 900 920 Wavelength nm Filtro f893bp50 Centro 100 780 800 820 840 850 880 900 920 940 960 Wavelength nm USER MANUAL 0 Page 128 of 148 Transmission Transrnission Filtro f302bp40 Centro 100 90 80 70 60 50 40 30 20 800 850 900 950 Wavelength nm Filtro 324bp34 Centro 100 80 80 70 60 820 840 860 880 900 920 940 960 980 Wavelength nm Transmission Transmission Date January 1 2014 Filtro 9196 41 Centro 100 80 80 60 50 40 30 20 820 840 860 880 900 920 940 960 980 Wavelength nm Filtro 827 bp34 Centro 100 80 80 70 60 820 840 850 880 900 920 940 960 980 Wavelength nm Filtro 9326 34 Centro 100 90 80 70 60 Transmission 95 ce 820 6840 860 880 90 940 960 980 Wavelength nm Figure 10 2 From left to right and top to bottom measured central spectral response of RTF Order Sorter Filters according to increasing wavelength for normal incidence Central wavelength and bandpass are indicated on top of each plot Page 129 of 148 USER MANUAL 0 Date January 1 2014 11 OSIRIS GRISMS VPH EFFICIENCIES Efficiency curves of the OSIRIS grisms VPHs have been measured during commissioning and are shown below These transmission curves include all the system telescope OSIRIS optics detectors OSIRIS R 300 R300B suc 0
6. entes 148 Page 5 of 148 USER MANUAL 0 Date January 1 2014 LIST ABBREVIATIONS fare GmideeweCmws LN Instituto de Astrof sica de Andaluc a IA UNAM Instituto de Astronom a Universidad Nacional Aut noma de M xico CM Instrument Calibration Module DT o Instrument Definition Team IFCA UNICAN Instituto de F sica de Cantabria Universidad de Cantabria Multiple Object Spectroscopy Mus C sm serons me bo mmm o SO W OV GTC IAA ICM IDT MOS NIR OS I SF QE S N TBC TBD TF Z Page 6 of 148 USER MANUAL 0 Date January 1 2014 1 INSTRUMENT CHARACTERISTICS 1 Overview 11 1 Instrument description OSIRIS is the first work horse imaging and spectroscopic Instrument for the GTC The OSIRIS acronym stands for Optical System for Imaging and low intermediate Resolution Integrated Spectroscopy which encapsulated in a few words the versatile nature of this instrument that we will describe in this manual A key scientific driver in the design of OSIRIS has been the study of star formation indicators in nearby galaxies and more distant objects back to the furthest observable galaxies with GTC In particular star formation in galaxies as a function of redshift is a classical topic and one main objectives of several current projects of instruments for large te
7. I9eNS68 1886 9 887 0686 IBH 99 062s IBH 8656945 7032 413 Nel S Z 09trS 8Z 8S T 059 5 xni4 8000 7000 6000 Wavelength angstroms 9000 4000 lamps ion HgAr Xe Ne calibrat OSIRIS R1000R I9N 8 099 9 6 66 0 6626 19 69 2916 leX cv ST06 lox ZOZ C668 lex LLY 6 88 86 222 11 9015694 I9N 668 8 rZ I9N Z9V SHZ 8 6 212 I9N 2976269 9 2899 N EYO 2 49 7 S6 86S9 ION 9059 IBN SZT ee 9N S6 99Z9 ION 6 919 I N 90 YLI 9609 ION 8551109 IN TES S 6S 9 9 6 9 6681885 IN 88 2685 99 0626 IDH 8656015 b nd CN e e 5460 735 Hgl snay xni4 7000 8000 9000 10000 Wavelength angstroms 6000 5000 Page 79 of 148 USER MANUAL 0 Date January 1 2014 OSIRIS R2000B HgAr Xe Ne calibration lamps 5 x 105 5460 735 Hgl 4 x 10 4358 328 Hgl 5400 562 Nel 3x10 f 8 Nel 94 Nel 9330 341 0 2 x 108 gt e N qm e 1x10 4046 563 Hgl 4500 977 4524 680 4624 276 5037 751 Nel 5562 766 Nel 5656 659 Nel 4000 4250 4500 4750 5000 5250 5500 5750 Wavelength angstroms Pag
8. instrument services and it is not thermally controlled but its temperature is quite stable The aim is to minimize temperature and humidity gradients within the instrument so as to ensure best image stability Even when inside the dome the humidity raises substantially due to wheather conditions the humidity inside OSIRIS is kept stable during several hours Temperature changes in GTC structure are transmitted quite fast by conduction to OSIRIS structure via the Nasmyth flange to the GTC rotator Also although the attached electronic cabinets are thermally isolated some heat leaks inside the instrument 1 2 Detectors 1 2 1 Description The OSIRIS detector system is composed of a mosaic of two buttable 2Kx4K CCDs to give a total 4Kx4K pixels 15 microns pixel The arrays are MAT 44 82 from Marconi 2 channel each Frame Transfer type 20 1000 kHz readout rate The software allows driving one or both MAT44 82 CCDs by one or two outputs each It is also possible to modify the parallel or serial clocks time so that it is possible to readout the array from 20 kHz per channel up to the CCD readout limit of 1 MHz It allows frame transfer mode and binning Page 13 of 148 USER MANUAL 0 Date January 1 2014 The following table summarises the main OSIRIS detector parameters Shuffle speed Used for skipping lines in window mode as well Readout speeds 20 50 amp 1 MHz possible not recommended 3 5e 100 kHz Nominal are 200
9. IDH ESS 0625 jr BH 906 6028 IBH S Z 09rS IBH 8z 8S r IGH 9 9r0r IBH 61 069 sav xni4 8000 9000 10000 7000 Wavelength angstroms 6000 5000 4000 HgAr Xe Ne calibration lamps OSIRIS R300R IBH S Z 09rS Secondorder l9X GL 666 19 02 6626 8819 411 Xel 09 c6r9 lex seg ezg 21 0868 86 Z 11 90162914 9 668 8 TZ Z9V SYCZ 1aN 9866 7032 413 Nel I9N 2976269 9 r0 2129 I9N 918199 I9N 56 86529 ISN C8 C S9 19 879 9059 Les 9 8pZ 2059 IN 9ZT 779 I9N 919 I9N 90 v 19 I NT S 6766 I N V 8 FF 6S IBH 99 062S IDH 8656915 5460 735 Hgl snav xni4 Megy sub Lair SN 887 2585 6000 7000 8000 9000 10000 11000 Wavelength angstroms 5000 Page 77 of 148 en gt lt Z lt gt 24 un Date January 1 2014 lamps ibration HgAr Ne cal OSIRIS R500B 86 11 9016292 ZZ IPN L28 88V7 6688674 Z9V Sy CZ gt IPN 8 6 ZL Z I9N 2976269 912999 n v0 69 I9N 66 8669 9 ZZ8 Z S9 8269059 8 099 oN zy veces ISN S6 9929 ION Y6S 919 9 90 919 9 919609 9N 8 F709 766 9 VE8 THES
10. 100 90 F 100 445 450 455 460 465 470 Wavelenath nm f458bp13 90 F T T T T T 100 450 455 460 465 470 475 Wavelenath nm f465bp13 90 F 1 1 1 l 1 100 455 460 465 470 475 480 Wavelenath nm 1473bp14 90 F 465 470 475 480 485 490 Wavelenath nm 96 Transmission 96 Transmission 96 Transmission 96 Transmission Page 121 of 148 Date January 1 2014 f454bp13 100 90 F 80 F 70 r 60 F 30 r 1 1 l 1 100 445 450 455 460 465 470 Wavelenath nm f461bp13 90 F T T T T T 100 455 460 465 470 475 480 Wavelenath nm f469bp 14 90 F 100 465 470 475 480 485 490 Wavelenath nm f477bp 14 90 F 80 F 470 475 480 485 490 495 Wavelenath nm Page 122 of 148 USER MANUAL 0 Date January 1 2014 f481bp14 f486bp14 100 T T T T T 100 T T T T T 90 4 90 3 80 E 80 70 4 5 5 60r 4 v 4 a a E E c 50 E n J 9 9 40 4 5 30 4 4 20 4 10 J 0 1 l 1 1 470 475 480 485 490 495 500 475 480 485 490 495 500 505 Wavelenath nm Wavelenath nm f490bp15 fA95bp15 100 T T T T T 100 T T T T T 90 4 90 6 6 a E E 9 9 9 9
11. HgAr calibration lamp OSIRIS R500R 9460 735 11 9822596 11 667 7276 11 796 2216 9000 11 rr6 2998 HV cry 1068 11 Zy9 Pers VOL 8078 Iv ccs 7928 HY HESLILS MV 69 0 8 982108 MV 2619008 Iv 92V 8T647 86 11 901 6 97 ZS9 MV 698 067 11 LZ 8000 11 9 6 C22 11 cro ZY HY 8LC 2907 11 LET 6969 7000 Wavelength angstroms 6000 DH 99 062S IBH 9656946 snay 1 1 HgAr calibration lamp Ar lines OSIRIS R500R e LO 8103 69 Arl 8115 311 Arl 11 98Z S96 11 66 6 11 29666 11 6 2998 lv cvv less 11 Zv9 Pers MV OLCS0y8 11 ccs v9c8 MY 987 108 27519008 11 92VL8Tv6Z quv 86 224 Iv CSO PLSZ 698 057 11 186 8 7 11 9 6 2224 Iv cvO rL Z Iv 8LC 2907 11 LET 6969 99 0646 IDH 9656946 S Z 09rS snay xni4 ie1iqiv 9000 8000 7000 Wavelength angstroms 6000 Page 139 of 148 en gt lt Z lt gt 24 un Date January 1 2014 Ne calibration lamp OSIRIS R500R T N IPN 67 6988 I N 198 5598 9 126 1898 IPN 5848 I9N 5 5598 19 ESE v C98 I9N ZF9 Y 98 9 9521659 I9N 9S S6r8 9 809 77 8 I9N 9C 00 8 I9SNS0T 9 18 I9N 86 T
12. Page 34 of 148 Date January 1 2014 USER MANUAL 0 A 3 8 3 20 where is the central wavelength tuned and r is the distance in arcminutes to the optical centre of the TF The expression for BTF is extremely accurate for any wavelength and radius Figure 3 8 Even at the edge of the 4 arcmin radius OSIRIS TF FOV the maximum error is of the order of the tuning accuracy 1 2 for all the wavelengths observed within the full BTF wavelength range For this reason no additional chromatic term 15 needed for the B TF Of course the two derived expressions for the BTF and RTF are different as the coatings and their thickness are different for both etalons and they are also wavelength dependent OSIRIS Blue Tunable Filter eo 9494 0 0 5 1 1 5 2 25 3 3 5 4 radius arcmin Figure 3 8 40 4 vs radius for different emission lines from the ICM spectra lamps covering the whole OSIRIS blue TF wavelength range The curve is the equation 3 20 The optical center for both TFs is located at pixel 1051 976 of CCDI including the 25 pixels of overscan That is within the gap of the CCDs and 2 pixels away from the right edge of the CCD1 or equivalently the center of the system lies at pixel 10 976 of CCD2 The wavelength observed with the TFs relative to this point changes following Equation 3 18 for the RTF or Equation 3 20 for BTF Users should be aware that the wavelength tuning is not uniform
13. 9 8872585 snav xn 3 4 5000 6000 7000 8000 9000 4000 Wavelength angstroms OSIRIS R300B Xe calibration lamp 88191411 Xel l9X61 666 9 026626 19X S 9 LESS snav xni4 8000 9000 10000 7000 Wavelength angstroms 6000 5000 4000 Page 134 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R300R HgAr calibration lamp 9460 735 Hgl 11 98 596 11 667 6 11 29666 11 vr6 2998 cvv Less 11 2 9 Pers VOL 8078 11 ccs v9c8 HV LHESILS MV 69 018 IJV 987108 LV 151 9008 92V 8T647 86 222 11 901 6 947 Iv ZS9 698 057 11 186 8 7 11 9 6 224 11 8LC 2907 11 LEY 6969 99 0646 9656946 snay 1 7000 8000 9000 10000 Wavelength angstroms 6000 5000 OSIRIS R300R HgAr calibration lamp Ar lines 10000 11 987 7696 R 11 667 72726 11 296616 9000 11 6 2998 lv cry Less 03 69 Ar17 8115 311 Arl 50111 2 9 8 MV 0LC 80v8 11 cce v9ca8 11 9871108 MV 2619008 HY 92181647 86 222 ZS9 PLSZ 698 067 HV 186 8 4Z 11 9 6 C2 4Z lv cvo Z 11 8L2 2904 11 LET 969 2990625 8656925 S Z 09trS 8000 4 e X w e M 7000 Wavelengt
14. IPA LATITUDE LONGITUD LOOPSHIF LST R500B 0001 GTC50 11B true 2348 33 34 OSIRIS 0 23 28762000 17877639 23 58 53 137 Date January 1 2014 required keyword must 1 GRISM identifier N A Observation Block N A Program Identifier N A Horizontal Binning Boolean Telescope height above sea level m MERE Ambient humidity U Percent 1n percent inherit keyword Boolean Instrument Mode N A Instrument Name N A Instrument position angle in degrees Degrees degrees latitude Degrees Telescope degrees 28 45 43 2 Telescope longitude degrees 17 52 39 5 Degrees Integer Local sidereal time HH MM SS h m s HH MM SS One data group Grism identification name duplicate value of FILTER4 Observing block number Unique observing program ID Whether binning was applied in the horizontal direction See also VBIN Telescope altitude above sea leval in meter Ambient humidity in percent Either T or F Whether extension hinerits keywords from primary extention not defined Unique instrument name Instrument position angle Telescpe latitude Telescope longitude Times charge displacement is repeated in charge transfer shaffling mode Local sidereal time USER MANUAL 0 Page lll of 148 M2RX M2RY M2UX M2UY M2UZ MASKNAME MJD OBS MOSAIC MOVTYPE NAMPS NAXIS NAXISI NA
15. Page 55 of 148 USER MANUAL V3 0 Date January 1 2014 the Images Figure 3 24 Alternatively instead of obtaining this extra images it 15 possible to correct them by multiplying by the appropriate factor gt 1 that can be easily calculated As a guideline the photometric accuracy that can be achieved as a function of the scan step 15 summarized in the table below Figure 3 24 6520 6540 6560 6580 6600 6620 6640 6660 6680 6700 6520 6540 6560 6580 6600 6620 6640 6660 6680 6520 6540 6560 6580 66 6620 6640 6660 Wavelength A Wavelength A 00 Wavelength A Figure 3 24 Theoretical examples of the band synthesis technique Left a scan step equal to the TF FWHM gives photometric uncertainties of 20 Middle a scan step 2 3 of the TF FWHM gives photometric uncertainties of 5 Right a scan step equal to half the TF FWHM gives photometric uncertainties of 2 The first and last images are either not used or corrected via the corresponding multiplicative factor Of course the images obtained can be used both for Tunable tomography and band synthesis For example in tunable tomography images can be combined in for example pairs or terns to increase S N in the case of faint targets depending on line widths and TF FWHM or all added together to serve as pseudo broad band image for target detection Examples of applications of this method are e Scanning the velocity curve of a large spiral galaxy comp
16. The OH atmospheric emission lines are observed through the TF as rings Figure 3 16 due to its centre to edge wavelength variation They are equivalent to the fringing observed in direct broad band imaging and like it are an additive effect They increase the background photon noise in the zones affected by the ring thus reducing the S N in these zones Sky rings not necessarily require correcting as long as the ring is not on the target and the target is not too faint Nevertheless if a correction is required there are several ways to proceed e the targets are not very large a superflat with the sky ring pattern can be obtained by combination of dithered and smoothed images even of different pointings 1 smoothing the dithered 1mages to be corrected using a kernel that wipes small scale structures sources but keeps large scale structures the rings obtain the media of the combined smoothed unmatched dithered images using a rejection algorithm the sources are not in the same position due to the dithering but the rings does since their position Page 60 of 148 USER MANUAL 0 Date January 1 2014 depend on the wavelength tuned only Even images of different pointings can be used as long as the wavelength tuned is the same 111 Subtracting the resulting superflat from the original images e Running for example SExtractor to remove sources thus creating again a superflat e Using specially devised programs
17. The effective available field for placing slitlets is about 7 5 by 6 arcmin At lower Resolutions R 300 R 500 the spectrum fits well within the available detector area and hence it 1s possible to observe the complete spectral coverage but within in a restricted region Users can place their slitlets in this restricted FOV where all the spectra will provide the complete spectral coverage of the grism see Table below At higher resolutions R 1000 2000 and 2500 a spectra will cover the whole detector length Therefore the spectral coverage is dependent on the position of the slit in the FOV and users should be aware of this when defining the observations In any case The Mask Designer Tool see Section 7 6 will provide information about the spectral coverage associated with each defined slit for higher resolution grisms VPHs R300B R300R R500B R500R Effective FOV To 2 9 3x34 75 XL 75 16 for complete spectral coverage Apart from the focal plane slit mask spectral observations in MOS mode are no different from normal long slit observations In principle MOS mode can be used with all grisms However the projection of the spectrum onto the detector is displaced in the dispersion direction in accordance with the position of each specific slitlet This implies that for slits close to the upper or lower boundary of the field part of the spectrum may be lost and in the case of higher resolution grisms the spectral window that falls onto t
18. c 0 85 a 6000 6600 7200 7800 8400 9000 Wavelength angstroms 9600 Figure 6 3 OSIRIS fringing vs wavelength obtained with the R500R grism Page 74 of 148 USER MANUAL 0 Date January 1 2014 The effect of possible wavelength drifts due to flexures in OSIRIS has been measured in order to evaluate its influence on the fringe pattern As a practical example for VPH R2500I which is the VPH most affected by fringing the fringing is doubled when a shift of 6 pixels is produced in the spectra while no noticeable effects are shown for shifts up to 3 pixels As instrument flexures causes displacements no larger than 1 pixel in the wavelength calibrations see section 6 2 the fringing in OSIRIS will not be affected by this Hence there is no need to obtain a spectral flat calibration taken with the same orientation as the science images In case fringing is of critical importance to reduce the fringing effect it is recommended to the user to use an offsetting pattern ABBA AB etc when observing at wavelengths larger than 9000 A and also for getting a better sky subtraction This strategy strongly recommended at higher resolutions VPHs R2500R and R2500I 6 4 Spatial displacement Upon inserting a VPH dispersing element into the optical train a small displacement between the target position in the acquisition image and the spectrum position in the spatial direction can be observed In OSIRIS only V
19. dark current level cross talk 14 dol Ouanna T ik 15 C GD u suu an 16 2 BROADBAND IMAGINEGCG 17 band a Qa Be 17 2 d PASEO du MICE AIME M E E MI UE 19 back qatu 19 2 1 1 3 COlOUE eeu i a catu t sinet 20 2 1 1 4 OSIRIS GTC Broad Band Imaging efficlIency 20 22 PHOTOMETRIC UNIFORMITY cccsscseccccsccscceccccsccscceccccscsccacsccssseccecscssssececcscssseees 22 2 3 SKY BLATTEIBEDS L L ots u umum ccc ais Pan ue id cU e ee 22 2 4 SLOAN PHOTOMETRIC STANDARDS uuu eto eet eis cbe t eda a od nte 22 3 TUNABLE FILTER IMAGING eee u ee ee sqa desea 23 3 OSIRIS TUNABLE FILTERS DESCRIPTION 23 3 1 1 Introduction to FabryPerot filters FPFs 23 3 1 1 1 Perttormance obanddeab FPE e eee EE i a ete PR 23 3 1 1 2 UTITUR 25 FREES e UE 26 CAE shi tem 28 DOES Order sO
20. ere 45 3 6 OBSERVING WITH OSIRIS TUNABLE FILTER cccccccccccccecccccccccecececcecceeecseeees 45 3 6 1 Tunable Filter vs Spectroscopy R u S A SS EEE EErEE EE 45 I0 fati E 46 3 6 2 1 Seleetine band esses u uu u oe petia odo ree encoded guru tide Fs pa 47 uk aS a naa 47 3622 DDeblendine linen au um a 48 3 6 2 3 da sm uu 49 3 6 2 4 Deciding target position and ortentation 50 3 6 2 5 Removing ghosts cosmic rays and cosmetics 51 220 2 5 Held a qaa 53 O25 2 AZimuthatditherine pateri s ei ostio ssn ies bra a uQ ad 53 2629F Punos pattern tr dl catio 53 3O20 TUNDE tono eee rete te o en etn cese Cor usa elias 53 FOLOL a inae duci kas 53 3621 Band synthesis technique su aun u D Z tn E 54 300 2 54 ae etel 55 3 6 2 8 1 Sources of instrumental photometric errors
21. never simulated SIMTYPE 0 SimulateType N A Should be always 0 Data are never simulated SIMULATE false Simulate active or Boslsan Should be always false Data are not never simulated SLITPA 0 Shoes Decrees Slit position angle in degrees j 5 from North toward east SLITW 1 Slit width Arcsec Slit width in arcsec Ambient I I 023 temperature Degrees Ambient temperature in Celsius Celsius degrees Celsius degrees Page 115 of 148 USER MANUAL 0 Date January 1 2014 TELESCOP GTC Telescope N A Telescope name TFBANDW 14 93255615 DE bu Sousa Tunable filter band width after z processing TFID RED TF identifier N A Tunable filter unique name TFTEMP E TF temperature x Tunable filter temperature filler wavelength TFWAVEL 8234 4411 Angstrom Tunable filter central wavelength after z processing TITLE ns pen Me N A Image title Duplicate OBJECT image 280 1049 1 2000 TRIM section Pixels ccd vignetted region Whether binning was applied in VBIN true Vertical Binning Boolean the vertical direction See also HBIN Wind direction WINDDIRE 177 from in degrees Degrees M id from north toward east from N to E WINDSPEE 5 96 Wind speed in m s m s Wind speed in m s 9 2 Astrometry with OSIRIS This section of the User Manual is devoted to explain how to perform a sub pixel precision astrometry of OSIRIS images from minimum header information The
22. 117 812901 11 LET 6969 99 0646 IDH 9656946 S Z 09rS 8Z 8S T 05 snay xnj4 6000 7000 8000 Wavelength angstroms 5000 4000 Page 141 of 148 en gt lt Z lt gt 24 un Date January 1 2014 OSIRIS R1000B Ne calibration lamp PLZZ SESZ HON LZ8 88 2 ION 668 854 I9N 2916724 7032 413 Nel IPN 86 51194 I9N 299 6 69 ION 0 129 I9N 922 999 i ION 56 8659 N ZZ8 Z S9 9N 8269069 ION 92v PEED 669 9929 ION 69 2919 I9N 90 tL9 ION 919609 I9N 855209 ION vES SZ6S 66 I9NS68188S 9 887585 o snay Aleuiquy 8000 6000 6382 992 Nel 7000 Wavelength angstroms 9000 4000 Page 142 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R1000R HgAr calibration lamp 5460 735 Hgl 10000 11 98 4596 667 VCC6 11 2967616 Iv cvv Less 11 Zv9 VCV8 VOL 8078 11 ccs v9c8 HV HESILS 999 018 9000 HY 26179008 MY 91 8r62 MV 86 22Z 11 901 6 947 vL6Z 698 067 Hy 186 8 7 11 926 224 11 8LC 2907 11 LET 5969 98Z YLO 8000 Wavelength angstroms 7000 6000 DH 99 0626 IDH 9656946 5000
23. 7 6 4 2 Example 2 Using equatorial coordinates 100 8 OBSERVING WITH OSIRIS u u y 103 8 1 EXPOSURE TIME CALCULATOR ETCOC 103 8 2 G IC Til ASE aa 103 9 OSIRIS DATA PROCESSING 104 GTC KEYWORDS 104 2 2 SASTRONEIRXWIJITOSIRISu ua auca oppeto dae uius atu 115 REID TD c O AA ENNER 116 SOLUTION u E k O 116 92 Mosaic Qa 118 9 2 4 Composing a first order mosaic from raw data 119 10 OSIRIS OS FILTER CHARACTERISTICS 120 LOT BLOU TONALE ipp a 120 JOO RED TUNABLE COLE IED Z uu P 125 11 OSIRIS GRISMS VPH EFFICIENCIES 129 12 OSIRIS INDIVIDUAL ARC LINE MAPBS 132 13 OSIRIS SLOAN PHOTOMETRIC STANDARDS 144 14 OSIRIS SPECTROPHOTOMETRIC STANDARDS 146 A LIST OF REFERENCE DOCUMENIS 148 REE aaa
24. OFF band OFF band Relative response Relative response 0 0 6540 6550 6560 6570 6580 6590 6600 6610 6620 6630 6640 6540 6550 6560 6570 6580 6590 6600 6610 6620 6630 6640 Wavelength Wavelength A Figure 3 17 Left A proper tuning of the off line wavelength minimizes contribution from your line to the continuum according to Equation 3 18 Right Increasing the FWHM of the off line tuning will require increasing the wavelength difference between on and off line wavelength tunings The distances are larger than expected since the TF spectral response has more wings than a standard interference filter 3 6 2 2 A Deblending lines Equation 3 25 can also be used for deblending lines Known the redshift one tuning for each line be observed From the line separation and the FWHMs of the tunings the contribution of the other lines to each tuning can be estimated and corrected simply via simultaneous equations system Page 49 of 148 USER MANUAL V3 0 Date January 1 2014 Ha 0 9F NII N Ha osL ON NII e o Relative response o o a 0 6540 6550 6560 6570 6580 6590 6600 Wavelength A Figure 3 19 Ha can be deblended from NII 658 4nm if the redshift or Doppler shift is known via defining a simultaneous equation system with TF transmissions derived from the TF FWHM and line relative positions 3 6 2 3 On line FWHM selection The TF FWH
25. TAN a o oe N A projection Must be written P Pre exactly as DEG Ga aneen System used for world coordinate CTYPE2 DEC TAN 3s s N A projection Must be written P exactly as Indicates whether the shutter i open or not inspite of the value DARK s CDD reported by If true the shutter did not open Data section in binned pixels DATASEC 26 1049 1 2051 Data Section Pixels pU QD overscan and binning Disply use it to show only data pixels 2012 02 file creation date Time stamp for fits file creation DATE 14T16 12 52 YYYY MM N A This is not the time of DDThh mm ss UT observation Time stamp relative to the start of 2012 02 Time when starts the exposure for charge transfer 14T16 12 16 632 the first exposure NS mode this refers to the first exposure Telescope Declination the telescope is DEC 63 41 39 856 declination DD PP SS aiming to In sessagesimal DD PP SS d m s degrees r Declination the telescope is DECDEG 63 6944043136059 declination in degrees P aiming to In decimal degrees degrees degrees Number of bytes used to DEEP 2 Bytes pixel bytes repre be DETECTOR Detectors Model N A Detector identification model 44 82 DETSEC 1 2048 1 4102 Detector Section Pixels in exposure DETSIZE 1 4096 1 4102 daging pixels Detector size in pixels Pixel Area Page 108 of 148 U
26. These stars should of course not be so bright that they saturate and they should all have a similar brightness A good choice is to have stars of about magnitude 18 in the r band but certainly not brighter than 17 as there will be a risk of saturation even with short exposure times They should not differ by more than 2 magnitudes in brightness Fainter stars can be used but exposure times will increase and hence also the overheads in aligning the mask Page 89 of 148 USER MANUAL 0 Date January 1 2014 Furthermore the fiducial stars should be well spread over the field and cover both CCDs We advise to have alignment stars covering both CCDs and span a distance of at least 4 arc minutes Slitlets for the science targets must not be narrower than 1 2 arc seconds and we advise users to design wider slits as this reduces the impact of any alignment error on the final signal to noise ratio of the spectra Having wider slits gives also more flexibility with respect to the seeing conditions and we strongly advice potential applicants to request reasonable seeing limits for their observation For reasons of efficiency and cost the observatory will not produce multiple masks for the same target fields for instance identical masks but with different slit widths Slits can be of any sensible length up to 24 arc seconds and may by tilted relative to each other for instance to position a slitlet along a certain orientation of a gala
27. as will be shown in the next points When you click on an entry in the list then the numbers in the other panels will display the details refering to the selected slitlet The Detector Editor 1s the most suitable visualisation tool to verify and possibly change the design of the mask made in pre imaging mode The Detector Editor panel shows the layout of the mask design superimposed on the pre image mosaic itself in the pixel coordinate frame Obviously the targets on the Image should align well with the slitlets Slitlets that for some reason are rejected by the MD tool show up in red When clicking on a slitlet in the image that slitlet entry will be highlighted in the image and it will be selected in the list of slitlets Slitlets can also be indentified by their pixel coordinates The description of target selection so far has been based on the user having generated a target list prior to using the MaskDesigner tool As an alternative object coordinates can also be generated within the MaskDesigner software itself by going to the Detector Editor panel and double clicking on the targets This automatically centroids the target seen in the image and adds that target to the list with the attributes slit size and shape wavelength range fiducial etc as they are set at that moment This is a very quick and easy method However we advise users to generate their coordinate list with trusted and well known tools such as IRAF Editing the p
28. dashed lines The phase difference arises because the first reflection is internal while all the other reflections are external with respect to glass On the other side of the cavity only constructive interference occurs At nonresonant wavelengths destructive interference occurs in the cavity and the first reflection dominates 3 1 1 2 Limitations It is apparent from the above equations that to obtain a higher resolution for a given order or to obtain a wider interorder spacing for a given resolution the finesse needs to be increased For a finesse greater than 100 a reflection coefficient R of greater than or about 0 97 15 necessary Equation 3 9 However so far we have considered the ideal situation where the plates are flat and parallel and the incoming light is parallel In particular Equations 3 1 3 3 3 5 3 7 and 3 9 refer to this situation using the subscript r to distinguish the results from a real filter In practice plate defects and the angular size of the beam limit the maximum finesse obtainable Page 26 of 148 USER MANUAL 0 Date January 1 2014 The effective finesse N is approximately given by l 1 1 1 3 11 N N N N where is the reflective finesse from Equation 3 9 N is the defect finesse due to plate defects and N is the aperture finesse due to the solid angle of the beam The defect finesse 2 3 12 2 d where is a length scale related
29. depending on Lower FWHM is limited by the order sorting filter and the higher by he etalon gap range Tuning time 10 ms depending on etalon gap Minimum is 1 ms Tuning accuracy in and FWHM 1 2 300 500 1 000 2 000 and 2 500 Resolution for 0 6 slit width Available spectral ranges R 300 amp 500 are limited by second order light and higher R by detector Long slit widths Masks of fixed widths from 0 4 through 10 0 arcseconds MOS masks 30 targets per mask using classical slits of 15 length or Several hundred using Nod amp Shuffle uShuffle or Flexures jLessthan pixel Tunable Filters Spectral resolutions larger than 500 a 5 x 6 arcminute FOV is recommended Physical gap is of 12 pixels binned or 3 arcsec the gap between photosensitive pixels is of 37 pixels or 9 4 arcsec Then the last quantity is the one to take into account when dithering for covering the gap on the sky Current IAC calibration facilities allow calibration from 450 through 950 nm only In the near future it will be expanded for covering the full OSIRIS wavelength range Dispersive elements grisms or VPHs can be rotated 90 for accommodating the spectra along lines or columns The nominal dispersion direction is along columns i e along the gap between detectors Beware of detector gap if rotating the disperser Page 11 of 148 USER MANUAL 0 Date January 1 2014 11 5
30. standard binned pixels in the OSIRIS FOV and Yo are the positions of the optical axis also in binned pixels The values for Xo Yo as well as the A B coefficients for each SHARDS filter are shown in the previous Table With those it can be possible to predict the expected wavelength observed with a SHARDS filter at any position in OSIRIS FOV Figure 4 2 690 685 CWL nm 580 radius aremin Figure 4 2 Central wavelength variation along the OSIRIS FOV for SHARD filter U687 17 showing the radial variation along the optical centre Xo Yo for this filter that can be fitted by Equation 4 1 The wavelength variation over the FOV also results in that the sky background is inhomogeneous This is in particular pronounced when strong sky lines fall within the band This makes that the sky background subtraction is a critical step in the reduction of data taken using SHARDs filters Page 66 of 148 Date January 1 2014 USER MANUAL 0 The following figures demonstrate this effect In Figure 4 3 left we have the wavelength variation for U687 17 filter in combination with a sky emission spectrum As it can be seen the stronger emission lines fall at the reddest wavelengths the ones that are observed in CCDI while these same lines are nearly undetected at the bluer wavelengths that are the ones observed in CCD2 This produces that the sky background will be notable different from one CCD to other being
31. 0 90 638 lt lt 671 1 10 Note that redwards of 65 1nm the can be used with higher efficiency and higher bandwidths When preparing TF observations it Is highly recommended to use the TF Setup Tool available within ETC section at http www gtc iac es instrumentation osiris php This tool allows to obtain the available widths for our wavelength of interest as well as to define the corresponding Order Sorter Filter that has to be used for the observation see Section 10 3 4 Order Sorter Filters The use of the tunable filters implies the utilization of order sorter filters OS in order to select the wavelength band that avoids confusion between different orders of interference of the Fabry Perot The observing wavelength defines which order shorter filter should be selected The available set of order sorter filters provides for a suitable filter for all wavelengths Order sorter filters overlap in wavelength but their working range ensures suppression of other orders The OS are tilted 10 5 degrees with respect to TF and grisms to avoid ghosts due to backwards reflections from the detector the TF is not tilted and therefore suffers reflections The description and characteristics for the complete OS filter set can be found in Section 9 3 5 Calibrating the TF and Tuning accuracy 3 5 1 Parallelism 3 5 1 1 General considerations TF parallelization consist in determining the X and Y values that keep plates parallel a
32. 25 R300R w 0 2 Efficiency e 0 1 0 05 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A OSIRIS R 500 0 25 R500B ws R500R w 0 2 Efficiency e 0 05 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenqth A Page 130 of 148 USER MANUAL 0 Date January 1 2014 OSIRIS R 1000 R1000B niii 0 2 Efficiency 0 1 0 05 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 4000 wavelenath A OSIRIS R 2000 R2000B uiii 0 25 0 2 Efficiency e 0 1 0 05 0 4000 4500 5000 5500 6000 wavelenqth A Page 131 of 148 USER MANUAL V3 0 Date January 1 2014 OSIRIS R 2500 0 3 R2500U nini R2500V R2500R 25001 S ay E 0 25 4 4 0 2 Efficiency k 0 1 A 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A Figure 11 1 From top to bottom overall efficiencies for OSIRIS grisms VPHs 1 9972596 _ 98 1596 amp IJV 66 6 J V 66v vZc6 amp E a lY 2962216 HV 96266 w 5 lt 6 1998 err LZS8 I HV cvv less a an E HY Zv9 vZV9 LV OLZ90y8 o lt HV 2 01278098 9 HV
33. 2808 I9N L8 T64Z IPN ZZ HHN L28 88v7 I9N 668 8 v7 I9N Z9 V SvCZ ION 866214 I9N 299 6 69 9 2129 918199 I9N S6 86S9 I9N 8 59 19N 8699069 I9N 8 0 9 VERON 5 9969 I9N VES 919 I9N 90 T 19 IPN 91 9609 I9N 8567 09 INT S SZ6S IPN VES V 6S 9 5681885 9 8872585 sav 1 9000 8000 7000 Wavelength angstroms 6000 lamp IOn Xe calibrat OSIRIS R500R 8819 411 Xel l9X61 666 I19X07 6626 l9XS9 2916 19X GY SY06 lex ZOZ C668 lex L6L 6078 lex 21170828 IPXECS8 PEs 19X S 9 LESS snav xn 3 7000 8000 9000 Wavelength angstroms 6000 Page 140 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R1000B HgAr calibration lamp e m e 86 022 11 90162914 Iv PLSZ 09805 11 186 8 47 11 9 6 C222 Iv cyo rl 11 9 2907 11 LET 5969 99 0646 IDH 9656926 8Z 8S T IBH S 05 snav xni4 6000 7000 8000 Wavelength angstroms 9000 4000 OSIRIS R1000B HgAr calibration lamp Ar lines 7635 106 Arl 86 622 CSO PLSZ 698 05 HV 186 8 Z7 11 9 6 2224 Iv rL Z
34. 545 550 525 530 535 540 545 550 555 Wavelenath nm Wavelenath nm f542bp18 f548bp18 100 T T T T T 100 T T T T T 90 4 90 4 80 4 80 4 70 4 70 4 96 Transmission o T 1 96 Transmission T 40 4 40 4 30 4 30 4 20 4 20 10 4 10 0 1 1 l 1 0 1 1 1 l 1 530 535 540 545 550 555 560 535 540 545 550 555 560 565 Wavelenath nm Wavelenath nm f554bp18 f561bp19 100 T T T T T 100 T T T T T 90 4 90 4 80 4 80 70 4 70 5 5 5 60r J 60r 4 a a 9 50r 1 8 50 9 9 40 40 4 5 5 30 4 20 4 20 10 4 10 4 0 L 1 l 1 0 1 1 l L 540 545 550 555 560 565 570 550 555 560 565 570 575 580 Wavelenath nm Wavelenath nm Page 124 of 148 USER MANUAL 0 Date January 1 2014 f568bp19 f575bp19 100 T T T T T 100 T T T T T 90 4 90 4 80 80 70 iz 70 60 F 60 F 96 Transmission 91 T 1 96 Transmission T 40 4 40 30 4 30 20 4 20 10 4 10 0 1 1 1 l 1 0 1 1 l 1 555 560 565 570 575 580 585 570 575 580 585 590 595 600 Wavelenath nm Wavelenath nm f583bp20 f591bp21 100 T T T T T 100 T T T T T 90 F 4 4 80 4 70 4 5 5 5 60r D 4 a a E E 50 9 al g g 40 4 5 5 4 20 4 10 4 0 1 1 l 1 0 1 L 1 l 1 570 575 580 585 590 595 60
35. 9 568 885 I N 882585 IBH 99 0625 IDH 86969785 7032 413 Nel e m e D IBH gze g8ser 9S 9r0r snay XN 4 7000 6000 9000 4000 Wavelength angstroms lamps ibration HgAr Xe Ne cal OSIRIS R500R S Z 09trS Secondorder 9 6 66 19X 076626 lex LLY 6 88 ION 09 G6T8 ION 809 77 8 ex ceo Lez o P X 0868 86 622 11 9045694 I9N 668 8 vZ 8 6 212 9 2916269 927 8299 270 2129 2282259 9N 8259089 88 556 8659 ON Eve CION seres I N 96 96 9 I9N T6S 919 19 90 r 9 9 91 9609 19 8 V 209 I NT S SZ6S IPN FES Vr 6S I9NS68 1886 19 88P C686 IBH 990615 IDH 8656915 I9N Z9V Sv CZ 7032 413 Nel 5460 735 Hgl snay xni4 8000 9000 10000 11000 7000 6000 Wavelength angstroms Page 78 of 148 en gt lt Z lt gt 24 un Date January 1 2014 lamps ibration HgAr Ne cal OSIRIS R1000B 86 11 9016292 ION 668 8 v4 79V Sy CZ A IN 8 6 Z1Z 9 297669 lI N t0 1L29 I N 9278199 9N S6 86S9 ION 825 9069 8VC COWS SN 97 I9N S61 9929 I9N PES 919 I9N 90 v19 I9N 91 9609 I9N8 F209 I NT S SZ6S I9N YES Vv 6S
36. Field obscuration and vignetting As can be appreciated from Figure 1 4 there is an obscuration of the left hand side OSIRIS full FOV of CCDI due to the edges of the filter wheels and the fold mirror This was contemplated in the original design and does not affect the specified unvignetted field of view The obscured area is best avoided although reliable photometry can be performed on targets located in this region of the detector Some vignetting is present in the lower part lower 250 pixels binned of the CCDs due to filter wheel 1 With the filter in position removed the vignetting is reduced in CCDI only Figure 1 4 In all cases the total unvignetted field of view 15 7 8 x 7 8 arcmin Figure 1 4 OSIRIS image showing the shadowing produced by the folder flat and filter wheels on one side of CCDI left Since the instrument is off axis the centre of the OSIRIS field does not coincide with GTC pointing centre Figure 1 4 shows the location of the standard pointing positions for the different observing modes of OSIRIS Broad Band Imaging 1 Long Slit Spectroscopy 2 and Tunable Filter Imaging 3 The location of the Tunable Filters optical centre and the MOS reference pointing are also shown 1 1 6 Field orientation and gap The OSIRIS instrument position angle within the GTC reference system is 150 540346 With this orientation North is up and East left in the images This value can be retrieved fron KEYWORD IPA at ima
37. PASP 96 530 Oke 1990 AJ 99 1621 Page 148 of 148 USER MANUAL 0 Date January 1 2014 A LIST OF REFERENCE DOCUMENTS Lauer amp Vald s F 1997 NOAO Newsletter 52 http www noao edu noao noaonews dec97 node23 html Vald s F 2000 Mosaic Data Structures http iraf noao edu projects ccdmosaic The Zen of IRAF A Spiritual User s Guide to the Image Reduction and Analysis Facility for the LINUX Novice A Charles Pullen A User s Guide to CCD Reductions with IRAF Philip Massey February 1997 B REFERENCES e Castro FJ et al 2007 Optical Data of GTC GTC Internal Report e Cuillandre et al 1994 A amp A 281 503 e Hiippenko 1982 PASP 94 715 e Francis P J Bland Hawthorn J 2004 MNRAS 353 301 e Gonz lez Serrano et al 2004 Experimental Astronomy 18 65 e Jester S et al 2005 AJ 130 873 e Jones Shopbell Bland Hawthorn 2002 MNRAS 329 759 e andolt A U 1992 AJ 104 340 e P rez Gonzalez et al 2013 ApJ 762 46 e SESO 2006 Collimator Unit Measurement Report e Smith et al 2002 AJ 123 2121 e Szokoly 2005 A amp A 443 703 e Veilleux S et al 2010 AJ 139 145
38. USER MANUAL V3 0 Date January 1 2014 Elevation at start of Telescope elevation at start of ELEVAT 47 3367634069994 Degrees observation observations END N A Marks end of image header EQUINOX 000 Epoch of the mean Equinox for world coordinate equinox for WCS system Exposure mode could be EXPMODE UNIQUE ExposureMode N A UNIQUE FORWARD START y FORWARD RETURN Exposure time Differ form EXPTIME 6 5 pum Seconds ELAPSHUT because of shutter seconds flying time EXTEND None N A Mark end of fits header extention Extension name according to EXTNAME 1111 Extension detector been read readout mode and readout channel FILSTAT COMMITED None N A Not Used FILTERI _ OPEN Biter identne Position of filter wheel 1 wheel 1 FILTER2 Position of filter wheel 2 wheel 2 FILTER3 ni Position of filter wheel 3 wheel 3 FILTER4 R1000B eee ROU GA Position of Grism wheel identifier FRAMESI 8606008 d Suet date Frame Frame type RDI modo simple FRAMETY Type 1 RDI 2 RDS RDS modo shutterless RDW 3 RDW modo frame transfer GAIN 1 18 Gain e adu Electrons ADU in electrons per ADU Gain requested by m T GAINTYPE GAIN x4 75 N A String identifying the gain mode user Page 110 of 148 USER MANUAL 0 GCOUNT GRISM GTCOBID GTCPRGID HBIN HEIGHT HUMIDITY INHERIT INSMODE INSTRUME
39. Y 992 to 1000 all binned coordinates There are no problems for the line identification as the intensity of the ghost 1s far below the average of the counts for the spectral lines However users must be aware when obtaining the flat fielding correction in the pixels range described above and only for R2000B R2500U and R2500V In the science Images the effect 1s irrelevant for the complete set of the average ratio between the ghost intensity and the integrated flux from the target that causes the ghost is on the order of 10 The ghost in science images can be noted as a focused image from the target in the other CCD see Figure 6 5 Figure 6 5 Two examples of OSIRIS VPHs R2000 2500 ghosting corresponding to R2500V left and R2500R right The focused image from the target a bright standard star can be observed in the opposite CCD respect to the spectra location being much more fainter in the case of R2500R Page 84 of 148 Date January 1 2014 USER MANUAL V3 0 6 7 Second order contamination the OSIRIS red grisms VPHs R300R R500R R1000R R2500R and R2500I are used in combination with an spectral order shorter filter GR which cuts out the light blueward from 495 nm However there is a slight contamination in the spectrum due to the second order as the spectral order shorter filter doesn t block completely the contribution for wavelengths lower that the defined cut level see Figure 6 1 Hence
40. Zeropoints From the observation of standard stars the following average zeropoints 1 ADU s at AM 0 and extinction coefficients have been measured those average values correspond to the period March 2010 December 2013 Zero point Extinction Filter mag mag airmass 25 79 40 09 0 47 20 01 g 28 82 0 07 _ 0 16 20 0 With those zeropoints instrumental magnitudes can be obtained directly using the formula m Z 2 5 logio Flux ADUs s k X where standard extinction coefficients for the can found at http www ing 1ac es Astronomy observing manuals ps tech notes tnO3 1l pdf The zeropoints have been measured at the standard GTC pointing for Broad Band imaging that 1s placed at OSIRIS CCD2 Zeropoint values for CCD1 are on average 0 1 0 12 mag smaller in each filter than these The zeropoints are measured during photometric sky conditions Clouds or dust in the atmosphere will reduce the limiting magnitudes on average in spectroscopic nights we measure up to 0 3 0 5 mags of extra extinction Likewise changes in the cleanliness and transmission of all optical components will affect the zero points An updated version of the daily zeropoint values can be found at http www gtc iac es instruments osiris media zeropoints html 2 1 1 2 Sky background Estimates of the sky brightness ADUs s pix measured at a Elevation 55 deg in the standard OSIRIS Broad Band imaging mode 200
41. a unique run number the date instrument and observing mode as follows lt number gt lt date gt lt instrument gt lt mode gt fits For example 0000007448 20090703 OSIRIS OsirisBroadBandImage fits Here is a complete list of available OSIRIS observing modes the observing modes marked in red are not available yet OsirisBias OsirisBroadBandImage OsirisTunableFilterImage OsirisDomeFlat OsirisLongSlitSpectroscopy OsirisSkyFlat OsirisMOS OsirisSpectralFlat OsirisFastBroadBandImage 5 amsa wawam o Temm m OsirisFrameTransferLongSlitS pectroscopy The following table provides a listing and description of the OSIRIS FITS headers Please note that the complete list will be upgraded and the latest version can be found at http www gtc iac es instruments osiris media osirisFitsDictionary html Page 105 of 148 USER MANUAL 0 Name AGIARM AGIFOCUS AGITURNT AIRMASS AMPNAME AMPSEC APPLYPRE ARCHID ASGDEC ASGRA AZIMUTH BIASSEC BITPIX BSCALE BZERO Value 90 375 43 17 37 123 12 CCD_1 Left 1 2048 1 4102 true 175464 62 16 21 821 12 37 36 550 166 983854397316 5 22 5 2051 16 32768 Date January 1 2014 Description Units ASG arm position degrees ASG focus position mm ASG turn table HP degrees position AIRMASS N A Name of the amplifier used during readout AMP Section Pixels Reordering applied N A
42. as can be appreciated both from the maximum intensity and symmetry Non symmetric intensities are suspicious of lack of parallelism Page 42 of 148 USER MANUAL 0 Date January 1 2014 3 5 22 Calibration using the ICM The calibration procedure using the ICM has already been described within the parallelization procedure of the previous section An accurate wavelength calibration can be obtained only after parallelization i e determining the best XY values for the given range of Z and wavelength Wavelength calibration depends at least of the following Humidity This is potentially an important factor but since the instrument is flushed with dry air its effect is for practical purposes insignificant Temperature This produces a highly non linear effect where the etalon undergoes several phases of different variations ET 100 are quite large and take up to three hours to stabilize versus temperature changes However this is not as serious as it seems since implies only calibrating more frequently depending on the history and the temperature gradient It has been demonstrated to be safe operating with TF temperature gradients of at least 0 6 C hour produced by temperature differences between TF and telescope of several degrees as long as calibration is checked every 20 or 30 minutes When the temperature gradient 15 of the order of 0 1 0 2 C hour the tuning can be considered stable for at least one hour Telescope grad
43. button Three of them activate the main graphical representations of the current mask design the Detector Editor DE the Mask Editor ME and the Sky Editor Page 94 of 148 USER MANUAL 0 Date January 1 2014 SE that allow the user to view the same slitlet configuration in the three different coordinate systems The graphical display for these views employ the JSky tool Figure 7 4 shows as an example of the Detector Editor view The green rectangular outline shows the OSIRIS detector while the yellow box indicates the mask area that 15 available for placing slitlets Each of the visualization modes show these same outlines Detector Editor pre imaging mosaic File View Go Graphics T ls EUER ux smao Figure 7 4 Example of the Detector Editor view 06 51 24 997 41 28 07 11 J2000 The visualization options maintain many of the facilities provided by JSky For example the Sky Editor may be used to load images or catalogues either locally or remotely The Detector Editor by default shows an engineering image that indicates the useful area of the OSIRIS field but in case of designing a mask using an OSIRIS pre image this image will automatically be projected onto the Detector Editor view as show in the Figure 7 4 The Mask Preview button gives a view of what the physical mask will look like The fifth button Delete Slit deletes the selected slitlet that
44. dependence with location is larger There are several ways to alleviate this problem that will be described in the following Page 53 of 148 USER MANUAL 0 Date January 1 2014 subsections But note that in many cases ghosts do not required to be removed since they can be seen only for very bright sources 3 6 2 5 1 Field masking Inserting a focal plane mask that covers half the field and hides detector CCD1 avoids ghosts coming from that part of the field In this case dithering is not necessary to detect ghosts But obviously in this case only half the field can be used and therefore normally not an attractive option 3 6 2 5 2 Azimuthal dithering pattern When only one relatively small source is of interest the dithering can be done following the circle of equal wavelength 3 6 2 5 3 TF tuning dithering pattern If several relatively small targets spread on the FOV are to be observed it 15 possible to do a three point dithering where the TF tuning is changed to minimize wavelength variations at the edge of the TF FOV in one direction Then different sections of different images can be combined This is valid only when using tunable tomography 3 6 2 6 Tunable tomography 3 6 2 6 1 Technique Tunable tomography or TF scanning consists of obtaining a set of images of the same pointing at different consecutive wavelengths Figure 3 23 The characteristic parameters are e Initial and final wavelength or Z e Step in
45. exposure times allowed depending on both the readout speed and window size It can be noted that for decreasing a window by half of the size of a previous one the exposure time is not decreased exactly in the same proportion as the time for skipping the rest of the pixels increases Also for very small windows the skipping time dominates and the minimum exposure times are nearly the same for both readout speeds as the skipping time 15 the same independent of the readout speed Detector Area 200 kHz 500 kHz Full G5 x35 45s 05x08 There are a lot of possible combinations depending on the desired FOV and sampling requested Due to the high flexibility and the multiple possible combinations in using this observing mode Frame Transfer in OSIRIS is only offered in visitor mode Prior to defining your observing proposal it is strongly recommended to contact GTC staff astronomers to evaluate the optimum mode of operation Page 71 of 148 USER MANUAL V3 0 Date January 1 2014 6 LONG SLIT SPECTROSCOPY OSIRIS facilitates long slit spectroscopic observations A selection of 7 4 long slits of different widths are available which in combination with a selection of dispersive elements in the collimated beam provides for efficient low to medium resolution spectroscopy Available slit widths are 0 4 0 6 0 8 1 0 1 2 1 5 1 8 2 5 3 0 5 0 10 0 OSIRIS has a wide variety of grisms and volume phased holographic grating
46. filter set corresponding to OSIRIS Blue and Red Tunable Filters 10 1 Blue Tunable Filter Filter ID f451 13 454 13 458 13 461 13 465 13 469 14 473 14 477 14 f481 14 f486 14 490 15 495 15 499 15 1504 16 1509 16 514 16 519 16 nm 450 7 454 3 457 9 461 5 465 1 469 0 473 1 477 2 481 4 485 6 490 0 494 7 409 5 504 2 509 1 514 0 519 1 FWHM range nm 13 1 13 2 13 3 13 4 13 5 14 0 14 1 14 2 14 4 14 5 15 1 15 2 15 4 15 5 15 7 15 8 16 5 nm 448 458 458 461 461 464 464 468 468 473 473 476 476 481 481 484 484 489 489 494 494 498 498 503 503 506 506 511 511 516 516 522 522 528 Filter ID 525 17 530 17 536 17 542 18 548 18 554 18 561 19 568 19 575 19 583 20 591 21 599 22 608 22 617 23 627 24 638 25 nm 524 6 530 1 535 7 541 6 547 8 554 1 560 8 567 9 575 0 582 6 590 5 599 0 607 9 617 4 627 4 638 0 FWHM nm 16 7 16 8 17 0 17 8 19 0 192 19 5 20 4 20 7 21 8 211 255 293 25 0 TF X range nm 528 533 533 538 538 543 543 550 550 556 556 562 562 569 569 576 576 584 584 593 593 600 600 610 610 618 618 628 628 638 638 649 96 Transmission 96 Transmission 96 Transmission Transmission USER MANUAL 0 f451bp13
47. instructions are given in an example oriented fashion As mentioned in Section 1 1 the instrument contains a camera composed by a mosaic of two CCDs arranged along the largest dimension with 4192 x 2098 physical pixels each however throughout this section of the Manual any reference to pixel coordinates is given in the standard binned operation mode of OSIRIS A fits image extensions 1 and 2 with 2 headers plus a zero extension header 15 generated for each detector reading Both non zero extensions include information about the telescope pointing expressed through the keywords RA and DEC provisionally with identical values in all headers The projection of the telescope optical axis on detector 1 roughly coincides with the pixel 462 5 995 If the position angle of rotator header keyword IPA is 150 54036 degrees the images are oriented with North up East left At first order the mean plate scale is 0 254 arcsec pixel binned and the physical gap between CCDs 15 12 pixel wide Additionally the CCD2 15 shifted in 2 pixels with respect to CCD1 in the positive Y direction Page 116 of 148 USER MANUAL 0 Date January 1 2014 9 2 1 Input Data As initial condition individual extension frames to be astrometrically calibrated must be corrected for zero level including overscan and flat field e Construct an input source catalog with logical positions of astrometric sources preferably point like objects by usin
48. of the abovementioned action buttons open visualization windows where the mask design can be seen Each slit that 15 defined 15 shown in these window together with the associated band that will be occupied by the spectrum corresponding to the dispersive element and wavelength range chosen The three windows provide a view of the slits in equatorial sky coordinates for the Sky Page 96 of 148 USER MANUAL 0 Date January 1 2014 Editor detector coordinates for the Detector Editor and physical mask coordinates for the Mask Editor These windows are interactive to some extend can click on a slit upon which it will be highlighted as selected At the same time on the main window that same slit will be selected and its properties can be selected Changes in its properties are instantly reflected in the visualization windows Conflicting slitlets that are rejected are shown in red Through the Detector Editor the Sky Editor and the Mask Editor one can also define new slits by double clicking on the location where you want the slit to be However it is advisable to prepare the target list using other tools such as IRAF and importing such list into the MaskDesigner When using the MaskDesigner visualisation windows to define slits one must be aware that the definition will be on the basis of the coordinate system relevant for the window 1 9 pixels coordinates for the Detector Editor Log window The log window ess
49. on the scientific program the line to be observed the type of target its size velocity field or velocity dispersion redshift of Doppler shift accuracy of this shift and the number of targets it is necessary to determine Position of the target s in the FOV Orientation of the detector on the sky Wavelength to be tuned in the centre of the TF Dithering pattern to be used Technique to be used single exposures shuffled images fast photometry TF tomography or band synthesis FWHM to be used Use calculator for exploring possibilities This might drive reconsidering the technique to be used if FWHM is too narrow Wavelength range to be scanned for TF tomography or band synthesis Exposure time Use of TF OS or broad band filters for continuum subtraction Page 57 of 148 USER MANUAL 0 Date January 1 2014 3 7 Spectrophotometric standards for TF flux calibration The TF flux calibration 15 done using standard spectrophotometric stars as usual using the same settings as for obtaining the science data that is an image from the standard star at each of the wavelengths and with the same TF FWHM used for obtaining the science images The TF spectrophotometric standard is observed only under user request and a corresponding Observing Block has to be completed for this purpose The complete list of spectrophotometric standard stars for TF flux calibration can be found in Section 12 They are the same that ar
50. snay xni4 ienigav OSIRIS R1000R HgAr calibration lamp Ar lines 9460 735 11 98726596 LY 667 72726 296616 11 rr6 2998 HV CrP Less 11 2v9 Pers VOL 808 11 ccs v9c8 58 HY 9008 11 9218167 1 IJV 901 6692 86 222 ZS9 HLG 698 067 HV 186 8 47 11 9 6 cro 11 8C 2907 11 LET 6969 HV LESLLS MV 69 11 984 0 L DH lt 99 06 6 9696946 snay xn a3 Aie1liqivy Wavelength angstroms Page 143 of 148 USER MANUAL 0 Date January 1 2014 OSIRIS R1000R Ne calibrationlamp 7032 413 Nel 6402 248 Ne 8654 383 Nel 8655 522 Nel D Nz O d E 2 m3 2 E oooc 77 A Z 2222 s El S SISS en i gt lt o d io doo Z z E am E W gt En N e Qr co o 55 2 2 22 5 lt 2 yr ___ 2 _ a os ono OO 2 z 0220 n Mm cO M SeN K 5 be q KO Ps 8a F Des Oo d 12 5000 6000 7000 8000 9000 10000 Wavelength angstroms OSIRIS R1000R Xe calibration lamp 8819 411 Xel oD gt lt K e lt e N PT eo E S x gt um E LL _ gt x 28 o P Qu N OQ QU o ha a3 S z NP Do RE
51. the range of available FWHM are quite limited if a certain photometric accuracy is required and the needed FWHM cannot be obtained it is possible to synthesize a wider FWHM by summing images of a scan see Section 3 6 2 7 3 6 2 4 Deciding target position and orientation The presence of ghosts and the centre to edge wavelength variation drive target position on the OSIRIS FOV To avoid excessive wavelength variation the target should be as centred as possible but it cannot be placed right In the centre because aside of falling into the gap between detectors a mirrored ghost image of the source will overlap with the real image This might be acceptable in some cases for example if the user is interested in radial dependences only However in general the target should be placed near the optical centre of the TF but fully off it Near the TF centre but on CCD2 the rightmost is a convenient location If the object 1s elongated the wavelength variation can be minimized by turning the GTC rotator to align the major axis of the target perpendicular to the radial direction for the TF optical centre Figure 3 21 However since the target 15 not at the centre of the TF the TF must be tuned to the red of the line so that the target is observed at the wavelength of the line required This can be evaluated using Equations 3 18 or 3 20 For example a target of a diameter of 2 arcminutes should be placed somewhat more than 1 arcminute from t
52. their use and write the appropriate credits in any paper that may result from the use of these filters The main characteristics of these filters are summarized in the following table FWHM PE SA Filter ID nm nm x10 pix pix pix ADUS s pix U500 17 500 15 503 37 1 323 315 7 1003 7 lt 5 U517 17 520 16 520 31 1 304 430 5 991 6 5 U534 17 536 17 538 51 1 379 421 0 1055 2 lt 5 0551 17 552 14 555 01 2 060 255 8 988 1 10 U568 17 569 14 SAN 2 117 289 8 1008 8 10 U585 17 586 15 588 69 2 327 86 2 1021 2 lt 10 0602 17 603 16 605 75 2 277 212 5 1001 2 10 U619 17 619 16 623 14 2 404 202 3 984 8 10 U636 17 636 16 641 37 2 589 116 3 985 8 lt 10 0653 17 653 16 656 01 2 636 151 1 998 6 10 U670 17 668 16 671 86 2 602 183 3 1037 2 lt 10 0687 17 688 17 691 22 2 366 383 2 946 8 10 U704 17 704 18 707 78 2 725 209 3 1027 1 lt 10 0721 17 720 19 723 12 2 972 04 5 960 0 20 U738 17 738 15 741 80 2 413 328 0 1050 3 15 U755 17 754 15 758 12 2 662 237 9 1032 1 15 U772 17 771 16 774 62 2 931 122 0 1026 0 20 U789 17 789 16 791 22 3 089 123 4 994 3 20 0806 17 806 16 809 42 2 941 200 1 932 8 15 U823 17 825 15 829 15 2 058 152 7 888 0 20 U840 17 840 16 843 57 3 104 150 0 992 2 35 U857 17 856 16 859 97 2 895 249 3 1002 1 25 U883 35 880 34 885 33 2 892 285 2 977 5 65 U913 25 910 28 913 64 4 055 60 4 975 4 50 U941 33 941 34 044 04 3 406 165 0 1067 1 70 Page 64 of
53. there is a distinguishable contribution for wavelengths at 480 490 nm whose second order may contribute somewhat at 960 nm 980 nm depending of the source spectral distribution TES mon 10060 1500 Figure 6 6 Example spectrum of the flux standard star PG1545 035 taken with a 2 5 arcsec slit and 300 secs exposure time The low resolution spectrum with the R300R grism shows the first order of dispersion well centered on the CCD Also visible is the zeroth order on the left and the second order spectrum on the right hand side of the graph The effect is present in all the red grisms VPHs but it s more noticeable at lower resolutions 6 8 Spectrophotometric standards The complete list of spectrophotometric standard stars for flux calibration can be found in Section 14 Page 85 of 148 USER MANUAL 0 Date January 1 2014 6 9 Spectroscopic photon detection efficiency The overall photon detection efficiency in spectroscopic mode was using spectra from spectrophotometric standards stars on photometric nights through a wide slit The results are displayed in the following two graphs This first plot shows the end to end overall percentage detection efficiency in spectroscopic mode individual plots for each grism VPH can be found in Section 11 and the second one shows the limiting magnitudes AB for obtaining S N 5 in 1 h of integration time with OSIRIS 9 GTC OSIRIS spectroscopy mode 0 3 R2500U R2
54. these positions of all the targets in a text file alternatively you can use a spreadsheet tool such as EXCEL and save the file in CSV format containing the following columns img to indicate pre imaging mode Centroid x coordinate Centroid y coordinate Proper motion in RA in arcsec year no effect in pre imaging mode 1 2 3 4 5 Proper motion In DEC in arcsec year no effect In pre imaging mode 6 Slit type for rectangular and C for circular holes 7 Angle of the slitlet in degrees 8 N for normal slitlets and F for a fiducial alignment target 9 Priority indication integer value 10 A target name or any other relevant information Make sure that you have at least 3 fiducials targets 5 or 6 would be optimal that the fiducials are not too bright nor too faint as was described earlier and that they are well distributed over the whole field of OSIRIS as was described earlier in this document ii PMRA XX xxx SlitType C RIV Fiducial Normal F N X TargetName string ced XPIX AAAA XX YPIXIYYYY yy PMDEC AA xxx arcsec year Angle DD a Priority int ced 112 49 396 889 00 00000 00 00000 R 80 000 tgtUnolnCCD ced 873 718 436 525 00 00000 00 00000 R 80 000 0 tatDosInCCD ced 899 417 483 438 0 00000 0 00000 R 90 000 FiduciallNor lgtTresinCCD Figure 7 5 Example of a target input list based on detector pixel coordinates Now you are ready to start using
55. very bright usually saturated sources generate ghosts Figure 3 22 For OSIRIS RTF the integrated flux of the ghost images is less than 1 7 of the integrated flux of the main source Hence for RTF observations unless very bright sources are in the FOV and their ghosts could spoil the 1mage of the target there are no need to worry about it However for OSIRIS BTF as a result of a larger thickness of the internal reflective coating the integrated flux of the ghost image can be up to 15 of the integrated flux of the main source for 610 nm Hence for BTF observations dithering procedure is mandatory to remove these ghosts Figure 3 22 Example of ghosts in a TF The cross marks the optical centre The red circles mark the diametric ghosts of the centre of the galaxy and that of an exponential ghost while the green ones marks the exponential ghosts The second exponential ghost does not produce a noticeable diametric ghost Exponential ghosts cannot be removed by dithering Luckily OSIRIS TF does not have this kind of ghosts Of course ghosts drive the location of the target in the FOV as is dealt in this document in Section 3 6 2 4 As stated above ghosts can be removed using the same dithering method that removes for instance detector cosmetics However dithering move the target in the TF FOV i e it changes the wavelength at which the target is observed This Is specifically severe at the edges of the FOV where the wavelength
56. wavelength AA not equivalent to a constant AZ since the Z relation is in general not exactly linear Figure 3 23 Tunable tomography consists in scanning a wavelength range using the TF For the same telescope pointing a set of images at different wavelengths are taken Please note that further on this document AX is NOT the FSR of Equations 3 5 and 3 7 but the scan step or wavelength step between consecutive exposures in tunable tomography Page 54 of 148 USER MANUAL 0 Date January 1 2014 The step must be carefully chosen since for a given wavelength range to be scanned a step too fine will increase the observing time and overheads required but a step too coarse would introduce larger photometric errors that can be evaluated using Equation 3 25 but now considering that the maximum error will be half the scan step 1 in the worst situation an emission line would be located in the middle of a step AA 1 T i 3 27 on T In this observing mode the different images are not combined but analyzed separately Usually aperture photometry of the sources of each image provide pseudo spectra that are used for identifying emission lines and determining its fluxes and Doppler shifts or redshifts In the case that the TF images are going to be used for continuum subtraction the images of the same scan or several of them added together can be used for this purpose as long as they are separate
57. 0 580 585 590 595 600 605 610 Wavelenath nm Wavelenath nm f599bp22 f608bp22 100 T T T T T T 100 T T T T T T 90 F 4 90 4 80 F 4 80 4 70 4 70 4 Transmission o T 1 96 Transmission T 40 1 40 4 30 4 30 4 20 1 20 1 10 10 sl 0 l 1 l 1 1 1 0 l 1 l 1 l 1 585 590 595 600 605 610 615 620 595 600 605 610 615 620 625 630 Wavelenath nm Wavelenath nm 1617bp23 1627bp24 100 T T T T T T T 100 T T T T T T T 90 4 90 4 80 4 80 4 70 1 70 1 5 5 ig ser 1 60 4 50 9 50r 1 40 1 40 5 5 30 4 80 4 20 1 20 1 10 H 10 0 1 1 1 1 1 0 l 1 1 1 1 1 600 605 610 615 620 625 630 635 640 610 615 620 625 630 635 640 645 650 Wavelenath nm Wavelenath nm Page 125 of 148 USER MANUAL 0 Date January 1 2014 16386 25 16496 25 1661bp27 T T T 655 660 665 Wavelenath nm 645 650 655 Wavelenath nm 635 640 645 Wavelenath nm Figure 10 1 From left to right and top to bottom measured central spectral response of Order Sorter Filters according to increasing wavelength for normal incidence Central wavelength and bandpass are indicated on top of each plot 10 2 Red Tunable Filter FWHM TF irange FWHM TF range Filter ID Filter ID nm nm nm nm nm nm f657 35 657 20 35 0 649 660 f819 52 819 0
58. 0 700 720 740 760 620 640 660 680 700 720 740 760 780 Wavelength nm Wavelength nm Filtro f 38bp4B5 Centro Filtro f 54bp50 Centro 100 100 90 90 80 80 70 70 60 c 50 50 e 40 s 40 30 30 20 20 10 10 0 0 640 660 680 700 720 740 760 730 800 550 700 750 Wavelength nm 800 Wavelength nm Transrnission eO Transmission 96 c2 cen e co e e e e e rsa e e e e e Transmission 96 Transmission 96 No Q9 e e co e ce e e er e e e e e e USER MANUAL V3 0 Filtro f 7 bp50 Centro 100 90 80 70 60 50 40 30 20 10 0 660 680 700 720 740 760 780 800 8 Wavelength nm 28 Filtro 18026 51 Centro 100 90 80 70 60 50 40 30 Transmission gt e e Transmission 96 gt ho oo e co e e e e e e e e e c 750 800 8 Wavelength nm e Filtro fS38bp58 Centro 100 90 80 70 50 40 30 20 Transmission o 5 740 760 780 800 820 840 860 880 90 Wavelength nm e Filtro f878bp59 Centro 100 90 80 70 60 50 40 30 20 10 800 820 840 860 880 900 920 940 Wavelength nm Page 127 of 148 Date January 1 2014 Filtro f785bp48 Centro 580 700 720 740 760 780 800 820 840 Wavelength nm Filtro f819bp52 Centro 720 740 760 780 800 820 840 860 880 Wavelength nm Filtro fS58bp58 Centro 100 30 80 70 60 50 40 Transmission 30 20 10
59. 080 RA 06 51 12 688 Orient 0 not xy scaled Orient 179 1232 a i 41 28 24 45 _ reimaging PM_dec pp elmaging PM units are arcsecs year s Last MSG Project file successfully loaded Figure 7 3 The principal panel of the Mask Designer tool Next we describe each point in somewhat more detail Menu options At the very top of the MD window one finds the usual pull down menu options Here one can save a project load a previously defined project configure the project set default values for slits or open specific windows etc The configuration method is described later when specific examples are presented Slitlet Listing The top left section of the window provides an overview of all the slitlets that have been defined Each slit is given a unique number The target names are copied from the input target list as provided by the user and may be edited through the target information box The listing also indicates the type of slitlet 1 9 R for a rectangular slitlet and C for circular its priority whether its current position is valid and does not conflict with other slitlets and whether the slitlet pertains to a fiducial star By clicking on an entry in this list that entry is highlighted and the information of this slitlet is given in other information boxes and this slitlet 1s highlighted in the graphical mask representations Action buttons There are five action
60. 148 USER MANUAL 0 Date January 1 2014 As in the rest of filters used In OSIRIS the SHARDS filters are placed in the collimated beam and close to the pupil of the instrument at an angle of 10 5 with respect to the optical axis of the instrument This causes that the central wavelength depend on the position in the field with a center of symmetry corresponding to the center of rotation of the instrument located on CCD1 towards the left side of the field This effect small for the standard Broad Band Sloan filters but has a stronger impact in the operation of the SHARDS filters as the filter widths are notably narrower than in the case of Sloan filters Hence this 15 not a defect of the filters but due to the design of the OSIRIS instrument that becomes more prominent as filter pass band gets narrower The central wavelength variation effect is more relevant in the case of medium band filters such as SHARDS and also for the order sorter filters given that the central wavelength shift from edge to edge of the OSIRIS FOV 15 of the same order of the width of the filter Note that the typical shift 14 15 nm would be 1096 2046 for broad band filters Summarizing potentially users of the SHARDS filters set have to take two main aspects into account when using these filters e Thecentral wavelength in the rotation center of the instrument approximately pixel 462 5 995 in CCD1 is different from the central wavelength at the standard po
61. 1s highlighted in the list of slits Slitlet geometry visualization The abovementioned action buttons allow visualization of the geometry of the slitlets The visualisation of different aspects of the geometry of the slitlets can be activated or de activated using a set of tick boxes labeled Geoms Activation spectra shows the projection of the spectra pertaining to the slitlets wcSlit shows possible errors that might occur in the production process of the slitlet according to the manufacturing tollerances of the cutting machine It allows the user Page 95 of 148 USER MANUAL 0 Date January 1 2014 to assess whether 15 risk of contamination by nearby targets slitlnTime this options show the geometry of the slitlet taking into account the proper motion and atmospheric refraction This geometry is the basis for the fabrication definition of the slitlet manufSlit shtlets at the level of the manufacturing machine are defined as sets of rectangles However the various transformations imply that switching between coordinate systems the rectangles will become distorted This options allows the user to see the effects of such distortions and what shape will be sent to the manufacturing machine minSeparationSlit not activated by default shows the manufacturing safety margin around the slits shufflingSpectra not activated by default in case of shuffling spectra over the detector spe
62. 3 52 4 803 818 f666 36 666 84 35 5 660 670 838 58 838 57 57 8 818 845 f680 43 680 21 43 2 670 685 f858 58 858 21 57 9 845 860 f694 44 694 38 44 0 685 695 878 59 878 23 59 3 860 885 f708 45 708 84 44 9 695 710 893 50 893 21 49 6 885 900 725 45 25 29 a2 710 725 902 44 902 40 40 1 900 910 738 49 737 98 46 1 725 735 910 40 910 64 40 5 910 912 f754 50 754 25 49 6 735 755 f919 41 918 95 40 8 912 920 f770 50 770 57 49 7 755 770 f923 34 923 85 34 2 920 925 f785 48 785 58 47 6 770 788 9027 34 927 94 34 4 925 930 802 51 802 02 51 3 788 803 932 34 932 05 34 5 930 935 Transmission 95 Transmission 95 Transmission 96 USER MANUAL V3 0 Filtro 657bp35 Centro Page 126 of 148 Date January 1 2014 Filtro 66bp36 Centro 100 100 90 90 80 80 70 70 gp 5 50 5 50 o o S 40 40 30 30 20 20 10 10 D D 610 620 630 640 650 660 670 680 690 700 560 580 600 620 640 660 680 700 720 Wavelength nm Wavelength nm Filtro f680bp43 Centro Filtro 694bp44 Centro 100 100 90 90 80 80 70 70 60 x 60 c 50 50 e 40 s 40 30 30 20 20 10 10 580 600 620 640 660 680 700 720 740 580 600 620 640 550 660 700 720 740 760 Wavelength Wavelength Filtro f709bp45 Cent i6 Filtro 723bp45 Centro 100 90 90 80 80 70 70 60 amp S 50 50 40 s 40 30 30 20 20 10 10 600 620 640 660 68
63. 5 5 0 1 L 1 l 1 1 1 l 475 480 485 490 495 500 505 480 485 490 495 500 505 510 Wavelenath nm Wavelenath nm fA99bp15 f504bp16 100 T T T T T 100 T T T T T 4 90 4 80 EI i 70 is 5 5 4 a a E 5 c 7 2 50r 9 9 4 40 sok 5 5 4 30 ul 4 20 J 2 10 E zl 1 1 0 1 1 l 1 485 490 495 500 505 510 515 490 495 500 505 510 515 520 Wavelenath nm Wavelenath nm 5095 16 f514bp16 100 T T T T T 100 T T T T T 90 4 90 80 4 80 4 70 4 70 4 5 5 ig Ser 1 a 60 4 a a E 9 50r 4 9 50r 4 9 9 40 40 4 a 5 30 30 4 20 4 20 4 10 4 10 F 4 0 1 1 l 1 0 L 1 l 1 495 500 505 510 515 520 525 500 505 510 515 520 525 530 Wavelenath nm Wavelenath nm Page 123 of 148 USER MANUAL 0 Date January 1 2014 519616 f525bp17 100 T T T T T 100 T T T T T 90 4 90 F 4 80 80 4 70 r 60 F 60 F Transmission o 1 96 Transmission T 40 4 40 30 4 30 20 4 20 10 10 0 1 1 l 1 0 1 1 l 1 510 515 520 525 530 535 540 510 515 520 525 530 535 540 Wavelenath nm Wavelenath nm f530bp17 f536bp17 100 T T T T T 100 T T T T T 90 4 90 80 4 80 70 4 70 4 60 F Transmission o T 1 96 Transmission o T 40 4 40 4 30 4 30 4 20 4 20 4 10 4 10 4 0 1 1 1 l 1 0 1 1 1 l L 520 525 530 535 540
64. 5 Tuning speed The tuning can be changed in an interval between 10 to 100 ms depending on the change in Z For large Z differences the TF control system automatically moves the etalon in steps to avoid out of range failures For fast modes it is advisable limiting the range of Z movement to the minimum hundreds 3 6 Observing with OSIRIS Tunable Filter 3 6 1 Tunable Filter vs Spectroscopy For a complex instrument such as OSIRIS with a wide variety of observing modes and sub modes one of the concerns of the user is whether the chosen mode is the most appropriate for the observing program Since tunable filter imaging is a relatively new and not widespread mode most confusions arise between the convenience of the use of this mode versus spectroscopy In brief the main advantages of TF versus spectroscopy is the ability to flux calibrate the emission a tricky issue in MOS and even in long slit spectroscopy slit slicing the image differential refraction centring errors and of obtaining 2D emission line maps for targets over the FOV either extended or of small size The main disadvantage is that only one wavelength can be observed at a time The following table and the flux diagram below help deciding the most appropriate mode elocity fields amp line profiles at high R Approximate redshift should be known Redshift knowledge not required osition not required survey osition required pre imaging This introduce bia
65. 5 s However this time can be reduced by defining a single readout window limiting the extent of the readout area along the slit Also the higher readout of 500 kHz can be used to reduce the readout time to 12 s and even less Page 69 of 148 USER MANUAL 0 Date January 1 2014 with windowing However this readout speed is a non standard operation mode in OSIRIS and 1ts performance 15 not guaranteed As the fast photometry mask 15 restricted to 3 size in the vertical direction good seeing conditions are required for its use It is also possible to use the longslit masks as fast photometry masks allowing up to 10 of vertical aperture However in this case only half of the detector will be completed before readout since the position of the long slit 15 centered in the FOV Due to the high flexiblilty and the multiple possible combinations in using this observing mode fast photometry with OSIRIS 15 only offered in visitor mode Prior to defining your observing proposal it 15 strongly recommended to contact GTC staff astronomers to evaluate the optimum mode of operation 5 2 Frame Transfer Frame transfer capability in OSIRIS uses a half field mask see Figure 5 2 with an accessible FOV of 7 x 3 5 approximately In this operation mode only half of the detector is exposed while the other half of the detector 15 being read out The minimum exposure time allowed is now imposed by the time required to displace the charge
66. 5000 6000 7000 8000 9000 10000 Wavelength angstroms Page 144 of 148 USER MANUAL V3 0 Date January 1 2014 13 OSIRIS SLOAN PHOTOMETRIC STANDARDS Photometric calibration for OSIRIS Broad Band imaging is done via a Sloan standard set taken from Smith el al 2002 AJ 123 2121 Name DEC J 7 120060 Page 145 of 148 USER MANUAL 0 Date January 1 2014 Page 146 of 148 USER MANUAL 0 Date January 1 2014 14 OSIRISSPECTROPHOTOMETRIC STANDARDS Flux calibration for OSIRIS Long Slit Spectroscopy OSIRIS MOS and OSIRIS TF imaging is done via the following subset of standards taken from the ING spectrophotometric standards list Name G158 100 GD50 HZ15 G191 B2B GD71 Hilt600 0823 546 Feige 34 GD 140 HZ 21 RA DEC J2000 00 33 54 5 12 07 58 03 48 50 06 00 58 30 4 04 40 39 32 08 40 45 3 05 05 30 6 52 49 56 05 52 2731 15 53 16 6 06 45 13 33 02 08 14 1 06 47 37 99 37 30 57 0 08 26 49 4 54 28 01 10 39 36 7 43 06 10 11 37 05 1 29 47 58 12 13 56 6 32 56 30 12 57 02 3 22 01 56 0 5556 14 8 14 06 12 6 14 5 10 4 12 1 14 4 12 4 14 7 13 3 Wavelength coverage 320 1000 nm 320 920 nm 320 840 nm 320 1000 nm 320 1000 nm 320 1000 nm 320 940 nm 320 800 nm 320 900 nm 320 1000 nm 320 900 nm 320 1000 nm Reference Oke 1990 AJ 99 1621 Filippenko amp Gree
67. 500V R2500R R2500 0 25 R1000B 0 2 gt O D o TT 0 1 0 05 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A OSIRIS limiting magnitudes spectroscopy mode 24 5 R2500U R2500V R2500R R2500 24 prts R2000B te un R 5 0 0 gt K R500R sere 8 23 5 R300B g 2 dm 3 II en x Ta 225 E 22 21 5 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelength A Figure 6 9 Overall photon detection efficiency of GTC and OSIRIS in spectroscopic mode above and limiting magnitudes S N 5 in 3600s exposure time achieved in OSIRIS spectroscopic mode assuming dark conditions seeing 1 0 arcsec and airmass 1 2 below Page 86 of 148 USER MANUAL 0 Date January 1 2014 7 MULTI OBJECT SPECTROSCOPY 7 1 General description OSIRIS possesses significant spectroscopic multiplexing capability through the use of focal plane multi slit masks instead of a single long slit Hence observing in MOS mode requires the design and construction of a physical mask that contains a number of small slits or slitlets where each slitlet produces the spectrum of a source in the field By placing a mask with carefully designed and manufactured slits in the focal plane spectra of several including tens of objects can be observed at the same time
68. 57 MasterFlat05666 Lines 2048 2 05952 Lines 2048 SkuFlat SkuFlat MasterFlat05709 Lines 2057 SkuFlat 709 45 200 9 1000 2000 3000 4000 Column pixels Figure 3 28 Horizontal cut for three Sky Flat images taken with OS666 left OS709 center 05932 right The intensity gradient observed is due to the combination of a different contribution of the Sky lines and a different sensitivity of the CCDs from redder to bluer wavelengths For calibrating the data obtained with the OS filters when used in imaging mode the spectrophotometric standards for both tunable filter imaging and long slit spectroscopy observations can be used see Table in Section 13 The spectral responses of each of the OS filters are available at http www gtc iac es instruments osiris osiris php Tunable_Filters The graph below shows the overall photon detection efficiency of OSIRIS TF Order Sorters at GTC including the contribution both of the telescope and instrument optics system OSIRIS TF Order Sorter filters 0 45 OS RTF OS iii 0 4 0 35 gt 0 3 tu 0 25 0 2 0 15 0 1 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A Figure 3 29 Overall photon detection efficiency of GTC and OSIRIS with the TF Order Sorter Filters Page 62 of 148 USER MANUAL 0 Date January 1 2014 The OS high inclination also makes impossible to use two contiguous OS to produc
69. 8 USER MANUAL 0 Date January 1 2014 For better accuracy Ar n lt r 2A2 3 22 where n is the number of nm of the allowed drift and AX is the wavelength variation in nm from the centre of the TF to the ring Eq 3 18 and 3 20 AA 5 04A r forRTF 3 23 3 84 r for BTF 3 24 with the radius r In arcminutes If the ring radius varies in more than the tolerated value the Z must be changed If r increases the Z must decrease and vice versa This The above expressions can be used for and external check of fast recalibration without using the calibration lamps However it is advisable to use the calibration lamps to avoid errors from a tired and sleepy user For a good sky line map the reader is referred to Hanuschik 2003 that can be found on line at http www eso org observing dfo quality U V ES pipeline sky spectrum html Figure 3 16 Sky ring at 894 35 nm with the OS 878 59 with FWHM 1 21 nm tuning the TF at 898 2nm for obtaining a ring radius of 1100 pixels The exposure time is of 120 s Page 45 of 148 USER MANUAL 0 Date January 1 2014 3 5 4 Tuning accuracy The theoretical tuning accuracy is 0 02 nm in wavelength and FWHM as provided by the CS 100 etalon controller in most cases this is the typical value of 1 bit in Z The real accuracy in practical terms is driven by the wavelength calibration accuracy that can be of the order of 0 1 0 2 nm 3 5
70. 88 7 299 06 B 8666076 7500 7000 6500 Wavelength angstroms 6000 5500 HgAr Ne Xe calibration lamps OSIRIS 25001 lex 6L c66 lex 076676 HV 9877696 lex 690916 Mv 796 6CL6 lex er lex ZSC 6568 IPN Z98 688 __ gt que vum o q 877698 66671668 0969658 V CEP LOSS HV Zv9 VCV8 7092 68 19X 0170828 lax 9128 wieeiia HY 607918 HV LIE SLL8 HV S82 rL08 LY 9619008 HV 92 8v67 HV 2087644 HV 90160697 ION rhZ GEG7 IPN L28 88V7 Mv 86 8 7 7438 898 Nel 9000 9500 10000 Wavelength angstroms 8500 8000 7900 Page 82 of 148 USER MANUAL 0 Date January 1 2014 6 5 1 Arc line ghosts All the OSIRIS grisms show some minor ghost effects in the arc line Images Those ghosts are due to internal reflections within the grisms and can be identified as the curvature in these spectra differs from those of the main arc lines The intensity of these ghosts 1s negligible and they do not affect the line identification or the science images Ui R300R Ne R1000B HgAr R1000R HgAr Figure 6 4 OSIRIS grisms ghost effects shown in the arc images 6 5 2 Spectral solutions The following table shows the example solutions obtained with the IRAF routine IDENTIFY correspondin
71. GRANTECAN S A Version 3 0 OSIRIS USER MANUAL January 1 2014 OSIRIS USER MANUAL Antonio Cabrera Lavers OSIRIS Instrument Specialist This document is based on a first version of the manual from J Instrument P I and the OSIRIS Instrument Team under the direction of the Instituto de Astrof sica de Canarias Page 2 of 148 USER MANUAL 0 Date January 1 2014 TABLE OF CONTENTS LISLOPFADBREVENDPIONS 2 a u Q Da uns nu us 5 1 INSTRUMENT CHARACTERISTICS 6 1 1 ON ERVIE Wy mua 6 I2 OSIRIS focal plane Masks alpa ODSEVNE 9 Id 10 TID Vignewine ss 11 LIO Jueldorieutaton n Qa una aaa Q sasa 11 TET 50107 102 12 1 1 8 Environmental conditions 12 1 2 DETECTOR Su ua unu decipi sciL uu SL DI OD usce LIE E D 12 LLLI JSSCHIDHIVONH 12 1 2 2 OSIRIS standard CCD operation modes 14 1 2 5 OSIRIS CCDs linearity
72. IRIS operation from semester 2014A onwards the standard readout mode will be 200 kHz in all the observing modes provided by the instrument The initial purpose of allowing two different readout speeds was to provide a low readout noise mode for spectroscopic observations different than the one used for imaging modes However the reasonable good performance of OSIRIS CCDs allows to get low readout noise levels either at 100 kHz or 200 kHz hence the only real difference when using those modes is having different readout times 123 OSIRIS CCDs linearity dark current level cross talk In the OSIRIS standard operation mode detector linearity is guaranteed up to the full 16 bits signal maximum Figure 1 5 During the first months of operation of the instrument OSIRIS suffered of a very high dark current resulting from an excessive temperature of the CCD that was not correctly reported Those values are for CCD1 Gain for CCD2 is about 596 lower that these lt ADUs gt USER MANUAL 0 Page 15 of 148 Date January 1 2014 60000 50000 40000 30000 20000 10000 v by the CCD thermometry system A redesign of the thermal coupling between the liquid Nitrogen container and the CCD has resulted in a notable improvement of the dark current which is now at acceptable levels of about 10 12 ADUs h for a 2 x 2 binned pixel Hence since February 2010 no dark images are needed for OSIRIS data analysis A slight cro
73. MANUAL 0 Date January 1 2014 lransmission of a Fabry Perot filter 1 0 d 3um 0 0 finesse 0 8 i Bel see 0 6 0 4 Transmission coefficient 0 0 E 580 600 620 640 660 680 700 Wavelength nm Figure 3 2 Variation of the transmission profile of FPF with finesse The profiles were determined for an ideal FPF Equation 2 25 with R 0 68 0 81 and 0 92 A 0 Orders m 10 and m 9 are shown front elevation side elevation capacitor A reflective coating reference capacitor B optical gap o piezo electric transducer Figure 3 3 Front elevation and side elevation of a Queensgate Instruments etalon Note that the thickness of the optical gap is exaggerated Page 28 of 148 USER MANUAL 0 Date January 1 2014 In Figure 3 3 we show the structure of a gap scanning etalon manufactured by Queensgate Instruments Ltd now IC Optical Systems In recent years these etalons have undergone considerable improvements It is now possible to move the plates between any two discrete spacings at very high frequencies 200 Hz or better with no hysteresis effects while maintaining 2000 parallelism measured at 633 nm The etalon spacing is maintained by three piezoelectric transducers 3 1 2 Charge shuffling Central to almost all modes of OSIRIS use is charge shuffling Charge shuffling is movement of charge along the CCD between multiple exposures of the same frame befo
74. MS are quite narrow and nearly Gaussian from peak to half transmission Then the line width must be quite narrower than the TF FWHM or otherwise some flux will be lost It can be easily demonstrated that assuming Gaussian line profiles the flux error can be approximated by I a Flux error 96 3 26 21 02 oA where is the TF FWHM and is the line width For example observing a line with the same width than the TF result in loosing 28 of the flux a more precise calculation gives 36 Line uu ON band Relative response 0 6540 6550 6560 6570 6580 6590 6600 6610 6620 6630 6640 Wavelength Figure 3 20 Comparison of and line profiles The following table can be used for selecting to most suttable FWHM according to the expected line width Please note that they are approximate values Page 50 of 148 Date January 1 2014 USER MANUAL V3 0 Flux error Table 3 1 Approximate error fluxes depending on line width and TF FWHM A For example the typical velocity field of a spiral galaxy 250 km s at zero redshift would require TF FWHM of at least Inm at Ho for an error smaller than 5 and the minimum FWHM recommended for the red TF at is of 1 2 nm Hence this 15 not a problem in this case but it might be for OII 372 7nm blue TF or when observing objects at significant redshifts where the line widths are expanded by the factor 1 z Since
75. MV G9 018 V ZS 798 zd A e 2 lt 992108 7Y 15 9008 98ZTL08 MV 2619008 3 v o s 9118162 5 5 gt 91 86 c c Ee y ZS9 PLSZ 1 698 06 Z 86 8 IJV 9662424 m 2 12 8LZ 904 e S969 C N x gt x lt 5 D O 2 4 8k Ss z lt DH 99 062S oz DH 99 064S gt I e Y DH 9656975 Ca IDH 969 695 N S S IBH S Z 09vS a Z gt x e O o e x a 5 S 9 24 Y un 9z 8s v 9ze 8sev O e x IBH IBH 9 7 5 51 09598 N snav Aie1iqiv snav Wavelength angstroms Page 133 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R300B Ne calibration lamp I N0SS LCC6 I9N 657 1026 I9N 229 8T L6 I9N 85 C808 ION L81 164 IPN PZZSESZ IHON L28 88v7 I9N 668 8 vZ I9N 49 1 Sv CZ I9N 8 6 5114 I9N 2976269 ION t0 2129 9278 99 ION ZZ8 Z S9 ION 8699099 I9N 96 8659 I9N 8vC COPS ION 8Zt EEO IPN Y69 919 ION 90 v L 9 9 56 992 ION 91 9609 I9N 86 7209 I NT S S26S ION bes byes 9 9681985
76. PH R2500I shows a notable displacement larger than 1 arcsec while in the rest of VPHs this effect is negligible some grisms are also shown for comparison Please note this when observing extended objects or crowded regions with this VPH to avoid confusion between different spectra Grism VPH AX pix Grism VPH AX pix R300R R2500U R1000B 0 5 R2500V 1 5 Page 75 of 148 USER MANUAL 0 Date January 1 2014 65 Arcline maps Instrument Calibration Module ICM at GTC has three different calibration lamps HgAr Ne and Xe In this subsection the arc lines for the OSIRIS grisms VPH are shown together with the exposure times used for produce these for reference The following table summarises the optimal exposure times for each lamp when powering on two lamps for each type using the standard spectroscopic configuration 200 kHz readout speed binning 2 x 2 RS0B 52s 36s RI00B 60s 35s R280U 200s 12008 R2500R GR 420 25s For some of the OSIRIS R2000 2500 VPHs long exposed lamp images are required to obtain enough signal which allows a good line identification For this reason a master arc collection with the arc lamps images obtained with OSIRIS R2000 2500 VPHs with the 0 6 slit can be retrieved from http www gtc iac es instruments osiris osiris php Longslit Spectroscopy Note that this master arc collection was obtained using a 0 6 slit If
77. S 8 1 Exposure time calculator ETC For preparing observations estimating exposure times for the different modes the OSIRIS ETC can be found in http www gtc iac es instruments osiris php Also for Tunable Filter observations it is highly recommended to use the TF Setup Tool also available at http www gtc iac es instruments osiris php before using the ETC The TF Setup Tool allows to perform very useful estimates for the TF operation as obtaining the available widths for our wavelength of interest as well as to define the corresponding Order Sorter Filter that has to be used for the observation calculating the change in wavelength along the OSIRIS FOV estimating the effect of the sky lines in our tuned filter Estimates from the ETC are obtained by using the most recent data coming from the instrument and are well in agreement with the obtained results in the scientific operation of the telescope In any case there are also some useful information to take into account when using the OSIRIS ETC If you were awarded with Spectroscopic night conditions it s advisable to add 0 5 mag to the target magnitude when obtaining S N estimates as it was observed by daily monitorizing of OSIRIS zeropoints see Section 2 1 1 1 When using the R2500I VPH increase the exposure times a factor 1 2 to obtain the S N given by the ETC This VPH suffers some internal fringing effects that slightly decrease the S N in the scie
78. SER MANUAL 0 Date January 1 2014 Ambient dew point Degrees Ambient dew point in Celsius in Celsius degrees Celsius degrees EKWI 3 pe we Integer Filter Wheel 1 currentPosition currentPosition EKW2 5 x Integer Filter Wheel 2 currentPosition currentPosition EKW3 5 Pies we Integer Filter Wheel 3 currentPosition currentPosition EKW4 7 D 7 Integer Grism Wheel currentPosition currentPosition 5 2 P Integer Mask positioner currentPosition currentPosition Red TF EKW6 37634 Displacement in Z Encoder units x DisplacementZ encoder units EKW7 69 RU vat Encoder unites Tunable filter Red currentOffset encoder units EKWI2 34680 uM Encoder units Tunable filter Red position X encoder units EKW13 24680 RM M Encoder units Tunable filter Red position Y encoder units Red TF auto T EKW16 34680 adjustement X Encoder units Tunable nier Red poson ruto I Adjustment X encoder units Red TF auto l EKW17 32080 adjustement Y Encoder units unable Ree poston nuts Adjustment Y encoder units Red TF auto M EKWIS 34350 adjustement Z Encoder units Tunable Hier Ree POSON AO Adjustment Z encoder units ELAPSED 45 810 Total elapsed time Time difference between End and from start to end s start of observation Total elapsed time Time difference between ELAPSHUT 6 966 seconds followed Seconds CLOSETIME OPENTIME in by ms seconds Page 109 of 148
79. XIS2 NSHIFTS NUM IMAG 0 00024826789740 7 7156859333E 05 0 90281625366211 3 28916454315186 0 71310837604523 NOMASK 55971 6491228745 true ONLYDOWN 1049 2051 20 1 Radians mirror RX position GTC secondary m Radians mirror R Y position GTC secondary mirror UX position GTC secondary mirror UY position GTC secondary mirror UZ position Mask name N A Modified Julian day D at observation start aum Mosaic active or N A not Direction of charge desplacement m Number of channels Integer of data Number Integer axis length of data axis 1 Pixels length of data axis 2 Pixels Number of lines charges are moved Integer on the CCD Total number of images into the Integer sequence Date January 1 2014 GTC secondary mirror RX position GTC secondary mirror RY position GTC secondary mirror UX position GTC secondary mirror UY position GTC secondary mirror UZ position Multi object spectroscopy mask name Modified Julian day at observation start Whether CCD mosaic is active or not Direction of charge desplacement can be a eONLYDOWNAE ONLYUP ALT_START_UP ALT_START_DOWN Number of amplifier used during CCD readout Number of data axis zero on primary fits header extention Number of data pixel in axis 1 Number of data pixel in axis 2 Number of lines charges are moved on the CCD in cha
80. are continuous and geometrically correct Also this step 15 described in detail in the following section When using a pre image for the mask design the OSIRIS image should be taken with the correct orientation and elevation so that de design based on this image will reflect the reality at the moment of observing with the mask Before designing a mask the user should consider the right orientation of the field in order to take into account the optimal angle of the slits projected onto the sky This is important to reduce the effects of differential atmospheric refraction that may introduce important slit losses This problem is exacerbated by the fact that currently the dome shutter cannot be fully opened and hence objects passing through the dome blind spot cannot be observed in their optimal position Moreover although a mask design may be optimized for a certain hour angle of observation there is no guarantee that the observation can be scheduled at exactly that hour angle Here follow some simple guidelines that will probably work well for most cases For fields that are to be observed close to the meridian without being affected by the dome shutter limitation vignetting for elevations above 72 degrees the slits are best oriented in the North South direction However fields that pass close to the zenith and will be affected by the dome shutter 1 9 declinations between approximately 10 and 47 degrees the slit orientation is best placed E
81. ast West so that the field can be observed with the same mask both when the field is rising and when it is setting since the slits will remain reasonably close to the parallactic angle while when crossing the meridian atmospheric refraction is at its minimum and deviations from the parallactic angle will have little impact Although other angles are in principle possible for the time being only slit orientations N S or E W will be accepted A simple calculator for atmospheric refraction and parallactic angles is available at http gtc phase2 gtc 1ac es science astroweb atmosRefraction php For a more detailed description of the issue of the choice of slit angle we refer to a paper by Szokoly 2005 A amp A 443 703 And a detailed study on atmospheric refraction and its effects on spectroscopy can be found in Filippenko 1982 PASP 94 715 7 6 The Mask Designer tool Here follows a practical description of how the OSIRIS Mask Designer tool is used In what follows we refer to MaskDesigner MD Version 3 25 released November 2013 The MD was developed by Txinto Vaz Cedillo based on previous work by J L Gonz lez Serrano and Page 91 of 148 USER MANUAL 0 Date January 1 2014 co workers 2004 Experimental Astronomy 18 65 with important input and invaluable assistance from Angel Bongiovanni 7 6 1 Starting up The MD software is written in JAVA and uses elements of the JSky project see http archive eso org cms
82. ates X Y 250 994 of the CCD2 binned pixels This position minimize the amount of cosmetic effects of the CCD2 compared to those on the CCD1 On this area the distortion of the spectra is very low and sufficiently far from the central gap in order to allow a good sky subtraction To ensure accurate centering on the slit an acquisition image and a through slit images are normally taken During the observation after the acquisition Image is obtained with the target placed at the pixel 250 994 in CCD2 an iterative process for slit alignment is employed until the object is well centered This 1s verified by taking through slit images For this reason the coordinates for the target in the acquisition and through slit images can be slightly different Due to the obscuration present in one of the edges of OSIRIS FOV and the manufacture process in producing the slits the maximum distance allowed for placing two targets in the same slit configuration is 7 4 arcmin For a proper sky subtraction however no distances larger than 7 0 arcmin are recommended in order to get enough pixels for the background estimation on both sides of the targets Likewise if offseting is required during the observation the maximum distance to the targets has to be estimated accordingly for example a maximum distance of 6 5 6 7 arcmin between the targets 1 a good approximation for this kind of observations Page 73 of 148 USER MANUAL 0 Date Januar
83. beam towards the filter wheels and the camera optics Both the collimator and folder are covered with a silver protected coating of high red and blue reflectivity Figure 1 2 Reflection 9 o s Colimator 86 Measured reflectivity Folder Reflection at 45 0 Measured reflectivity 400 500 600 700 800 900 1000 Wavelength nm Figure 1 2 Collimator and folder flat measured reflectivity curve with respect to the requirements straight stepper lines Page 8 of 148 USER MANUAL 0 Date January 1 2014 Filters grisms and Tunable Filters TFs can be inserted in the collimated beam near the pupil via four filters wheels three for standard filters and the fourth at the pupil for TFs and grisms Each filter wheel has 9 positions and the grism wheel holds apart from the tunable filters up to 6 dispersive element Together they allow selecting the adequate combination of these elements for using the different observing modes described in the following subsection Conventional filters are used for imaging and for order sorting the TFs and grisms The filters insert into the beam at an angle of 10 5 degrees in order to avoid ghost images The all refractive OSIRIS camera consists of 9 spherical lenses The last lens is the dewar window The camera effective focal length of 181 mm provides the required detector scale 0 127 arcsec pixel on a flat focal plane that is tilted 1 83
84. cat radecxy cat toleranc 5 ptoleranc 40 Xin XXXX X yin yyyy y xmag 0 254 ymag 0 254 xrotation 180 yrotation 0 projection tan lngref aaa aaaaaa latref dd dddddd lngcolumn 2 latcolumn 3 xcolumn 2 ycolumn 3 Ingunits degrees latunits degrees matchin triangles nmatch 40 Some cautions should be taken before running ccxymatch 1 it is necessary that a position on the detector given by parameters xin yin corresponds to a previously known sky position given by parameters 1nref latref ideally this position should be close to the image centre 1 xrotation and yrotation correspond to a image orientation with north up and east left 11 depending on the method used for generating input files the parameters 1ngcolumn latcolumn xcolumn and ycolumn could change and iv nmatch must be smaller than the number of lines in xy cat Possible redundancies in the output file will be naturally discarded in the following step Use the command help ccxymatch at the TRAF prompt to obtain more information 9 2 2 Astrometric Solution To find the astrometric solution for each frame the IRAF imcoords ccmap task should be used Figure 9 1 below represents the mean distortion vectors in the sense of deviation of positions from linear solution respect to the general full precision astrometric solution in Page 117 of 148 USER MANUAL 0 Date January 1 2014 pixels 5 times magnified for each OSIRIS detector and without filter F
85. ch individual image MasterFlats are available separately for each CCD of OSIRIS as they have a slightly different gain and bias level The latest master flats are available from the GTC web pages 2 4 Sloan Photometric Standards Photometric calibration for OSIRIS Broad Band imaging is done via a Sloan standard set taken from Smith el al 2002 AJ 123 2121 The complete list of standards can be found in Section 12 Page 23 of 148 USER MANUAL 0 Date January 1 2014 3 TUNABLE FILTER IMAGING 31 OSIRIS Tunable Filters description A key aspect of OSIRIS is the use of tunable filters TFs OSIRIS TFs are a pair of tunable narrowband interference filters FabryPerot etalons covering 450 671 nm blue arm and 651 935 nm red arm They offer monochromatic imaging with an adjustable passband of between 0 45 and 2 nm In addition TF frequency switching can be synchronized with movement of charge charge shuffling or frame transfer on the OSIRIS CCDs techniques that have important applications to many astrophysical problems 3 1 1 Introduction to FabryPerot filters FPFs In its simplest form a FabryPerot filter FPF consists of two plane parallel transparent plates which are coated with films of high reflectivity and low absorption The coated surfaces are separated by a small distance typically to mm to form a cavity which is resonant at specific wavelengths Light entering the cavity undergoes multip
86. close the window after having edited your default values Now it s time lo load the list of coordinates by selecting File Import targets and selecting the file you prepared If the software has accepted your file you should see your list of slitlets appear in the table in the MaskDesigner window The list will show which slitlets refer to fiducial objects or normal targets and whether the MD software encounters any problems with the design see the column labeled valid The slitlets that are not considered valid will require further attention Typical problems that are encountered are overlapping spectra with other slitlets that the slitlet falls outside the mask or that the spectral range falls outside the detector The design can be tuned in order to reduce the conflicts as will be shown in the next points If you click on an entry in the list then the numbers in the other panels will display the details refering to the selected slitlet The Sky Editor is the most suitable visualisation tool to verify the mask design as it projects the slitlets in the same equatorial coordinate frame as was used to define your targets Slits and the spectral projection might look curved and distorted which is due to the projection of rectangular outlines on the equatorial coordinate grid The Sky Editor allows you to load images and catalogues For instance to overlay an image of the Digital Sky Survey in the Sky Editor panel go to Catalog Image Serv
87. cted variations of the wavelength dependence across the FOV that depended non linearly on etalon gap and wavelength and that they attributed to variations of the focal distance of the camera although clearly this cannot be the origin of this effect 3 2 1 Red Tunable Filter For calibrating the wavelength dependence across the FOV for the OSIRIS red TF Images of different emission lines at different wavelengths covering the full OSIRIS wavelength range were obtained For each emission line the red TF was tuned at different wavelengths The results were checked against OSIRIS TF data of cluster galaxies covering the whole OSIRIS FOV with spectroscopy available from the literature From these data the following wavelength dependence across the OSIRIS FOV 15 derived 4 5 04 r 3 18 where is the central wavelength tuned r is the distance in arcminutes to the optical centre of the TF Within the inner 2 arcmin this expression 15 very accurate for any wavelength Figure 3 7 Even at the edge of the 4 arcmin radius OSIRIS TF FOV the maximum error is of the order of the tuning accuracy 1 2A for most wavelengths and always within 6A in the worse Page 33 of 148 USER MANUAL 0 Date January 1 2014 cases Figure 3 7 This accuracy is enough for most applications given the TF tuning accuracy already mentioned and that if images are dithered an additional wavelength shift depending on the
88. ctra are displaced over the detector by a certain number of lines before taking another exposure This option will show where the spectra will fall in order to avoid overlapping the displaced spectra with the actual slitlet spectra Slitlet details Below the action buttons one finds a box that displays the details of the selected slitlet in three different coordinate systems the equatorial sky coordinates the physical mask coordinates and the pixel detector coordinates For each set of coordinates its position 15 shown the orientation as well as the range it spans One can toggle between the two by selecting either position or bounds The position of each slitlet can be edited here in order to make small adjustments but this should not normally be necessary Slit properties In the upper right hand corner of the MD window one finds further details of the slitlet Apart from the RA and DEC coordinates one can select or de select fiducial objects and set the wavelength range that is relevant to this specific slitlet Setting this overrides the default values that have been defined in the configuration panel but only within the physical possibilities of the grisms Target details In this last box at the bottom right hand corner of the window one can edit details of the target that Is associated with the slitlet For instance proper motion details can be entered here Mask editor and visualization windows Three
89. d enough to achieve the required photometric accuracy based on TF FWHM scan step and the number of images This might require obtaining some additional images at the end and or the beginning of the scan at the end and beginning would allow averaging possible continuum variations Examples of applications of this method are e Scanning a spectral region for de blending neighbouring lines e Scanning a target looking for systems of high velocity faint or diffuse ionized gas e Scanning blank fields searching for serendipitous emission line targets in a certain volume of universe determined by the FOV and the initial and final wavelength for every emission line detected e Scanning the velocity field of galaxy clusters allows determining emission line objects and even the cluster velocity dispersion e Scanning a certain emission line of a target of inaccurate redshift 3 6 2 7 synthesis technique 3 6 2 7 1 Technique As before but in this case the final destination is not analyzing images separately but adding them together providing a wider synthetic filter Figure 3 24 The main difference is that in this case one additional image must be obtained at the beginning and at the end of the scan in a conventional filter equivalence this would be similar to the zone where the spectral response 15 varying and the flat zone has not been reached yet and that the photometric accuracy refers to the wiggles generated when adding
90. ddddddd respectively depending on the entry in the first point 3 Centroid DEC coordinate 72000 The format is either in hours DD MM SS sss or DD ddddddd respectively depending on the entry in the first point Proper motion in RA in arcsec year Proper motion in DEC in arcsec year Slit type R for rectangular and C for circular holes Angle of the slitlet In degrees N for normal slitlets and F for a fiducial alignment target 5 Priority indication integer value 10 A target name or any other relevant information Page 101 of 148 USER MANUAL 0 Date January 1 2014 II PMRA KX arcsec year SIitType C RIV Fiducial Normal F N TargetName string sky RA HH MM SS sss DEC DD MM SS sss PMDEC XX xxx arcsec year Angle DD ddd Priority int Sky 16 59 31 80336 12 57 55 01160 1000000 00 00000 C 00 000 tgtUno sky 16 59 28 29600 12 56 21 57000 1000000 00 00000 C 00 000 tgtDos sky 16 59 26 33688 12 55 05 42280 1000000 00 00000 C 00 000 tgtTres Sky 16 59 2745552 12 52 01 35120 0 00000 00 00000 C 00 000 tgtCuatro Figure 7 6 Example of a target input list based on equatorial coordinates In what follows the basic steps are described about what one needs to do with the MaskDesigner tool To start the design begin with opening a new project by selecting from the File New MDP Setup the global parameters for the
91. degrees The shutter is incorporated in between the camera optics Light is detected by a mosaic of two detector of 2kx4k red optimized CCDs in a cryostat The instrument control subsystem allows mechanisms tunable filters and the detector to work in a synchronized fashion Also it provide users with mechanisms controls and data processing interfaces This instrument control is be closely integrated with the rest of Telescope Control following the GTC standards This facilitates a high level of automation of observing sequences OSIRIS calibration is performed using spectral lamps provided by the GTC Instrument Calibration Module ICM also external continuum lamps for dome flat fields are available at the telescope 1 1 2 OSIRIS focal plane masks The OSIRIS mask holder with 13 positions allows remote changes of focal plane masks such as spectrograph slits custom made multi object masks or other special purpose masks The following masks are available at the instrument e Long Slit masks Available slit widths are 0 4 0 6 0 8 1 0 1 2 1 5 1 8 2 5 3 0 5 0 10 0 e Decentred long slit of width for fast photometry in shuffle mode Figure 1 3 right e Mask of the central 1 3 imaging FOV for TF imaging shuffle two TF tunings or straddling line Figure 1 3 middle Frame transfer mask selecting 1 2 of the lines in both detectors Figure 1 3 left e Mask shading one detector for avoiding dithering
92. different contiguous wavelengths can be combined in the band synthesis technique Sec 3 6 2 7 e In the red spectral domain sky rings appear see Sec 3 9 2 3 9 1 Calibration images 3 9 1 1 Bias Images to correct for the electronic bias of the CCDs should be obtained and applied as usual These same readout speed and binning must be selected 3 9 1 2 Flat fields During the normal operation of OSIRIS at GTC flat fields for the TF observations are obtained using dome flat fields with the TF tuned to the same wavelengths of the science observations It 15 practically impossible to get a series of enough sky flat fields at all the wavelengths requested for a typical program due to time limitations Some features that can be observed at some wavelengths in the TF dome flats are also present in sky flat images hence they are not due to particularities of the dome illumination We consider that the dome flat fields are adequate for their purpose and little is gained from using TF sky flat fields The main features in the illumination pattern seen in the dome flats are also noted in the science images 10 As images obtained using different conventional filters would not be combined for this purpose either Page 59 of 148 Date January 1 2014 USER MANUAL V3 0 Figure 3 27 TF dome flat at 660 nm left and a sky image at 660 nm right obtained from an artificially dithered raw science image 3 9 2 Night sky emission line rings
93. distance to the optical centre 15 produced For example at the edge of the 8 arcmin diameter TF FOV the shift is of 7A for a dithering of 10 arcsec For those specific projects requiring more accuracy that use no dithering an additional chromatic term a3 A A 5 04r a A r 3 19 with a 6 1781 1 6024 10 4 41 0215 10 A where 4 is A allows obtaining accuracies of the order of the tuning error 1 within the whole OSIRIS TF FOV In the above expressions the distances r are not corrected for distortion 1 are before applying astrometric corrections igstrom 78 70 62 55 47 Wavelength 39 31 24 TQU m 2 00 72 95 510 3 25 3 40 T UNT STO 4 00 Arcmin Radius Figure 3 7 40 4 vs radius for different emission lines from the ICM spectra lamps covering the whole OSIRIS red TF wavelength range The curve is the equation 3 19 In red and green are the points that depart most from 3 19 corresponding to Hg Ar 7635A and Xe 91624 respectively 3 2 2 Blue Tunable Filter In the same sense for calibrating the wavelength dependence across the FOV for the OSIRIS blue TF images of different emission lines at different wavelengths covering the full OSIRIS BTF wavelength range were obtained For each emission line the blue TF was tuned at different wavelengths From these data the following wavelength dependence across the OSIRIS FOV is derived
94. e 80 of 148 USER MANUAL V3 0 Date January 1 2014 OSIRIS R2500U HgAr Xe calibration lamps 4358 328 Hgl 3 x 105 2x 105 4500 977 Xel 4524 680 4046 563 Hgl 4582 747 Xel 1 x 10 3650 153 Hgl 3600 3800 4000 4200 4400 4600 Wavelength angstroms OSIRIS R2500V HgAr Ne Xe calibration lamps 8 x 10 5460 735 5852 488 Nel id 5881 895 Nel 6 x 10 4x 10 5975 534 Nel 6029 997 Nel 5790 663 Hgl 2x 10 gt e N i v e gt e o e t 4624 276 Xel 4916 510 Xel 4923 152 Xel 4500 977 4524 680 Xel 4582 747 Xel __ 5769 598 Hgl X CN gt 4500 4750 5000 5250 5500 5750 6000 Wavelength angstroms Page 81 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R2500R HgAr Ne calibration lamps 7032 413 Nel Mv 90L IPN L28 88p7 IPN 668 8 V7 ION 296964 IPN 8 6 7L7 IeN 2976669 IPN r0 2129 IPN 926 51998 IPN 66 56698 IPN 866 9069 IPN 6606859 M t e IPN 88 G9 _ ION 8Ct PEI aN 687 FOES 6650029 IPN gooey NOS E919 59198009 ON BR 7668209 IPN PES 6766 IPN PES PROS IPN S68 L88S IPN 88p66
95. e Zoom Scale Color Region WCS Analysis Help Fie Edit view Frame Zoom Scale Color Region WCS Analysis Help pg Jani5 213609 fits CCD 2 L2 pg Jan5 214444 fits CCD 2 12 2 Object 2 Object 3 Value 1459 4 1910 wcs wes E Physical x 65 000 1227000 Physical x 57 000 Y 1387000 I image x 115 000 Y 1227000 Image X 107 000 Y 1387000 l Frame1 Zoom 0125 Angle 0 000 Frame Zoom 0125 Angle 0 000 X file edit view frame zoom scale color region wes help x file edit linear log power square root squared histogram min max zscale linear Figure 3 13 Example of intensity losses and resulting asymmetric slit image intensity profiles obtained for the same Z calibration scan in the following situations top left using Xbest 50 the Z scan is asymmetric and concave below the maximum intensity Top right using Xbest 50 the Z scan is asymmetric and concave above the maximum intensity Bottom left using Ybest 25 the Z scan is asymmetric and concave above the maximum intensity Bottom right using Ybest 25 the Z scan is asymmetric and concave below the maximum intensity Page 41 of 148 Date January 1 2014 USER MANUAL 0 3 5 2 Wavelength calibration 3 5 2 1 General considerations Parallelization is a day time procedure because it is very stable in time and even with temperature changes and instrument rotation Wavelength calibration on the other hand is a nightly procedure since t
96. e a single narrower filter This is due to internal reflections occurring in different layers of the filters that lead to the formation of ghosts Their intensity and position in the field vary depending on the combination of filters that 15 the position of the rotator etc This mode of operation 15 not offered OS657 OS666 57 0 OS785 OS838 OS858 05902 05910 05910 05919 OS878 05893 M Figure 3 29 Some examples of ghosts observed when using a combination of two contiguous OS Page 63 of 148 USER MANUAL 0 Date January 1 2014 4 MEDIUM BAND IMAGING SHARDS FILTERS From June 2012 the number of filters available for general use with the OSIRIS instrument has been drastically extended thanks to a generous gesture by Dr Pablo P rez Gonz lez from the Universidad Complutense de Madrid to make available his private optical filters Dr P rez Gonz lez designed and purchased using funding from the Spanish Government through projects CSD2006 00070 and AY A2009 07723E a set of medium band filters for the SHARDS science program that 15 currently being executed on the GTC for further details on this program see http guaix fis ucm es pgperez SHARDS This set consists of no less than 25 filters spanning the wavelength range from 500 to 940 nm with bandwidths from 14 to 34 nm Interested parties who would like to use of any of these filters should contact Dr P rez Gonz lez and GTC to request
97. e in the RTF Order Sorters definition produced on September 2012 OSIRIS RTF 24 1 2 2 8 TT 2 1 8 ata a a E a eb asa a s 46 55 T k ye T etn 1199 9 8 s as 8 P F E 8 1 g r x Pl s S A re Eg g a s pa a 660 BBO 700 720 740 760 780 B00 820 B40 860 880 800 920 940 A nm Figure 3 10 Available RTF widths vs wavelength for all the operative range of OSIRIS RTF The minimun width achievable 1s shown as a red line that is also the maximum width for gt 850 nm For the Blue Tunable Filter BTF the possible achievable pass bands are narrower than the ones provided by the RFT Due to the particularities of the only a single pass band 15 available for each wavelength that avoids contamination from other interference orders over the circular 4 arcmin radius field of view In other words for each wavelength only one passband FWHM 15 available The following table shows the available FWHM for the Page 37 of 148 USER MANUAL 0 Date January 1 2014 range nm available FWHMs nm 448 lt lt 464 0 80 464 lt lt 481 0 85 481 lt lt 503 0 80 503 lt A lt 522 0 50 522 lt lt 543 0 45 543 lt lt 584 0 50 584 lt lt 610 0 70 610 lt lt 638
98. e relevant to correct for precession proper motions and atmospheric refraction Hence the MaskDesigner automatically corrects for these effects and ensures that the physical location of the slitlets will be correct In case of doubt selecting and hour angle of O is normally a good choice Note that the slit angle is defined in sky coordinates independent of the instrument orientation Ignore the Telescope Offset boxes When you re done hit Commit changes and save the MDP file Next step is to set up the default slits and fiducial star holes For that go to File Configuration Config Default Slits where you can proceed to define rectangular slits circular holes used for the fiducial alignment stars and curved slit Note that curved slits are not yet supported For the rectangular holes you can specify the generic size as well as the typical wavelength range of interest and their generic orientation If the field orientation is set at 0 degrees then the slit angle would normally be set at 90 degrees These geometric details can later be tuned per slitlet if necessary The minimum supported slit width is 1 2 Page 102 of 148 USER MANUAL 0 Date January 1 2014 arcsec Similarly for circular apertures the diameter can be set Normally circular apertures are used for the fiducial alignment stars in the field and hence the tickbox fiducial should be activated The minimum radius for fiducial holes is 2 arcsec Just
99. e system X Y and the coordinate system of the physical mask that must be produced This requires a set of transformations and checks that the software takes care of in an automatic fashion based on the input given by the user The abovementioned transformations include the geometric field distortions and corrections related to atmospheric refraction the proper motions of objects and precession The software also ensures that there are no conflics between slitlets 1 e overlapping spectra manufacturing limitations that the slits fall onto the mask and that the spectrum 15 correctly projected onto the detector When designing a configuration of slitlets on the mask the MD avoids conflicts that may occur when spectra from different slitlets overlap It also shows how the spectra will be projected onto the detector The user is informed of any conflicts that may occur in the log window through a pop up window and in the graphical displays of the mask design Page 92 of 148 USER MANUAL 0 Date January 1 2014 Moreover the user can add priorities to slitlets so that the MD software can give priority to the highest priority slitlet and adjust the design accordingly The MD tool can be used to optimize and manage several masks at the same time which might be useful in large projects In fact the MD tool resolves conflicts by automatically demote slitlets that are inconflict to secondary masks However we advice users to start wit
100. e used in Long Slit Spectroscopic observing mode 3 8 OSIRIS Tunable Filters global efficiency The graph below shows the overall photon detection efficiency of OSIRIS Tunable Filters at GTC including the contribution both of the telescope and instrument optics system OSIRIS Tunable Filter Imaging mode Efficiency 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A Figure 3 25 Overall photon detection efficiency of GTC and OSIRIS with the Tunable Filters Page 58 of 148 USER MANUAL 0 Date January 1 2014 39 Post processing data The TF data reduction procedure 15 like that of narrow band direct imaging requires de biassing flat fielding combining dithered images if required flux calibration using aperture or PSF photometry of spectrophotometric standard stars and continuum subtraction 1f required The main differences with narrow band direct imaging are e For removing cosmic rays cosmetics or sky rings only dithered images at the same tuning Z can be combined taking care of the possible wavelength shift of the dithered images specially at the edges of the TF FOV see Sec 3 6 2 5 for some hints on alleviating this problem e Depending on the type of sources subtracting continuum images might be unnecessary if a pseudo spectra is obtained by aperture photometry of the sources observed at different contiguous wavelengths Sec 3 6 2 6 e Images of the same field at
101. ear log square root 3000 2000 1000 0 Figure 3 11 Example of a X calibration image of 14 steps of 50 bits Seen in the image is slit illuminated by an arc lamp The slit is centered on the field After each exposure the charge is shifted downwards the X setting of the TF changed and a new image of the slit is taken After a sequence of several steps the CCD is read out which results in a series of slit images as is shown here N note that in the X calibration the slit image intensities are not symmetric Page 39 of 148 Date January 1 2014 USER MANUAL 0 5 ds9 Hle Edit View Frame Zoom Scale Color Region WCS Analysis e g y File 02 044114 fits CCD 2 L2 3 4 3534 8 65 000 Y 1683 000 5 115 000 Y 1683 000 5 Zoom 0 125 Angle 0 000 x edit view frame x square root a 3000 2000 1000 0 8 4 Figure 3 12 Example of a Y calibration image of steps of 25 bits Note that in the Y calibration the slit image intensities are not symmetric 3 5 1 3 Lack of parallelism If the TF plates are not parallel the result will be e Distorted rings of the night sky emission lines and of calibration lamp lines e Asymmetric wavelength calibration Z scans that are in opposite directions depending whether there is an excess or lack in X or Y values see Figure 3 13 e Lower intensities of slit images in wa
102. econd example has much in common with the previous one except for the initial coordinates provided for the slitlets When you possess a set of accurate J2000 equatorial coordinates of your targets and fiducial stars you can input this list directly into the MaskDesigner tool and from there work to refine your mask design The MD allows you with its Sky Editor view to overlay your mask design on an image which has its astrometry well calibrated An important difference when working with equatorial coordinates as opposed to using a pre image is that in translating the J2000 input coordinates on the sky to the mask coordinates precession atmospheric refraction and proper motion are taken into account Before starting the design of a mask one has to prepare a target list with accurate coordinates This target list should include not only the science targets but also the fiducial stars Make sure that you have at least 3 fiducials 5 or 6 would be optimal that the fiducials are not too bright nor too faint as was described earlier and that they are well distributed over the whole field of OSIRIS Place the coordinates of all the targets in a text file alternatively you can use a spreadsheet tool such as EXCEL and save the file in CSV format containing the following columns 1 sky or skyDeg depending on the format of the coordinates see next points 2 Centroid RA coordinate 12000 The format is either in hours HH MM SS ssss or DDD
103. ectable This is done by using conventional filters called order sorters because they are used to select the required FPF order 3 1 4 OSIRIS TF Characteristics and Features The OSIRIS TF manufactured by IC Optical Systems with plate separations accurately controlled by means of capacitance micrometry has the appearance of a conventional Fabry Perot etalon in that it comprises two highly polished glass plates Figure 3 4 Unlike conventional COS etalons it also incorporates very large piezoelectric stacks which determine the plate separation and high performance coatings over half the optical wavelength range The plate separation can be varied between about 3 44m to 10 Page 29 of 148 USER MANUAL 0 Date January 1 2014 The highly polished plates are coated for optimal performance over 370 960 nm using two separate etalons one optimized for short wavelengths and one for longer wavelengths The coating reflectivity determines the shape and degree of order separation of the instrumental profile This is fully specified by the coating finesse N which has a quadratic dependence on the coating reflectivity The OSIRIS TF was coated to a finesse specification of N 50 red 100 blue which means that the separation between periodic profiles 1s respectively fifty one hundred times the width of the instrumental profile At such high values the profile is Lorentzian to a good approximation For a given wavelength c
104. ector It also avoids that spectra will overlap This tool takes automatically care of field distortions when mapping coordinates into the focal plane of the telescope More details are provided further down 7 3 MOS life cycle The complete process of planning and executing MOS observations becomes quite involved In order to design a mask the PI must have a list of target coordinates either from an existing catalogue with equatorial coordinates or based on pixel coordinates from a Sloan r band image taken previously with OSIRIS Hence it may be necessary to first obtain this pre image before the MOS observations can be planned In the case of using external non OSIRIS images it 15 strongly advised to check that the astrometric solution of such images is of sufficient accuracy typically for good results one needs astrometry better than 0 2 arcseconds Once completed the design of a mask or set of masks the resulting design file s may be sent to the observatory where the masks will be produced on a dedicated machine The observatory requires at least one full month to guarantee that the mask will be available in time The produced masks used or unused will remain in the possession of the observatory and are available for later re use Page 88 of 148 Date January 1 2014 USER MANUAL 0 Figure 7 2 Example of a sertes of spectra taken with OSIRIS using a MOS mask At the time of taking the observations the mask s are
105. efore the parameter of f sets to wcs An example of a resulting mosaic is shown below an astrometrically calibrated image of the Galactic cluster M67 with 2MASS point sources overlaid standard deviation of the fit 0 04 arcsec Figure 9 3 Example of OSIRIS mosaic 9 2 4 Composing a first order mosaic from raw data To create a mosaic from the raw frames of a scientific image valid up to first order proceed as follows assuming standard 2 x 2 binning e Create an empty fits image with 2110 x 2051 pixel e Rotate the CCDI frame in 0 02386 degrees around the pixel 525 0 1026 0 e Rotate the CCD2 frame in 0 04067 degrees around the pixel 525 0 1026 0 e Shift CCD2 in X 11 82013 and Y 1 64119 pixels Copy the CCD1 frame in the region 1 1049 1 2051 and the rotated CCD2 frame in the region 1050 2110 1 2051 of the empty image recently created e Apply the instructions above to obtain a WCS solution for the whole mosaic All this process can be executed in a direct way by using the preimaging MOS script see Section 7 6 4 1 Also note that from September 2012 a WCS solution is provided in OSIRIS FITS headers hence a direct WCS mosaicking is possible For a more precise astrometric solution please follow the instructions described in Sections 9 2 2 and 9 2 3 USER MANUAL 0 Page 120 of 148 Date January 1 2014 10 OSIRIS OS FILTER CHARACTERISTICS The following tables an flgures lists the complete OS
106. ensating for the centre to edge wavelength variation e Scanning a wide spectral line 1 that of a high redshift galaxy or a QSO 3 6 2 8 Summary 3 6 2 8 1 oources of instrumental photometric errors The sources of photometric errors of instrumental origin again please note that contributions of readout or photon noises must be considered aside are Page 56 of 148 USER MANUAL 0 Date January 1 2014 The FWHM of the TF depending on line width driven by velocity dispersion velocity field peculiar velocities and redshift This can be evaluated using Equations 3 25 or Table 3 1 and if appropriate can be corrected using the method of band synthesis Sec 3 6 2 7 The contribution of the line to the off band or to other lines to the on line image Can be evaluated using Equation 3 25 The wavelength variation across the target Depends on the size and the velocity field Can be evaluated using Equations 3 18 3 20 and 3 25 If required can be corrected using the method of band synthesis Sec 3 6 2 7 Dithering that varies the wavelength of pixels of the source from one image to a dithered one Can be evaluated using Equations 3 18 3 20 and 3 25 If required can be corrected using the method of band synthesis Sec 3 6 2 7 or choosing a suitable dithering pattern combined with TF tuning Sec 3 6 2 5 2 and 3 6 2 5 5 3 6 2 8 2 Preparing an observation a checklist According to the previous sections depending
107. entially keeps a record of warnings and errors that might come up during the design of a MOS mask Configuring the MD Once a mask design has been initiated some configuration parameters can be set Under Options menu one can activate the Project Options window where some details and defaults for the current design can be set It is useful to keep the default values and to enter the PI name It is not required to fill in the observation ID as this will be defined by the observatory after the design has been submitted for manufacturing Further specific details related to the mask design must be set under Configuration and then selecting Config Obs Here some basic configuration related to the OSIRIS instrument are set such as the dispersing element the detector binning factor whether the mask design 15 based on an OSIRIS pre image or uses a catalogue of equatorial coordinates etcetera Details on how this is used is explained in the examples that follow In the configuration panel the selected grism and filter combination set the spectral range of interest while the date is used to calculate effects of precession and proper motion while the hour angle is used to calculate the effects of atmospheric refraction In the case of using a pre image the relevant details are taken from this image itself The Offset entry allows the user to introduce an offset to the pointing coordinates in order to ensure that in the case of making a sky observati
108. ers Digitized Sky Version II at ESO and select the appropriate field of course for this example you need to be connected to the internet in order to access the on line catalogues The DSS image will appear together with your design and if all is well your slitlets should align well with the targets in the image Slitlets that for some reason are rejected by the MD tool show up in red Editing the properties of a specific slitlet can simply be accomplished by changing any of the input boxes First select a slitlet in the list Its properties will then show up and can be edited For instance the coordinates may be altered the slitlet might be given an angle its size changed or the wavelength range of interest adapted In the box labeled Target the proper motion of the target may be set or alterted The MaskDesigner calculates the movement for the epoch 2000 coordinates to the observing date set in the configuration Slitlets may also be deleted from the list by activiting the Delete Slit button Or the priority of a slit may be altered so that it 1s given the approriate weight when the MD tool optimizes the mask design When you are done with your design just save the Mask Design Project file by selecting File Save MDP and giving it an appropriate file name At a later stage you can reload this file and continue work where you left off Page 103 of 148 USER MANUAL 0 Date January 1 2014 8 OBSERVING WITH OSIRI
109. et playing with the possible variables e TF central wavelength for your ON and OFF images e TFFWHM e Position of the source in the FOV e Rotator position These points mark the difference with respect to direct imaging with conventional filters In other words in tunable imaging the design of an observation is extremely important as 15 the observing procedure is otherwise easily useless data can be the result In the following sections we provide derive recommended observing strategies depending on the type of sources and the scientific aims by explaining the impact of the previous parameters 3 6 2 1 Selecting off band wavelengths 3 6 2 1 1 Continuum subtraction In line imaging two images are usually required the on line image and the off line or continuum image The on line image has line plus continuum photons and the off line only continuum photons to be subtracted from the on line image to give the emission line continuum free image This can be done in two ways 1 Using the TF for line and continuum has the advantage that the spectral response and FWHM are identical and that you can select the continuum as nearby as desired from your line thus alleviating possible continuum variations with wavelength It is even possible using the technique of shuffled exposures Section 6 1 1 1 to on line averaging continuum on both sides blue and red of the line and averaging possible seeing and atmospheric variation In this
110. for creating a synthetic ring image by fitting an azimuthal average of the image and subtracting it e Fitting a 2D surface to the ring creating a synthetic ring image and subtracting it Synthetic ring images do not introduce photon noise in the final image as the other methods does 3 10 Medium Band Imaging with TF Order Sorters The TF Order Sorter filters can also be used for direct image observations Measurements made during the commissioning of OSIRIS January 2010 have provided zeropoint values for some of the most significant OS for the RTF These values are given in absolute magnitudes mag at airmass 1 using these measures of spectrophotometric standard stars OS map standard Zeropoint OS657 15 25 0 05 277 86 0 09 OS666 15 27 0 05 27 72 0 02 OS709 15 35 0 05 27 89 0 05 OS770 15 45 0 10 27 73 0 02 OS858 14 35 0 05 27 58 0 03 OS902 14 48 0 05 27 07 0 09 Please note that the OS are tilted 10 5 degrees to avoid ghosts due to backwards reflections from the detector therefore their central wavelength is shifted with respect to the nominal central wavelength with a drift in wavelength along the FOV following the tilting axis that 15 approximately the detector gap This 15 the same effect that was discussed in Section 2 1 2 for OSIRIS Sloan broad band filters but 1n this case the effect 1s more noticeable as the filters are narrower Page 61 of 148 Date January 1 2014 USER MANUAL 0 20
111. g the task daofind In IRAF noao digiphot apphot package specifying input image mean FWHM of image features to be detected as well as the detection threshold and standard deviation of the background Alternatively the SExtractor software Bertin amp Arnouts 1996 can be used for this purpose The Starlink GAIA software has the SExtractor embedded after loading any image it is possible to obtain a catalog of sources invoking the task Object Detection in the Image Analysis menu GAIA provides the facility to see the extracted sources on the image pick on a specific source and edit the output list You can also play with background parameters and re do detection extraction In both cases the required output is a list with x y logical positions here named xy cat e Construct a catalog with the reference positions of astrometric stars in equatorial coordinates for a defined equinox usually J2000 0 and epoch of observation 1 proper motion corrected coordinates This catalog is simply an ASCII file with an ID optional right ascension and declination in degrees here called radec cat It doesn t matter if the angular coverage of the catalog exceeds the OSIRIS field for a given detector e Match both files using IRAF imcoords ccxymatch The output file is radecxy cat an ASCII list with the matched coordinates in a suitable format to be used as input in the following task An example of the line command is ccxymatch xy cat radec
112. g to the standard pointing in Long Slit Spectroscopy mode X 250 in CCD2 as a guideline for the image reduction R250U HgAr Xe_ 6 00178 splin3 D Page 83 of 148 USER MANUAL 0 Date January 1 2014 6 5 3 Spectral flat fields Spectral flats can be obtained either by using dome lights or using the incandescent lamp of the instrument calibration module ICM ICM spectral illumination is rather inhomogeneous and has a strong gradient from CCD1 to CCD2 For this reason spectral flats obtained with the calibration unit are only recommended for targets placed in CCD2 There are no significant dependences in the spectral flats with instrument rotator angle Therefore as with the arc lamps the spectral flats for each observation can be taken at the beginning or at the end of the night regardless of the position of the rotator 6 6 VPHs R2000 R2500 ghosting The R2000 and R2500 VPHs suffer from a faint ghost image of the spectrograph slit that normally will have a negligible impact on the quality of the spectra The ghost 15 negligible in the R25001I and R2500R VPHs while in R2000B R2500U and R2500V the ghost is only noted in the spectral flat field images and arc lamp frames where a very faint slit image can be observed superimposed on the spectral flat lamp arcs The approximated position for those ghost Images are R2000B from pixels Y 988 to 996 R2500U from pixels Y 980 to 988 R2500V from pixels
113. ge headers If a different position angle P A is requested by the user the resultant IPA would be 150 540346 P A with P A measured from N to E Page 12 of 148 USER MANUAL 0 Date January 1 2014 The OSIRIS focal plane is imaged by two CCDs that have a narrow gap between them This gap is 9 4 arcsecs wide To cover the full field when defining a dithering pattern steps of 10 arcsecs or even 12 arcsecs to be more conservative perpendicular to the gap are recommended 1 1 7 Instrument overheads During instrument design special efforts have been invested in reducing instrument overheads due to configuration changes observing modes masks and filters or grisms to the minimum The following table summarizes the typical time it takes to change a component Mask change Filter Change Grism Change 60 sec 10 sec These times only reflect the mechanical changes of the components and not the overheads for target acquisition in the different modes auto guiding and detector readout Changing form one TF to the other takes about 13s Changing TF wavelength tuning takes at most about 0 1 s usually 0 02 s depending on the gap differences between the different tunings 1 1 8 Environmental conditions OSIRIS is protected from the environment through its fairly air tight enclosure Dry air flushes the instrument to avoid dust and moisture entering the instrument and depositing on optical surfaces This air 15 provided by
114. h angstroms 6000 5000 snay xn 3 Page 135 of 148 en gt lt Z lt gt 24 un Date January 1 2014 OSIRIS R300R Ne calibration lamp e 10000 9000 96 6988 798 688 I9N S 2828 ION 955 56 8 I9N 909448 I9N 9C 00 8 I9NS0T 9718 I9N 86 C808 ION 181 164 I9N bis 448 594 I9N 29 Sv CZ 8000 Wavelength angstroms I9N 8 6 412 7000 I9N 2916269 IN V0 ZL29 9228799 9 ZZ8 Z S9 9269059 56 8659 I9N 8bZ ZO v9 ION 8CV 9 Jan 9929 I NT6S 919 19 890 9 9 2919609 19 8227209 I NT S SZ6S 9 8 VV 6S 9 5681885 I N 8872585 snay xni4 1 319 6000 5000 OSIRIS R300R Xe calibration lamp 8819 411 Xel 6 66 0 6646 lex S 9 LESS sav 1 10000 9000 8000 Wavelength angstroms 7000 6000 Page 136 of 148 en gt lt Z lt 24 un Date January 1 2014 OSIRIS R500B HgAr calibration lamp D LO M e lt LO 11 1 9 Pers MV ol 2048 ccs v9c8 SP L 8r62 86 c24Z 11 90 5694 11 ZS9 PLSZ 698 097 11 865864 11 9 6 224 11 8LZ 7907 11 Lev 969 DH 99 0646 9656926
115. h designing individual masks in order not to complicate the designs when dealing with complex arrangements Moreover the observatory only will accept design files for a single mask that each is associated with specific observing block Before starting with the design of an OSIRIS MOS mask the user must either have a set of accurate equatorial J2000 coordinates prepared or a set of accurate x y pixel coordinates based on an OSIRIS Sloan r band image pre image mode When using an OSIRIS image the MD can be used to interactively select the objects based on the image The MD allows the user to visualize the end result of the masks Mask designs can be stored and reloaded at a later moment Slitlet details can be edited on line for instance for making small adjustments All details of a design are stored in an MDP file Mask Design Project file When a design is completed one must save the end result as a so called MDF file Mask Design File This file will be used as input by the observatory to manufacture the mask accrding to the design 7 6 3 graphical user interface After starting up the MD two windows appear a log window and the main window that acts as the main interface with the user from where all actions are activated The log file can be consulted at any time but plays no active role during the design process The main window consists of the following areas indicated in Figure 7 3 Pull down menu options 2 Box p
116. hanges in plate spacing d correspond to different orders of interference m This in turn dictates the resolving power mN according to the finesse Figure 3 4 OSIRIS red etalon at the IAC Optical Lab while undergoing calibration tests In general as can be appreciated in Eq 3 2 for a given order small changes in d change slightly the wavelength while for a given wavelength the change of order requires a larger change in d This is important to keep in mind Page 30 of 148 USER MANUAL 0 Date January 1 2014 With very good approximation the spectral response of a given by eq 3 1 can be expressed by 2 T 2414 3 14 On where is the wavelength at maximum transmission 1 0 0 9 0 8 0 7 0 6 0 5 0 4 Tunable filter Gaussian Transmission 0 3 0 2 0 1 0 0 0 565 0 570 0 575 Wavelength Figure 3 5 Spectral response of TF wrt a Gaussian The TF response can be considered Gaussian with a good approximation above FHWM but is more winged below FWHM This has to be taken into account when selecting the on and off frequencies 3 1 4 1 Dimensions The OSIRIS TF are model ET 100 Then the clear aperture is 100 mm diameter The units are approximately 170 mm diameter by 100 mm of thickness and have a weight of approximately 8 kg 3 1 4 2 Coatings This 15 a critical aspect of TF performance as shown in section 3 1 1 Fo
117. he Z A calibration depends upon many factors and the calibration must be checked during the night even for the same wavelength and order The wavelength calibration consists of establishing the relation between Z values in bits and the wavelength This relation is non linear enough so that a linear approximation can be deemed valid only locally Through tests of the TF carried out under controlled environmental conditions the relation between Z and wavelength has been derived for every order and through the full wavelength range that each TF can cover Extensive tests show that The A Z curve may be offset in Z by a constant factor depending on the environmental conditions with a precision of 5 bits in Z 1 better than O 1nm However it is necessary to determine the offset for Z mimicking as closely as possible the true observing conditions So in essence wavelength calibrating the TF consists of determining this offset This is done at the telescope by using a calibration lamp of the ICM SAOImage ds9 lt amp e File Edit View Frame Zoom Scale Color Region WCS Analysis File Jan15_211802 fits CCD 2 L2 2 Object 2 Value 1649 WCS 5 Physical x 49 000 Y 1227 000 5 Image x 33 000 Y 1227 000 ag Frame 1 Zoom 0 125 Angle 0 000 x file edit view frame linear log square root Figure 3 14 Z calibration scan 20 slit images can be seen The first one is the bottom one The tuning lies between image 11 and 12
118. he centre Then the wavelength corresponding to the zero redshift Ho at this position is not 656 3 nm but 656 8 nm Please note that 250km s is the FULL velocity field not the velocity field FWHM Please do not forget this detail Page 51 of 148 USER MANUAL 0 Date January 1 2014 Even with the above strategy and unless the target is very small the wavelength dependence across the FOV will produce that some parts of the target are observed at different wavelengths The induced photometric error can be evaluated using Equations 3 18 3 20 and 3 25 For example for the same example above the wavelength of the edge of the target near the TF centre is 656 8 nm and the wavelength at the edge of the target in opposite direction 1s 654 7 nm The photometric errors induced by this line decentring are respectively 7 and 45 from Equation 3 25 if a FWHM of 3 5 nm is assumed Then it is possible to choose a TF tuning wavelength that minimizes this variation when the wavelength difference at both edges of the target is the same For example tuning at 657 3 nm gives a photometric error equal at both edges of the target and of the order of 25 Of course the velocity field of the target must be taken into account in this procedure since it increase the photometric errors if the velocity field 15 known it is possible to adjust the target and rotator position to minimize it Were this photometric error too much it
119. he detector is directly related to the slit position in the field The Mask Designer tool that 15 described in detail further on assists the user in optimizing the design and produces a design file that is used for producing the mask The success of MOS observations depends critically on having accurate coordinates of the sources of interest together with those of a number of appropriate stars in the field specially selected for alignment purposes the fiducial stars Intrinsic errors in coordinates effects of proper motion systematic differences between catalogues and effects due to differential refraction by the atmosphere must be controlled for MOS observations to be successful Users of MOS mode must pay special care to these aspects Page 87 of 148 Date January 1 2014 USER MANUAL 0 Figure 7 1 Mask driller machine available at the GTC for MOS observations If the fiducial stars work well alignment of a slit mask on the sky takes a similar amount of time as aligning a long slit mask Hence the overheads in MOS mode are similar to those for normal long slit spectroscopy with OSIRIS For the design of slit masks a special software tool the OSIRIS Mask Designer MD must be used This tool allows the user to input a coordinate list either equatorial coordinates or coordinates on the CCD pixel scale of OSIRIS and to optimize the position of the slits The Mask Designer shows where the spectrum will be projected onto the det
120. hutter did open Only appears if the shutter actually moved that is does not appear in bias images Position of optical center in the X direction Position of optical center in the Y direction Original FITS file name Page 113 of 148 USER MANUAL 0 OSFILT OSISTAT OSIVERS OSWAV OUTMODE PCOUNT PI PRESCAN PRESSURE RA RADEG RADESYS READTIME ROI X 4500 TWOCCDS A mespinoza true 777 289978027344 9 35 13 247 143 805 19462267 FK5 05 35 17 972 2098 Date January 1 2014 Order Sort Filter identifier N A OSIRIS status N A ok OSIRIS software and hardware version Order Sort Filter central wavelength 5 OutputMode N A required keyword N A must 0 Personal N A Investigator Prescan active or Boolean not Ambient atmospheric pressure hPascal hectoPascal Telescope ascension HH MM SS h m s right HH MM SS sss Telescope ascension decimal deerees right in Degrees Equatorial N A coordinate system time Approximate HH MM SS when read starts X Size of windows Unbinned in pixels Pixels Order Sort Filter identifier Flag to indicate osiris status 1 OSIRIS software and hardware version Order Sort Filter central wavelength CCD readout output mode Size of special data area Principal investigator of the project for which the observation was taken Whether the presca
121. ients are normally far smaller In the future the instrument control system will take care of this effect at user s request Instrument rotator angle The calibration of the TFs is highly dependent on the angle of the rotator and hence on the orientation of the TFs We can find differences of up to 40 bits 8A between two rotator positions see Figure 3 15 In order to avoid this we define for TF operation the following useful range 160 lt 0 lt 40 and 50 lt 0 160 This range ensures a stable calibration accuracy of 0 1 and if the rotator is moving less than 10 the calibration can be considered virtually unchanged with the precision given by the self calibration 0 02nm 1 bit The global variation 15 the blue tunable filter is roughly inverse of the behavior of the red tunable filter as gravity induced flexure in the reference capacitors is opposite given their opposite location in the filter wheel During the normal operation the observer predicts in advance using the coordinates of the object and its instrument position angle the position of the rotator to a specific time in order to ensure that the observations are performed in the optimal range This variation is independent both of wavelength and distance between plates 7 TF history if plates collide the TF calibration might change This is unlikely to happen since the Z range has been limited to safe values However caution must be taken when o
122. ight choices The process can however be time consuming depending on the quality of information that one has available at the outset There are a number of aspects in the design that require special attention From the outset one has to have clear whether the mask will be designed based on a set of accurate equatorial coordinates coordinate design method or on the basis of pixel coordinates taken from an OSIRIS image pre image design method The necessary steps for both design methods will be described in detail in the next session Page 90 of 148 USER MANUAL 0 Date January 1 2014 When designing masks based on equatorial coordinates great care has to be taken with the quality of the coordinates which is all important for a correct design The user should be aware of effects like intrinsic uncertainty of the coordinates proper motions and systematic differences between catalogues Note also that only J2000 coordinates should be used In the case of designing a mask based on an image taken with OSIRIS pre imaging mode one must have access to a suitable image of OSIRS taken in the Sloan r filter Other filters may introduce unexpected field distortions Images taken with the tunable filter for instance are not valid as input for designing MOS masks The raw pre image containing the two CCDs must first be converted into a single mosaic that contains the images of both CCDs correctly positioned so that the pixel coordinates
123. ining those windows All the windows must have the same size e Nooverlap is allowed between different windows Windows must be defined in increasing order of their Y coordinate that coincides with the readout direction Therefore Y coordinates for different windows must not overlap for example if a window is defined at 1 200 300 499 any other window must begin at Y 500 or conclude at Y 299 e Windows are replicated in both CCDs Hence if N windows are defined in CCDI the same windows will appear in CCD2 with the same size and position as those of CCDI Some cross talk has been noted between windows in both CCDs for this reason is highly recommended that only use a single CCD when using windowing in OSIRIS The readout speed in windowing mode 15 defined by the combination of the windows size and CCD readout mode When windows are read out the CCD section unused is split at the highest readout speed hence there is no dependence in the total readout time on the windows location in the CCDs In any case if the user is interested in observing with OSIRIS by using windows please contact well in advance a GTC staff astronomer in order to choose what is the most convenient setup for the observing program At the telescope the GTC staff astronomer will perform the observations and all the restrictions and particularities in using the windows will be properly considered Page 17 of 148 USER MANUAL 0 Date Januar
124. installed in OSIRIS Only a small number of masks can be installed at any one time When the field 15 being acquired the fiducial stars have the function of correctly aligning the mask with the projected star field This alignment process again relies on information provided in the mask design file When a good alignment is obtained then the exposure can start 7 3 MOS mode practical limitations As was indicated before the successful use of MOS masks stands or falls with having accurate coordinates of a number of stars for aligning the mask on the sky and of the science targets Especially the positions of the fiducial stars are crucial as any error in these stars will translate to a poor positioning of the whole mask For the fiducial stars circular holes must be used on which the mask can be centered At least three fiducial stars are needed but we strongly advice users to allow for more stars for instance six Special care should be taken with the proper motion of these stars although often this 15 not known This 15 one of the key reasons to define several fiducial stars so that one or two stars that happen to have a high proper motion can be identified and omitted when aligning the mask Of course when the target pixel coordinates are used directly from an OSIRIS image proper motion should not be a concern Holes for the fiducial stars should have a diameter of no less than 4 arc seconds Also the brightness of fiducial stars is crucial
125. inting position for OSIRIS Broad Band imaging pixel 250 1024 in CCD2 This latter can be as much as 5 6 nm bluer than the central wavelength at CCDI reaching differences up to 12 14 nm at the extremes of the FOV Taking into account that most SHARDS filters have a bandwidth as narrow as 17 nm except in two cases this produces that the wavelength range observed in OSIRIS CCD1 can be notably different than the one observed in OSIRIS CCD2 Hence for instance when making use of the whole FOV of OSIRIS for mapping a single emission line probably more than one filter has to be used e o C Em j Un E gor z 00 Jg Lm D Ce Ce M 00 radius arcmin Figure 4 1 Central wavelength variation along the OSIRIS FOV for SHARD filter U840 17 Page 65 of 148 USER MANUAL 0 Date January 1 2014 An example of this effect is shown in Figure 4 1 for filter U840 17 filter The central wavelength in CCDI is 843 nm while the nominal wavelength for an angle of incidence of 10 5 is 840 nm approximately at the central gap between CCDs For CCD2 the central wavelength changes drastically from 840 nm to 830 nm at the edge of OSIRIS FOV a value that is 13 nm bluer than the central wavelength in CCDI The central wavelength variation has been calibrated for each filter and can be represented by the following function CWL X Y A Bx X X 4 1 were X Y are the positions in
126. is possible to synthesize a wider FWHM by adding TF scans see 3 6 2 7 Figure 3 21 Changing rotator angle is useful for minimizing the wavelength variation across the target 3 6 2 5 Removing ghosts cosmic rays and cosmetics One feature of etalons is that they produce ghosts In any astronomical instrument the detector is a source of light any light that is not detected or absorbed 15 reflected This light reflected by the detector follows the same optical path in opposite direction entering the etalon and reflecting in the most reflective surface i e that of the reflective coating of the etalon cavity going back and hitting the detector in a place symmetric with respect to the optical centre of the etalon This has three important implications for the observer Page 52 of 148 USER MANUAL 0 Date January 1 2014 1 Diametric ghosts are symmetric with respect to the centre of the etalon Figure 3 22 that in the case of OSIRIS is almost the centre of the OSIRIS field in the gap between detectors at the line 976 binned coordinates 2 Diametric ghosts can be easily removed by the classical dithering procedure since moving the image in one direction shifts its ghost in the opposite direction with respect to the TF optical centre When stacking up the images taking as reference the image of the target all ghosts fall in different pixels and can be removed with average sigma clipping of similar algorithms 3 Only
127. kHz 9 5 binning 2 x 2 are Sky Brightness Sky Brightness Sky Brigthness u BRIGHT GRAY DARK Page 20 of 148 USER MANUAL 0 Date January 1 2014 Although ETC predictions for sky brightness at the ORM are accurate enough it is recommended to use the values from the table above for a quick estimation of the sky background counts in long exposed images to avoid possible sky saturation 2 1 1 3 Colour corrections Photometric transformations equations with an arbitrary zeropoint of 25 magnitudes are u uo 0 657 0 053 0 071 0 023 uo go g o 3 763 0 040 0 078 0 013 go ro r r g 4 197 0 017 0 1 14 0 028 ro 10 1 10 3 770 40 015 0 079 40 041 io zo z o 3 201 0 031 0 072 40 052 io zo 2 1 1 4 OSIRIS GTC Broad Band Imaging efficiency The graph below shows the overall photon detection efficiency of GTC and OSIRIS in each of the Sloan filters the plots include the contribution both of the telescope and instrument Optics system OSIRIS Broad Band filters 0 45 Efficiency 0 3000 4000 5000 6000 7000 8000 9000 10000 wavelenath A Figure 2 3 Overall photon detection efficiency of GTC and OSIRIS in each of the Sloan filters Page 21 of 148 Date January 1 2014 USER MANUAL V3 0 Also the following plots shows the lmiting maenitudes with OSIRIS Sloan filters for gettine S N 3 as a function of the expos
128. kHz for imaging and RON 45e 200 kHz spectroscopy amp 500 kHz for acquisition 8e 500 kHz Gain ADU Linearity For 196 to 9096 full well see Figure 1 5 Operating Temp Dark current CTE Measured on grade 5 at laboratory Horizontal 20 9999 Binning Nominal is 2 x 2 Windows Copied on both detectors Frame transfer Enabled For fast photometry amp Spectroscopy 3 900nm Fringing starts between 850 and 900 nm Fringing 2 950 nm Measured on grade 5 device at laboratory 4 990 nm Using two channel per detector requires obtaining all images in this configuration and slightly different biases per channel 1 e half detector are obtained At 950 kHz the RON is so high that the image is not of scientific use and at speeds lower equal than 100 kHz the readout time increases at a cost of no significant reduction of RON RON 500 kHz is higher than nominal 8 likely due to EMI as of February 2010 Readout times can be evaluated in the following way Pixels to read readout speed x binned pixels x channels used For example reading both 2k x 4k full detectors using two channels per detector with 2 x 2 binning at 500 kHz takes 2 s Please note that this does not consider the time invested in configuring the SDSU about 5s clearing the chip before each exposure about 4s and transferring and saving the frame on disk few more seconds Then since an image 15 started till 15 fully acquired for the t
129. l axis of the instrument Because of the angle the central wavelength A 10 is shifted with respect to the nominal central wavelength 0 and the bandwidth AA changes slightly but the transmission curve shape is hardly altered Furthermore depending on the location in the focal plane the light incident on the filter cover a range of angles between 2 y 22 with the corresponding shift in wavelength For the broad band filters this effect 1s small as can be seen in the following table 3 Note that those coordinates are binned coordinates that is the standard operation mode of OSIRIS When 1 x 1 binning is used those values have to be doubled Page 18 of 148 Date January 1 2014 USER MANUAL 0 The maximum spatial variations of the filters with respect to the centre are A A 76 oe eod oge 30 4 10 _ J 1399 The absolute spectral responses for each filter except are provided in Figure 2 1 Transmission 96 Transmission 96 050 400 450 500 550 600 Bao 550 600 650 700 750 Wavelength nm Wavelength nm Transmission Transmission 96 B50 700 750 800 850 900 800 850 300 950 1000 1050 1100 Wavelength nm Wavelength nm Figure 2 1 From left to right and top to bottom measured central spectral response of g r 1 and z filters respectively with normal incidence Page 19 of 148 USER MANUAL 0 Date January 1 2014 2 1 1 1
130. le reflections Figure 3 1 with the amplitude and phase of the resultant beams depending on the wavelength At the resonant wavelengths the resultant reflected beam interferes constructively with the light reflected from the first plate cavity boundary and all the incident energy in the absence of absorption is transmitted At other wavelengths the FPF reflects almost all of the incident energy 3 1 1 1 Performance of an ideal FPF The general equation for the intensity transmission coefficient of an ideal FPF perfectly flat plates used in a parallel beam as a function of wavelength is si T 4 io 3 1 1 8 1 R 4 where T is the transmission coefficient of each coating plate cavity boundary R is the reflection coefficient d is the plate separation is the refractive index of the medium in the cavity usually air 4 1 and 8 is the angle of incident light Thus the FPF transmits a narrow spectral band at a series of wavelengths given by mA 2 cos 3 2 where m is an Integer known as the order of interference The peak transmission of each passband is Z 2 T max 5 2 3 3 x I R T A where A is the absorption and scattering coefficient of the coatings A 1 T R Page 24 of 148 USER MANUAL 0 Date January 1 2014 Therefore the contrast between the maximum and minimum transmission intensities 1s 2 T C 3 4 r T R r min For a FPF con
131. lescopes both ground based and aboard satellites Figure 1 1 3D of OSIRIS showing the main subsystems Page 7 of 148 USER MANUAL 0 Date January 1 2014 OSIRIS 1s directly attached to the GTC field rotator and guide unit in the Nasmyth B focal station Figure 1 1 The instrument optics are designed around the classical concept of collimator plus camera For reasons of keeping the instrument compact the optical train 15 folded and the field is off axis Its compact design will allow future migration of the instrument to the Cassegrain focal station Next we will briefly describe the main components of the instrument following the light path from the moment the light coming from the telescope enters the instrument through a transparent entrance window A masks loader Figure 1 1 selects and insert remove masks to from the telescope focal plane In addition to user customized masks for multi object spectroscopy a number of fixed width long slit masks are available as well as a number of special masks to facilitate fast photometry and charge shuffling see 1 1 2 Having passed the focal plane the light reflects of the collimator Figure 1 1 which is an off axis quasi parabolic mirror with elements for support and adjustment The collimator 1s open loop actively controlled to compensate for gravitational flexures of the instrument Figure 1 1 The collimated beam next hits a flat fold mirror that directs the light
132. m matrix element 1 2 element 1 2 CD2 1 3 47495198 05 WCS matrix World coordinate system matrix element 2 1 element 2 1 WCS matrix World coordinate system matrix CD2 2 6 1519739E 05 elementa degrees pixels element Time the OSIRIS shutter close CLOSTIME 12 23 17 593 Shutter Time HH MM ss appears if the shutter actually moved e g does not appear in bias images COMMENT This is a comment None N A Keyword doe comments of whatever nature Pixel in image corresponding to CRPIXI 462 5 Ref pix of axis 1 pixel the RA given by CRVALI CRPIX2 995 23 Refpixofaxis2 pixel ponding 1o the DEC given by CRVAL2 RA at Ref pix in This is the Right ascension of the CRVALI 1 55213538050385 degrees decimal degrees pixel given in CRPIXI DEC at Ref pix in This is the declination of the decimal deerees pixel given in CRPIX2 TF Auto Same as EKW16 Default value CSCXOFF 34680 Adjustment X Encoder units of TF X position set at starting encoder units time TF Auto Same as EKW17 Default value CSCYOFF 34680 Adjustment Y Encoder units TF Y position set at starting encoder units time Page 107 of 148 USER MANUAL V3 0 Date January 1 2014 TF Auto Same as EKWIS Default value CSCZOFF 34680 Adjustment Z Encoder units jof TF Z position set at starting encoder units time hot ec System used for world coordinate CTYPEI RA
133. n value are found Day to day fluctuations in the flat fields are less than 0 05 and less than 0 1 week to week Hence sky flat fields obtained with OSIRIS are well usable up to within a week before or after the observations Comparison twilight flat fields with those derived from scientific observations during bright time shows no variations in excess of 0 01 hence they can be considered practically identical for scientific purposes These percentage variations are measured globally while of course locally due to dust particles that can come and go the variations may be larger Moreover differences between the night sky and the twilight spectrum may result in subtle flat fielding differences Comparisons between fky flat fields and dome flats show that the latter suffer from inhomogeneities in the dome illumination Differences up to 10 15 are found in CCD2 and 2 in CCDI Therefore dome flats are only recommended for obtaining reliable OSIRIS photometry in CCD1 and as last choice in CCD2 As a product of the scientific operations with OSIRIS a series of master flat fields frames can be retrieved from http www gtc iac es instruments osiris osiris php zBroadBand Imaging Flat fields were all obtained with exposure times larger than 1 s to minimize possible photometric effects due to OSIRIS shutter and a maximum exposure time of about 20 s where the detection of stars becomes notable with an average of 35 000 40 000 ADUS in ea
134. n was active or not Ambient atmospheric pressure Telescope right ascension Telescope right ascension In decimal degrees Reference system for World Coordinate System Approximate time when read starts NOT CLEAR X Size of the CCD area actually readout unaffected by binning Equal to the whole CCD except when using windows Page 114 of 148 USER MANUAL 0 Date January 1 2014 Y Size of area actually Y Size of windows Unbinned readout unaffected by binning ROI Y 4102 in pixels Pixels Equal to the whole CCD except when using windows T X of lower left corner position of ROI 1X 0 pusqa the window Unclear description i what is RDI RDW Los Y of lower left corner position of ROI 1Y 0 the window Unclear description what is RDI RDW If a second window is defined X Origin of ROI 1 i ROI 2X 0 in RDLRDW Pixels this is its X of lower left corner position IH second window 15 defined Y Origin of ROI 1 j 2 0 in RDLRDW Pixels this is its Y of lower left corner position ROTANG 61 8845 SOME poston Degrees Rotator position angle in degrees angle in degrees RSPEED 100 Readout Speed Khz CCD read out speed in kHz SEQUENCE SIMPLE o A N A CCD read out sequance mode Whether the file conform to fits standard file does conform to SIMPLE T FITS standard Boolean Should be always 0 Data are SIMVAL 0 Simulate Val N A
135. nd depends on Z and OSIRIS TF Parallelism is very robust and does not vary with time even when switching off and on again the TF controller Hence once the XY values for a certain Z and range are determined they can be used around these Z and A values from then on Checking parallelism values from time to time 1s recommendable Page 38 of 148 Date January 1 2014 USER MANUAL 0 3 5 1 2 TF parallelization procedure This parallelisation procedure for the TF is a task to be done during the day The basis consists of maximizing the intensity of the light in the optical centre of the TF when tuned to the wavelength of an emission line from a calibration lamp while varying X and Y This 15 the same procedure to be employed for wavelength calibration but then varying Z A lack of parallelism XY or a poor of wavelength tuning Z will reduce the intensity measured This procedure is achieved by inserting a wide centred long slit and stepping the charge on the CCD while varying X Y or Z in a systematic fashion The TF must be tuned to the wavelength of an emission line 1 e the Z must be the one corresponding to the emission line gt v SAOImage ds9 6 File Edit View Frame Zoom Scale Color Region WCS Analysis File Jan02_043907 fits CCD 2 L2 Object Value 599 WCS Physical x 73 000 1523 000 Image x 123 000 Y 1523 000 Frame 1 Zoom 0 125 Angle 0 000 lt gt lt wuwwu V file edit view frame lin
136. nstein 1984 PASP 96 530 Oke 1990 AJ 99 1621 Stone 1977 ApJ 218 767 Oke 1974 ApJ Supp 27 21 Massey 1988 ApJ 328 315 Oke 1990 AJ 99 1621 Bohlin et al 1995 AJ 110 1316 Hamuy et al 1994 PASP 106 566 Hamuy et al 1992 PASP 104 533 Oke 1974 ApJ Supp 27 21 Massey 1988 ApJ 328 315 Stone 1977 ApJ 218 767 Massey 1988 ApJ 328 315 Oke 1990 AJ 99 1621 Massey 1988 ApJ 328 315 Oke 1974 ApJ Supp 27 21 Oke 1990 AJ 99 1621 Bohlin et al 1995 AJ 110 1316 Page 147 of 148 USER MANUAL 0 Date January 1 2014 GRW 70d5824 13 38 51 87 70 17 08 5 GD190 15 44 20 0 18 06 7 BD 33d2642 15 51 59 86 32 56 54 8 Ross 640 16 28 25 03 36 46 15 4 PG1708 602 17 09 15 9 60 10 10 Grw 70 8247 19 00 10 25 70 39 51 2 G24 9 20 13 55 7 06 42 45 LDS749B 21 32 15 75 00 15 13 6 GD248 23 26 06 59 16 00 19 6 Feigel10 23 19 58 39 05 09 55 8 7 14 7 10 81 13 8 13 9 13 1 15 8 14 67 15 1 11 82 320 920 nm 320 1000 nm 320 920 nm 320 1000 nm 320 800 nm 340 920 nm 320 1000 nm 320 920 nm 320 1000 nm 320 920 nm Oke 1990 AJ 99 1621 Oke 1974 ApJ Supp 27 21 Oke 1990 AJ 99 1621 Oke 1974 ApJ Supp 27 21 Massey 1988 ApJ 328 315 Oke 1974 ApJ Supp 27 21 Oke 1990 AJ 99 1621 Filippenko amp Greenstein 1990 PASP 96 530 Oke 1990 AJ 99 1621 Oke 1990 AJ 99 1621 Filippenko amp Greenstein 1984
137. ntific spectra Blue Tunable Filter BTF calculations are still in progress please contact with GTC SA staff for estimates for the BTF 8 2 GTC Phase 2 tool Observations with OSIRIS GTC can be done both in queue or visitor mode but in any case observers must use the GTC Phase 2 tool in advance to prepare the observations In queue mode this is mandatory in order to provide to GTC SA staff with the instructions for completing the observing programmes in visiting mode this is highly recommended as the Phase 2 tool allows to the GTC SA staff to generate automatized observing sequences at the telescope hence notably increasing the nightly operating efficiency For a complete help in how to use and complete this GTC Phase 2 tool users are referred to the on line help document available at http gtc phase2 gtc 1ac es science media docs phase2help pdf For other overall details in GTC queue observing mode please read carefully the section Observing with GTC at GTC web pages http www gtc iac es observing observing php Page 104 of 148 USER MANUAL 0 Date January 1 2014 9 OSIRIS DATA PROCESSING 9 1 OSIRIS GTC Keywords Data files produced by OSIRIS on GTC have a standard FITS structure In the standard Operative mode of the instrument both CCDs are read using a single amplifier Data corresponding to each CCD are stored as independent subdimensions of the image The filenames have a structure which contains
138. on for calibration purposes with the same mask that no stars by coincidence enter the slits When having made changes one has to click the button Commit changes to activate them This causes to program to re calculate the current design Configuring the default slit shape When designing a mask the MD tool assumes a built in default shape for the slitlets This default is set in option Config default slits in section of Configuration In this configuration panel you can set the default type of slitlet being either rectangular circular or curved In this same panel the sizes and relevant wavelength range can be set These default settings can be overruled for individual slits in the main panel Page 97 of 148 USER MANUAL 0 Date January 1 2014 Configuring the spectral range Each slitlet projects a spectrum onto the detector and obviously spectra from slitlets must not overlap or be projected outside the detector The MaskDesigner tool is set up to detect and prevent overlapping spectra and allows the user to change the slit properties to avoid conflicts The software also warns the user when spectra fall outside the detector However it could happen that the user 1s only interested in a limited part of the spectrum in which case it may be acceptable when spectra partly overlap or are projected outside the detector as long as the interested part remains detectable Therefore the MD allows the user to specify for each slitlet
139. or any broad band filter measured distortions are similar OSIRIS Field Distortions No filter pixel x 5 4000 4000 3000 3000 2000 1000 1000 Qm cou lt ELM IL m E F x xk bab EE lh 500 1000 1500 2000 500 1000 1500 2000 Detector 1 Detector 2 Figure 9 1 OSIRIS Field distortion without filters Obviously the non linear components of an astrometric solution for both detectors are not negligible For this reason a general scheme linear terms plus distortion must be chosen to find a solution with sub pixel precision An example of a ccmap task command could be the following ccmap radecxy cat image db images image results image res xcol 3 1 4 lngcol 1 latcol 2 lngunits degrees latunits degrees insystem j2000 refsystem j2000 projection tnx fitgeometry general function polynomial xxorder b5 yyorder 5 yxorder 5 xyorder 5 xxterms full yxterms full maxiter 100 reject 3 0 update yes pixsyst logical It is desirable to execute the task in interactive mode With this feature activated you can pick the outliers of the initial fit e g encircled plus marks in figure below and find a satisfying solution clicking on f key Page 118 of 148 Date January 1 2014 USER MANUAL 0 Figure 9 2 Example of the IRAF task ccmap solution The commands a
140. or not File archive number ASG declination DD PP SS oo right HH MM SS ascension Azimuth at start of degrees observation BIAS section Pixels Number of bits for data pixel Nee Default scaling N A factor Offset data range to that of unsigned N A short Additional Description AGI ARM Z90 means the ARM is placed at the center of the focal plane AGIFOCUS 0 is the correct value at center of focal plane Guide probe turn table position AIRMASS 1 means observation was started at zenith Name of the amplifier used during readout Amplifier section in pixels Boolean File archive number Useful to know which guide star was used during observation Useful to know which guide star was used during observation Telescope azimuth Bias section Area where to measure bias This means CCD 65563 ADU saturates at Scale factor applied to data values Offset applied to data values to avoid negative numbers 106 of 148 January 1 2014 USER MANUAL 0 9 7 f 2 First horizontal bin Indicates whether signal from CCDSUM 22 or more pixels have been summed i Pixels CCDSEC 1 2048 1 4102 CCD Section Area of the ccd actually read out unbinned Pixels T CCDSIZE 1 2048 1 4102 CCDSize Size of ccd in pixels unbinned CDI 1 6 1523E 05 WCS matrix World coordinate system matrix element 1 1 element 1 1 CDI 2 3 47495198 05 WCS matrix World coordinate syste
141. over half the number of the detector lines 0 1 s plus the readout time of this area In standard readout mode 200 kHz this time will be 8 25 s which can be decreased to 4 3 s using 500 kHz readout mode However using this higher readout speed is a non standard operation mode in OSIRIS and its performance is not guaranteed Figure 5 2 Example image taken through the frame transfer mask showing half the field blocked Frame transfer standard mode means using the same broad band Sloan or medium band SHARDs filter throughout the observation or a tunable filter adjusted to a fixed wavelength as no delays due to filters exchanging or TF tuning are possible since the shutter remains opened The difference of this mode with respect to the fast photometry 1s that the Page 70 of 148 USER MANUAL 0 Date January 1 2014 sampling interval between exposures is smaller since it 15 possible to expose while reading out obtaining a continuous series of temporal data A possibility for decreasing the minimum exposure time 15 to use a single readout window In this case the minimum exposure time will be determined by the size of the window combined with the readout time and the time used for skipping the remaining pixels This is independent on the window placement hence by knowing the desired window size and the readout speed the final minimum exposure time can be determined The following Table shows an estimates of the minimum
142. over the full field of view of OSIRIS Note that those coordinates are binned coordinates that 15 the standard operation mode of OSIRIS When 1 x 1 binning is used those values have to be doubled Page 35 of 148 Date January 1 2014 USER MANUAL 0 Figure 3 9 Image with OSIRIS tuned at 732 5 nm showing the 4 arcmin radius where no contamination from other interference orders is assured This is the operative FOV of the OSIRIS RTF The position of the objects in the Tunable Filter observing mode depends on the requirements of the PI since the value of the wavelength changes with the object s position in the FOV The PI must indicate in the Phase 2 form the coordinates to which the telescope will be pointing and the CCD pixel position corresponding to these coordinates By default the pointing will be done at 15 arcsecs from the optical center of the system in the pixel 50 976 at the CCD2 3 3 OSIRIS Tunable Filter available widths When working with the OSIRIS tunable filters the user needs to take into account two parameters the observing wavelength and the required FWHM The range of operation of the OSIRIS Blue Tunable Filter is from 450 nm to 671 nm while for the OSIRIS Red Tunable Filter the only available at the telescope is from 651 nm to 934 5 nm both ranges will be increased in future upgrades of the instrument It should also be noted that the practical use of the Tunable Filters 15 more res
143. pening the instrument for changing filters or masks shortly before Observations See environmental conditions in user manual Page 43 of 148 USER MANUAL 0 Date January 1 2014 Z vs RMA niii e A g La a p P d d Ls gt y 30 200 180 160 140 120 100 80 60 40 20 20 40 60 80 100 120 140 160 180 200 rotator anale dearees Figure 3 15 Variation of the TF tuning Z with the rotator angle All those factors produce day to day variations in the TFs calibration For this reason the TFs have to be calibrated before every observing block 3 5 Checking the calibration by using night sky emission lines The OH group produce relatively strong emission lines specially redwards of 700nm These are a nuisance in broad band and narrow band imaging as they are for long slit spectroscopy However they happens at precise wavelengths and with definite relative intensities and can be used for calibrating spectra or as in this case the tunable filter Since the FOV is fully illuminated by these emission lines rings are produced Knowing the wavelength of the emission line the radius of the ring that can be obtained using ds9 the tuned central wavelength can be derived As rule of thumb for a wavelength drift lower than 0 1 the variation Ar of the ring radius r should be in the worst case BT lt 0 02 3 21 r Page 44 of 14
144. project by going to File Configuration Config Obs Select the standard MOS mode no filter select the grism you want to use and set binning to the standard 2x2 pixels binning 1 1 is not accepted In the observation details box you select below the question Use Pre imaging the option Don t use it catalog Fill in the correct RA DEC and orientation that must correspond with the center of the OSIRIS field of view i e corresponding to the center of the mask An orientation angle of zero degrees will imply that North is at the top and East is towards the left of the Sky Editor and the Detector Editor views Although the MaskDesigner tool allows for the design at any orientation GRANTECAN only accepts mask that are either oriented N S or E W Our advice 15 that for fields to be observed close to the meridian without being affected by the dome shutter limitation vignetting for elevations above 72 degrees the slits are best oriented in the North South direction However fields that pass close to the zenith and will be affected by the dome shutter 1 9 declinations between approximately 10 and 47 degrees the slit orientation is best placed East West so that the field can be observed with the same mask both when the field 1s rising and when it is setting since the slits will remain reasonably close to the parallactic angle In the Box labeled Date System fill in the optimal date and hour angle for the observation These details ar
145. r the OSIRIS TF the main difficulty 15 achieving a relatively constant reflectivity for a wide spectral range from 370 to 670nm for the blue TF and from 650 through 1000nm for the red TF This implies multilayered coatings 1 thick coatings Then the minimum distance widest FWHM between plates is driven by the minimum distances between the coating surfaces not the plate surfaces Page 31 of 148 USER MANUAL 0 Date January 1 2014 ET100 OSIRIS Red 94 2 8 620 1000nm ET100 OSIRIS 91 3 390 670nm transmission transmission 375 425 475 525 575 625 675 600 950 1000 Wavelength nm bos nm Figure 3 6 Mean transmissions T for the blue left and red right OSIRIS TF The mean reflectivity R 100 T with a very good approximation This results in a mean R 91 for the blue TF and 94 for the red TF The wavelength dependence of the reflectivity R translates into a wavelength dependence of the FWHM range Also please note that the R 1s well behaved above 425 nm for the blue TF and above 650 nm for the red TF Hence deviations are expected at lower wavelengths 3 2 OSIRIS FOV for Tunable Filter Imaging OSIRIS TF provides a circular FOV of 4 arcmin radius where is assured that the observations will not have any contamination of other interference orders in the filter The TF as any interference filter changes its response with the incident angle 0 according
146. rdinates first the two CCD images must be combined into a single frame where the pixel coordinates are continous and geometrically correct by creating an image mosaic This is accomplished using an IRAF task mosaic V5 2x2 wbBiasRed wcsup cl that has been written for this purpose and that 15 made available on the GTC web site It is used in the following way Place the script mosaic V5 2x2 wBiasRed wcsup cl into your data directory Then open IRAF and go to the data directory Load the task into IRAF by typing the following at the IRAF prompt task mosaic mosaic V5 2x2 wBiasRed wcsup cl e Run the task on your raw image by typing at the IRAF prompt mosaic 12345 fits where of course the FITS file name must indicate the filename of the input OSIRIS image The output file 15 called OsirisMosaic fits and has a single layer containing the image of both CCDs This is the FITS file you will be using to determine pixel coordinates of your targets You can rename this file to anything you like Page 98 of 148 USER MANUAL 0 Date January 1 2014 From this mosaic FITS image use IRAF or any other tool to identify your targets and measure the targets centroid positions for instance using the IRAF imexam routine with option r As an alternative one can use the MaskDesigner tool itself to directly identify targets This is described further down However the preferred and most secure method 15 what is described here Place
147. re the image 15 read out For shuffled TF imaging an aperture mask ensures that only a section of the CCD frame is exposed at a time For each exposure the tunable filter is systematically moved to different gap spacings in a process called frequency switching This way a region of sky can be captured at several different wavelengths on a single image Alternatively the TF can be kept at fixed frequency and charge shuffling performed to produce timeseries exposures The TF plates can be switched anywhere over the physical range at rates in excess of 100 Hz although in most applications these rates rarely exceed 0 1 Hz If a shutter is used this limits the switching rate to about 1 Hz Charge on OSIRIS CCDs can be moved over the full area at rates of 30 50 Ls line it is only when the charge is read out through the amplifiers that this rate is greatly slowed down to the selected readout speed The high cosmetic quality of OSIRIS CCD allows moving charge up and down many times before significant signal degradation occurs In this way it 15 possible to form discrete Images taken at different frequencies where each area of the detector may have been shuffled into view many times to average out temporal effects in the atmosphere 3 1 3 Order sorters A FabryPerot Filter clearly gives a periodic series of narrow passbands To use a FPF with a single passband it is necessary to suppress the transmission from all the other bands that are potentially det
148. rge transfer shaffling mode Sequence total number of images in frame transfer mode Page 112 of 148 USER MANUAL 0 NUM_INDX NUM_ROIS NUM_SHIF OBJECT OBSCLASS OBSERVAT OBSERVER OBSMODE OBSTYPE OPENTIME OPTCENTX OPTCENTY ORIGFILE ORIGIN NGC1234 Science ORM SA OsirisDark Calib 12 23 T 7 595 1000 1001 Jan14_050116 fits GRANTECAN Date January 1 2014 Image Index into sequence Starts Integer from 0 Number of integer windows Number of times Integer charges are moved 56 OSIRIS comment N A Observation class N A Observatory name N A Observer Name N A Observation Mode N A Observation Type N A Open Shutter Time HH MM SS OSIRIS Optical Center X OSIRIS Optical Center Y Filename N A Organization responsible for N A creating the FITS Image Index within sequencein in frame transfer mode Starts from 0 Number of CCD windows maximum 5 Number of times charges are moved in charge transfer shaffling mode Should be the user defined target name This should be the observation class like SCIENCE Or CALIBRATION Duplication of OBSTYPE name of the Roque de los Perhaps the observatory Muchachos Observer name SA support astronomer Instrument observing mode for data factory use Observation type should be either SCIENCE or CALIB Time the OSIRIS s
149. roperties of a specific slitlet can simply be accomplished by changing any of the input boxes First select a slitlet in the list so that its properties will show up and can be edited For instance the pixel coordinates may be altered the slitlet might be given an angle its size changed or the wavelength range of interest adapted Slitlets may also be deleted from the list by activating the Delete Slit button Or the priority of a slit may be altered so that it is given the approriate weight when the MD tool optimizes the mask design Page 100 of 148 USER MANUAL 0 Date January 1 2014 Priorities of slitlets are treated by the MD program in the following fashion in case of conflict between slitlets the slit with the lowest number remains in the primary mask design while slits with a high priority index are automatically translated to a secondary mask When you are done with your design just save the Mask Design Project file by selecting File Save MDP and giving it an appropriate file name At a later stage you can reload this file and continue work where you left off It is important to note that since the pre image design essentially deals with translating detector pixel coordinates to mask coordiantes no account is made for atmospheric refraction Nor is proper motion of the objects accounted for the image is assumed to correctly represent the actual sky 7 6 4 2 Example 2 Using equatorial coordinates This s
150. roviding a listing of all the slitlets that have been defined 3 Buttons for some specific actions 4 Tick boxes to select visualization options for the slit geometry 5 Lasting of the details of the slit size and orientations in three different coordinate systems equatorial pixel and physical coordinates 6 Boxto set slit properties 7 Boxto define target details Page 93 of 148 USER MANUAL 0 Date January 1 2014 280350preimageSlits mdp MaskDesigner v3 24 File Manufacturing Dev Configuration Options Window Info Target Type Priority Valid Fiducial I unnamed 13854722294 C 0 Ok Yes 6 unnamed 13854722564 D Ok Yes unnamed 13854722724 Ok Yes 8 unnamed 13854722964 D Ok Yes 9 unnamed 13854723340 2 Qk Yes 6 10 unnamed 13854723838 C 0 Dk Yes 239 4803 11 unnamed 13854724103 C D Ok Yes y 12 unnamed 13854724941 R 0 Ok i 466 2085 13 unnamed 1385472623 8 R D Radius arcsecs 2 Delete Slit Detector Editor Masks Preview Geoms Activation E EE I I ous I B slitinTime 0 SkyEditor Mask Editor 3 Offset Viewer Extra v Fiducia RE Spectra Range min nm 550 max mmn 600 unnamed 1385472229460 Sky Mask Detector F Bounds Bounds Bounds b Target tgt gt slit slit gt tgt 102 8029 xPix 239 4803 m Name DEC 41 4735 yPix 466 2085 unnamed 1588972228
151. s VPHs covering low to intermediate resolutions from R 300 up to R 2500 The following table summarises the resolutions and spectral ranges available For the end to end efficiencies including telescope instrument and detector the measured transmissions measured so far are in Section 11 Resolutions and dispersions are measured at X4 A for a slit with of 0 6 Dispersions correspond to binned pixels that 15 the standard operation mode while the physical pixels unbinned dispersions are half of those listed in the table Rl aai ln cd el ue w E SE For R higher than 1000 the spectral range covered is limited by detector size Lower resolutions are limited by second order light Red optimized dispersers require the use of an order sorter filter GR see Figure 6 1 to suppress the second order light Page 72 of 148 USER MANUAL 0 Date January 1 2014 Filtro Centro 100 an 50 40 Transmission 3 30 20 0 450 500 550 Bn Wavelength nm Figure 6 1 Measured central spectral response of spectroscopic OS The spectral direction in OSIRIS coincides with the vertical direction on the detector hence spectra are not affected by the gap between both CCDs 6 1 Acquisition in Long Slit Spectroscopic mode In long slit spectroscopy mode point sources are centered on the slit at the coordin
152. ses On the fly observations enabled For ex Galaxy clusters Drilling masks overheads TF pre imaging avoid IFU mosaic Page 46 of 148 USER MANUAL 0 Date January 1 2014 i Trade off Y w Y 7 Position N lt know N Y i gt LS MOS or IFU LS or MOS Y classical case 2 or 2 objects targets Figure 3 17 Tree for deciding the most appropriate mode TF versus spectroscopy Av is the line width or velocity dispersion the target diameter p the density of targets and AFlux the error flux required lt gt O lt LLI m lt lt oO O LL t O 3 6 2 Observing Strategies The observing strategies for a TF are driven by the following instrumental effects 1 The spectral response of the TF more peaked and with more wings than a Gaussian or a squared 5 layer interference filter Figure 3 5 2 The diametric ghosts 3 The centre to edge wavelength variation and affects the way to design an observation depending on the characteristics of the sources e Photometric accuracy requested Please note that from now on we will refer to photometric accuracy of instrumental origin not due to readout or photon noise e Possible neighbouring lines to the one studied e Velocity field or line width of the target Page 47 of 148 USER MANUAL 0 Date January 1 2014 e Size of the target e Redshift of the targ
153. set Normally circular apertures are used for the fiducial alignment stars in the field and hence the tickbox fiducial should be activated The minimum radius for fiducial holes is 2 arcsec Just close the window after having edited your default values All the slits that will be defined now will take as default values of the parameters that you last selected When you are interactively defining slitlets to change for instance from defining fiducial holes to rectangular slitlets you need to go back to the configuration panel and change the default to rectangular with the appropriate sizes When having configured the setup it 1s advised to save the project by selecting File Save MDP and giving it an appropriate file name Now it s time to load the list of coordinates by selecting File Import targets and selecting the file you prepared If the software has accepted your file you should see your list of slitlets appear in the table in the MaskDesigner window The list will show which slitlets refer to fiducial objects or normal targets and whether the MD software encounters any problems with the design see the column labeled valid The slitlets that are not considered valid will require further attention Typical problems that are encountered are overlapping spectra with other slitlets that the slitlet falls outside the mask or that its spectral range falls outside the detector The design can be tuned in order to reduce the conflicts
154. ss talk effect between both CCDs in OSIRIS has been measured during instrument commissioning tests The effect is as small as 2 8 x 10 respect to the original signal hence the effect in the scientific images can be neglected SPEED 200 kHz 9 5 CCD1 l 1 L l l 1 l L l l lt ADUs gt l 10 15 20 25 30 35 40 45 50 55 60 65 t s 0 5 70 75 80 60000 50000 40000 30000 20000 10000 SPEED 200 kHz 9 5 CCD2 T T T T T T T T T T zT l 15 20 25 30 35 40 45 50 5 60 6 70 75 t s Fig 1 5 Linearity plots for OSIRIS standard readout mode in both CCDs Cosmic ray events have been measured in both OSIRIS CCDs resulting an average of 30 impacts min that means around 1800 impacts h 1 2 4 Quantum Efficiency The detectors are optimized for longer wavelengths but with a low although reasonable blue efficiency of about 20 3 365nm Hence observing at these wavelengths 15 possible although slow OSIRIS CCD QE 100 90 80 L 70 5 60 o ij 90 E 40 gt G 30 20 10 0 300 400 500 600 700 800 900 1000 wavelength nm Figure 1 6 QE of OSIRIS CCDs Page 16 of 148 USER MANUAL 0 Date January 1 2014 1 2 6 CCD windowing OSIRIS CCDs allows to define up to 5 windows at the same time for SIMPLE readout modes and only a single window for FAST MODES There are some restrictions that the user has to take into account when def
155. ssociated to the Interactive option and further details are given in the task s help If update parameter is turned to yes the task appends the parameters of the astrometric solution here named image db to the image header A tnx projection is highly recommended As additional output the file image res contains a line for each astrometric object with the following structure Column 1 X pixels Column 2 Y pixels Column 3 Ra Longitude degrees Column 4 Dec Latitude degrees Column 5 Fitted Ra Longitude degrees Column 6 Fitted Dec Latitude degrees Column 7 Residual Ra Longitude arcseconds Column 8 Residual Dec Latitude arcseconds 9 2 3 Mosaic Composition To optionally create a mosaic in WCS from individually corrected frames use first the mscimage task of the mscred package This task puts in a common system both WCS referenced frames of any scientific image Input images are the exposures to be resampled into a single image and the output must match the number of input images Use a minimum of 30 grid points nx ny over the input image to determine the mapping function Also the parameters fitgeometry function x y orders and x y terms should match Page 119 of 148 USER MANUAL 0 Date January 1 2014 those previously selected In the ccmap task Once both frames are In a common reference system you can combine both frames to obtain a single Image using the task imcombine setting b
156. stronger at CCD1 than in CCD2 f687w17 amp 80 8w17 1 1 00 amp 90 1w16 7 1 00 BB7 9w17 5 0 97 amp B7 1w15 B 0 98 684 3w186 5 0 89 5681 3w16 6 0 84 amp B0 6w11 7 0 79 B78 3w16 9 0 75 Transmission Figure 4 3 Left Change in the Sky lines coverage with SHARD filter U687 17 as the central wavelength moves bluewards along the OSIRIS FOV Right Sky image with the same filter showing the radial differences in background level from both CCDs This effect can be clearly also seen in Figure 4 3 right where a sky image with U687 17 filter is shown Note the strong gradient observed in the background level and how this follows a radial geometry from CCD1 to CCD2 This effect should be taken into account when using the sky flat frames that can show some variability as sky emission itself changes in any case this can be properly corrected during the data reduction process As it is shown the sky background correction plays a very important role in the data reduction for observations obtained with SHARDS filters In order to have initial estimates of the background levels with SHARDS filters average values for the sky background counts are shown in the previous Table For a detailed description on the full characteristics of the SHARDS filters as well as complete details on the calibration process data reduction etc see Per z Gonzalez et al 2013 Page 67 of 148 USER MANUAL 0 Date Januar
157. the Mask Designer tool To start the design begin with opening a new project by selecting from the File New MDP Setup the global parameters for the project by going to File Configuration Config Obs Select the standard MOS mode no filter select the grism you want to use and set binning to the standard 2x2 pixels binning 1 1 is not accepted In the observation details box you select below the question Use Pre imaging the option Use a pre image file and you identify the FITS file that must contain the moasic image that you prepared earlier Ignore the Telescope Offset boxes When you re done select Commit changes and save the MDP file Next step is to set up the default slits and fiducial star holes For that go to File Configuration Config Default Slits where you can proceed to define rectangular slits circular holes used for the fiducial alignment stars and curved slit Note that curved slits are not yet supported For the rectangular holes you can specify the generic size as well as the typical wavelength range of interest and their generic orientation Note that in case the field orientation 1s set at 0 degrees then the slit angle would normally be set at 90 degrees Page 99 of 148 USER MANUAL 0 Date January 1 2014 These geometric details can later be tuned per slitlet if necessary The minimum supported slit width 15 1 2 arcsec Similarly for circular apertures the diameter can be
158. the scientific program use another slit a possible small drift in the lines could be observed due to the different position of the slit in the OSIRIS focal plane To use the master arc it is necessary to correct for a possible drift in the lines by correlating the short exposure lamp frame with the master frame For OSIRIS low resolution grisms R 300 500 and 1000 there are also individual arc line maps available for each of the calibration lamps used that are shown in Section 12 Note that in the HgAr lamp there are a series of high excited Argon lines that appear only during the first few seconds of the exposure Those usually are not provided when calibrating the scientific data but in case that they contribute noticeably in the final HgAr arc image an additional Ar line map has been also produced for each grism Page 76 of 148 en gt lt Z lt gt 24 un Date January 1 2014 lamps ion HgAr Xe Ne calibrat OSIRIS R300B 9 6 66 19 02 6626 9 9 2916 lexcrcyro6 252 Z968 19X 6488 9 095 5678 IN 8091158 lex S 9 1 78 86 022 11 901 6 97 I9N 668 8 Y47 IN 2975905 N 9F6 EZI T C 0Z I9N 2976269 I9N r0 2 49 I9N 92782799 aN 66 BAGG ISN 228 2ES9 82S 9059 t6S 919 I9N 90 v 1 9 19457 9929 ION TES S466 YES FY6S
159. the wavelength range of interest that the MD will use to detect any conflicts This information can be set in the section labeled Spectral Range If a same limited range 15 to be used for all slitlets it is recommended to first set these default values for the whole project in the Default slit configuration window before importing coordinates or otherwise defining slitlets 7 6 4 Designing MOS masks step by step There are two distinct starting points when designing and OSIRIS MOS mask 1 using target coordinates based on pixels of an OSIRIS r band image or ii using target coordinates based on equatorial J2000 coordinates The two options have a distinct treatment and are therefore described separately following specific examples 7 6 4 1 Example 1 Using an OSIRIS pre image Using an image taken with OSIRIS as the basis for designing a mask is the easiest and hence preferred method to successfully obtain multiple object spectra with OSIRIS This so called pre imaging mode requires you to have access of an OSIRIS image of the field taken in the Sloan r filter and on which your targets can be identified This image must have exactly the same position and orientation as will be used for the spectroscopic observations this is essential since the field distortions for OSIRIS are significant and non symmetric An OSIRIS image consists of a mosaic of two CCDs with a gap and a slight shift and rotation between them In order to measure pixel coo
160. to deviations from flat parallel plates The exact details depend on the type of deviations Atherton et al 1981 A FPF manufactured with V 80 and a reflection coefficient of 0 97 N 100 performs with a finesse of about 60 The aperture finesse N A 3 13 where Q is the solid angle of the cone of rays passing through the FPF This equation is related to the 2 dependence on in Equation 3 2 In terms of astronomical imaging the effect of aperture finesse is negligible for most objects in the field of view of a telescope For example an object which is one degree across in the collimated beam imaged with m 50 has N 500 according to Equation 3 13 A more relevant analysis to consider the change in central wavelength of the filter as the ray angle 15 varied in Equation 3 2 For example a change in ray angle from 1 to 3 produces a change of 0 146 in the central wavelength of the filter at any given order Therefore at high resolving powers 1000 a FPF may not be truly monochromatic across a desired field of view 3 1 1 3 Gap scanning etalons In order to manufacture a tunable FPF which can change the central wavelength for a given order it is necessary to be able to adjust either the refractive index of the cavityz the plate separation d or the angle as can clearly be seen from Equation 3 2 In a gap scanning etalon the plate separation can be controlled to extremely high accuracy Page 27 of 148 USER
161. to the formula LN 3 15 where is the central wavelength for normal incidence Ag for the incident angle and n the refraction index As a consequence for filters in a collimated beam OSIRIS case beams from different points of the GTC focal plane reach the TF at increasing incident angles with symmetry with respect to the optical centre Then there is a progressively increasing shift to the blue of the central wavelength as the distances r to the optical centre increase according to Eq 3 15 However since the beams coming from the same point of the FOV are parallel the FWHM is nearly the same This is the case of OSIRIS since OSIRIS TF are located in the pupil of the collimated beam Since this is a pure geometric effect the wavelength variation 15 completely fixed and predictable because it depends only on the incident angle that is completely determined by the ratio between the telescope ferc and the instrument collimator mirror fcon focal lengths tan r 136 91tan r 3 16 Page 32 of 148 USER MANUAL 0 Date January 1 2014 since the measured focal lengths are forc 169888 2mm Castro et al 2007 and fcon 1240 90 0 05mm SESO 2006 The distance r to the OSIRIS TF optical centre can be obtained from the OSIRIS mean plate scale of 0 127 arcsec pixel Wavelength or temperature variations can be neglected since the OSIRIS collimator is made of Zerodur and the camera has demonstrated to be ver
162. tools documentation jsky html The MD tool runs locally on your machine and hence needs to be installed You need to have the JAVA Runtime Environment Version 1 5 0 or later installed see http java com en download index jsp First download the latest version from the GTC web site see the OSIRIS instrument pages for the most recent location Then unpack the compressed file by typing unzip MDv325 zip the filename may be different depending on the version Within the directory structure you will find the Java program MaskDesigner jar that you can start by typing the command gt java jar Xmx256m or simply just double clicking on the file in your directory might start the program To force the use of the latest version of java in a typical linux platform one may type gt usr java latest bin java jar Xmx256m MaskDesigner jar If you wish to start up the MaskDesigner software directly loading a specific mask design file one may pass that file at startup as given in the following example gt java jar Xmx256m MaskDesigner jar projects abell 2065 test mdp 7 6 2 Getting to know the Mask Designer Before starting work with the MaskDesigner MD it is useful to understand some basic principles of its function The main goal of the MD 15 to provide an interface and conversion between either the equatorial sky coordinate system RA DEC in J2000 or the OSIRIS detector pixel coordinat
163. trast greater than 100 the reflection coefficient R of the coatings needs to be greater than or about 0 82 The wavelenght spacing between passbands known as the inter order spacing or free spectral range FSR is about AA 3 5 A m which is obtained from Equation 3 2 by setting consecutive integral values of m Each passband has a bandwidth 6A full width at halfpeak transmission given by A 1 R oA mzR 2 r 3 6 derived from Equation 3 1 The ratio of inter order spacing to bandwidth is called the finesse A N AA 3 7 on 2 T r min For an ideal it is given by A R N d 22 3 9 1 R Thus we see that resolving power of 15 equal to product of order the finesse 3 10 Page 25 of 148 Date January 1 2014 USER MANUAL 0 AR alr glass glass alr O s Figure 3 1 Schematic diagram of interference with a FabryPerot filter The outside surfaces of the glass are coated with antireflective AR coatings while the inside surfaces are highly reflective usually gt 0 8 The air cavity in the middle is not shown to scale usually d is about 10 whereas the glass is over 20 mm thick on both sides At resonant wavelengths the first reflection shown with a solid line interferes destructively with light coming from the cavity in the same direction
164. tric accuracy is determined by the time needed for the vertical displacement of the charge on the CCD typically by 50 us row For example to displace 12 binned pixels requires 0 0012 s this will be the minimum exposure time allowed in this configuration hence for exposure times larger than 0 1 s the photometric accuracy will be better than 1 For larger pixel shifts the minimum exposure times required will increase accordingly Standard configurations for this mode allows obtaining up to 147 consecutive images before readout see Figure below as an example However more conservative numbers are recomended 70 90 consecutive images per frame in order to avoid possible flux contamination from the previous images along the series The fast photometry standard mode means using the same broad band Sloan or medium band SHARDs filter throughout the observation or a tunable filter adjusted to a fixed wavelength as no delays due to filters exchanging or TF tuning are possible as this is a shutterless mode I Figure 5 1 Example image taken in fast readout mode where many individual narrow strip images are combined in a single detector readout The only delay in the series would be imposed by the readout time once the detector 1s filled with the individual images plus the 4 s delay needed for clearing configuring the detector In standard readout mode 200kHz this time will be 2
165. trictive than was originally anticipated For the Red Tunable Filter RTF the minimum achievable width that is imposed by the design of the order sorting filters in order to avoid contamination by other interference orders within the FOV is 1 2 nm for most wavelengths except for the longest wavelengths where even narrower pass bands can be tuned There 15 Note that those coordinates are binned coordinates that 15 the standard operation mode of OSIRIS When 1 x 1 binning is used those values have to be doubled Page 36 of 148 USER MANUAL 0 Date January 1 2014 also a maximum width depending on the wavelength range Next Table shows a summary of the avaliable FWHM ranges when using the RTF RTF range nm RTF available FWHMs nm 651 0 lt lt 800 0 1 2 lt AX lt 2 0 800 0 820 0 1 0 lt AX lt 1 5 820 0 lt lt 840 0 0 9 lt A lt 1 4 640 0 lt lt 880 0 0 8 lt AX lt 1 3 880 0 lt lt 910 0 0 85 lt A lt 1 2 910 0 lt lt 934 5 0 9 lt AX lt 1 2 In addition to the Information of the maximum tunable widths with the TFs as a function of wavelength see table above Figure 3 10 shows the available range of widths as a function of wavelength The minimum width is 1 2 nm for most wavelengths to avoid contamination due to other orders in a circular FOV of 4 arcmin radius For the longest wavelengths gt 800 0 nm even narrower pass bands can be tuned thanks to an upgrad
166. ure time OSIRIS limiting magnitudes imaging mode Sloan g Sloan r Sloan i iii O si m aan unn E 3 111199 att t nint 1151 augers prd iamdiu H inniti umi nins H unti nii in n purus magnitude S N 0 1 2 3 4 5 6 7 A exposure time h OSIRIS limiting magnitudes imaging mode Zo ef 26 5 26 3 1 puit 29 9 w motui uiu i nu minii mnn f nuu ww eins ant imn apnd magnitude S N an adi 23 5 23 22 5 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 exposure time h Figure 2 5 Limiting maenttudes S N 3 achieved with OSIRIS broad band filters as a function of the exposure time assuming dark conditions seeing 1 0 arcsec and airmass 1 2 A detailed view for exposure times lower than 1 0 h is shown in the graph below Page 22 of 148 USER MANUAL 0 Date January 1 2014 22 Photometric uniformity Given the structure and speed of OSIRIS shutter of type moving screen and that it is near collimated beam exposures down to 0 1 seconds can be obtained with a uniformity of about 1 over the full field 2 3 Sky Flat fields The flat fielding homogeneity In each of the OSIRIS Sloan filters is better than 2 5 over the full unvignetted FOV of the instrument except in Sloan u where fluctuations up to 6 with respect to the mea
167. velength calibration Z scans e Wavelength shifts The main consequences for the data are e Transmission losses e Wider FWHM and distorted spectral response Page 40 of 148 Date January 1 2014 USER MANUAL 0 The XY resolutions used for parallelism calibration 50 and 25 bits respectively have been chosen as the most convenient Larger steps are not accurate enough and the XY errors affect wavelength and transmission as shown in the following table approximate values to serve as example only for the red TF errors A shift T T Red TF nm 96 4 1 ET It is important to keep a good parallelism better than 50 bits in X and 25 in Y Again note that Y is more sensitive File Edit View Frame Zoom Scale Color Region WCS Analysis Help File Edit View Frame Zoom Scale Color Region WCS Analysis Help File Jan15_212324 fits CCD 2 L2 Object Value 1745 File Jan15_212835 fits CCD 2 L2 Object Value 179 x 57 000 Y 1315 000 Image x 107 000 Y 1315 000 Frame 1 Zoom 0 125 Angle 0 000 Physical x 41 000 Y 1259 000 Image x 91 000 1259 000 Frame 1 Zoom 0 125 Angle 0 000 file edit view frame zoom scale color region wes help x wuwumw b 3 lt 2 gt x uu FYB e file edit view frame zoom Scale color region wes help linear log ower square root squared histogram min max zscale 8 54 8 5 2c 20 File Edt view Fram
168. way it is possible to achieve a very good continuum and sky subtraction with a direct pixel to pixel difference between your on line and your continuum image However TF have quite narrow FWHM and hence the exposure times are quite large 2 Using a medium band and OS or broad band filter Sloan SDSS In this case continuum subtraction is not as good and certainly not as direct and must be faced with caution Since the continuum filter 15 tens of times wider that TF the exposure times required are reduced accordingly Page 48 of 148 USER MANUAL 0 Date January 1 2014 If the TF 1s to be used for continuum subtraction the TF tuning of the off band has to be chosen so that no or few emission enter into the continuum filter This is driven by the photometric accuracy required via the following expression derived from Eq 3 14 1 H T uir 3 25 This equation can be interpreted in this case as providing the transmission 7 normalized to unity of your continuum filter tuned at 4 and of FWHM OA at the wavelength A of the on line tuning For example let assume that the continuum must be chosen with a contribution from the emission line lower that 5 Then for a given FWHM of say 1 8 nm the tuning of the continuum must be placed 4nm away from the line tuning Of course wider FWHM require increasing the wavelength difference between on and off line tunings Line Line ON band
169. when obtaining TF imaging of bright crowded or extended fields e Pinhole masks for Long Slit and Multi Object Spectroscopy tests Page 9 of 148 Date January 1 2014 USER MANUAL 0 Figure 1 3 From left to right charge shuffling mask selecting the central 1 3 of the detector lines the central black circular piece is shown just for reference frame transfer mask selecting the half of the detector exposed and the fast photometry mask with the decentred slit of 3 arcseconds width 113 Observing modes The following table provides a summary of the different OSIRIS observing modes that are described further on in this manual Mode Imaging ED SS ol o LLL Broad band Narrow band Single exposure Scan A set of exposures at several equidistant amp contiguous wavelengths Medium band SHARDS private filters set Spectroscopy www ss Long slit MOS Standard Fast photometry Page 10 of 148 USER MANUAL 0 Date January 1 2014 1 1 4 Characteristics The following table summarises the main instrument characteristics Figure 1 4 MOS FOV Image quality Kk 0 15 8096 polychromatic EE Instrument Position l1 50 540346 Angle Detector system Two MAT 4k x 2k 9 4 arcsec gap from same Si wafer Broad band eriz filter medium band TF order sorters OS and medium band SHARDS filters Central tunable from 450 through 935 nm FWHM tunable from 4 5 through 20
170. wo CCDs Output and no binning takes 31 seconds at 500 kHz readout speed and about 50 s at 200 kHz Page 14 of 148 USER MANUAL 0 Date January 1 2014 122 OSIRIS standard CCD operation modes As it was described in Section 1 2 1 the CCDs control system offers a wide range of readout modes and gain settings but for the time being the standard observing modes are shown in the table below In the scientific standard mode the detector linearity is guaranteed up to the full 16 bits signal maximum Read noise 1s better than 5 electrons in the standard readout mode used for both imaging and spectroscopy The acquisition mode is generally used for test images but not for science data This mode has a significant high noise pattern so it 15 not suitable for scientific cases The following table gives an overview of the main characteristics of the standard readout modes Imaging Spectroscopy Slow Acquisition Standard Readout CCD1 CCD2_ A CCDI CCD2 A CCD1 CCD2 A configuration Readout velocity 200 kHz 100 kHz 500 kHz Gain e ADU 0 95 1 15 1 46 Saturation ADUs 65 000 65 000 55 000 Binning X x Y 2x2 2x2 2x2 Readout time 21 sec 42 sec 7 8 sec Actual readout 4 5 e 3 5e 6 noise A frequent monitorizing of the Gain and Readout noise for the standard operation mode of OSIRIS 15 done for operational purposes and the values are updated at the OSIRIS site at GTC web page IMPORTANT In order to decrease the overheads during OS
171. xy or to get two nearby targets into one slitlet Curved slits however are not yet admitted As described before the instrument field orientation must be such that the general slit orientation is either North South or East West When designing masks based on OSIRIS images only images taken in the Sloan r band and with standard binning 2 x 2 may be used Users may consider doing MOS spectroscopy with a grism in combination with a medium band filter so that only a part of the spectrum will be shown In that way more objects can be packed into a single mask However for the moment this way of operation is not yet supported 7 4 Calibrating MOS observations Standard calibrations provided by the observatory for MOS data will be identical to those for normal spectroscopy i e including a spectro photometric standard star observed with the correct grism and a normal wide longslit Any special night time calibrations need to be defined in the phase 2 tool as observing blocks and the time will be charged to the observing program Accurate absolute flux calibration in MOS mode can be a difficult matter and must be planned with care For specific calibrations each PI will have to define observing block specifically for the purpose of calibrating her his science data 7 5 Designing MOS masks a summary Designing OSIRIS MOS masks is not a very complex process in itself thanks to the Mask Designer tool that helps the user in making the r
172. y 1 2014 2 BROAD BAND IMAGING OSIRIS allows broadband imaging over a FOV of 8 53 x 8 67 7 8 x 7 8 unvignetted covering the full spectral range from A 3650 to A 10000 with a high transmission coefficient in particular at longer wavelengths All standard OSIRIS filters have been designed to work in a collimated beam with a tilt angle of 10 5 to avoid ghosts due to back reflections into the detector The OSIRIS standard pointing in Broad Band imaging mode is at the CCD2 pixel 256 1024 to maximize the available FOV and in order to avoid possible cosmetic effects which are more abundant in the CCD1 The coordinates introduced by the PI in the Phase 2 tool will be positioned at this central pixel 2 1 1 Sloan broad band filters Broad band imaging with OSIRIS covers a spectral range from A 3650A to A 10000 using the standard Sloan filters u A3500 600 9 A4750 1400 1r 46250 1400 i 7700 1500 and z A9100 120 The following table provides the measured parameters at the IAC optical laboratory at ambient temperature at the centre of the filter and with normal incidence Due to JAC Laboratory limitations no measures for u filter are available aside from those provided by the manufacturer Central wavelength FWHM A A eee NM g 485 150 8148 The filters are placed in the collimated beam and close to the pupil of the instrument at an angle of 10 5 with respect to the optica
173. y 1 2014 4 1 Photon detection efficiency with SHARDS filters The graphs below shows the overall photon detection efficiency of GTC and OSIRIS with the SHARDs filter set and the overall system efficiency of OSIRIS in imaging mode as a function of wavelength Note that the curves for the tunable filter order sorters the efficiency of the tunable filter itself 1s not included in the curve OSIRIS SHARDs filters 0 45 T T T 0 4 0 35 Efficiency ho o Cn 0 2 0 15 0 1 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenqth A Figure 4 4 SHARDs filters efficiency curve OSIRIS imaging mode 0 45 5055 SHARDs OS RTF mimm 0 4 OS 1m 0 35 gt 03 C 0 25 0 2 0 15 0 1 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 wavelenath A Figure 4 5 Overall efficiency of OSIRIS in all the available imaging modes with medium and broad band filters Page 68 of 148 Date January 1 2014 USER MANUAL 0 5 FAST IMAGING MODES 5 1 Fast Photometry For fast photometry with OSIRIS a mask with a 7 x 3 slit is used the fast photometry mask This slit 1s placed in one of the detector edges The images are obtained while the shutter remains open and after each exposure the charge 15 shifted a number of lines at least the equivalent to the width of the slit 12 pix approximately in standard 2 x 2 binning mode The minimum exposure time and photome
174. y 1 2014 6 2 Flexure OSIRIS allows a very stable spectral calibration with no significant drifts with rotator position 1 pix thanks to its active collimator Therefore the calibrations for each observation can be taken at the beginning or at the end of the night regardless of the orientation of the instrument when the science observation 15 carried out Figure 6 2 shows an example of the wavelength shift as a function of rotator angle for two spectral resolutions 0 8 T 0 8 T T e e 0 6 0 6 e 04 0 4 0 2 0 2r X x g e ore e OF 9 gt 0 2 gt 02r e 0 4 0 4 e e 0 6 0 6 0 8 0 8 OSIRIS R1000R 180 120 60 0 60 rotator angle degree 120 180 OSIRIS R2000B 180 120 60 0 60 rotator angle degree 120 180 Figure 6 2 Shift in the spectral direction Y for the arcs emission lines with rotator position for OSIRIS R1000R left and R2000B right The more extreme variations are lower than 1 pix binned 6 3 Fringing The measured value of fringing in the OSIRIS CCD is lt 1 for lt 9000 A and 5 for gt 9300 A with a slightly increase to 7 at higher resolutions R 2500 so it is relevant only at higher wavelengths and in the range z in imaging mode Figure 6 3 shows an example of fringing vs wavelength obtained with OSIRIS R500R OSIRIS Fringing GRISM R500R c 9 s
175. y achromatic during commissioning However as already stated in Section 3 1 1 1 Equation 3 2 apply to ideal FPFs Really the full expression of Equation 3 2 is mA 2 d cos0 2L d cos O 3 17 This additional term in Equation 3 17 can be neglected when d gt gt d as 15 the case for high resolution FPs since d 15 of the order of hundreds of microns while d is of the order of microns but not in FPF where both are of the same order of magnitude The contribution 15 more severe when the coatings are thick in other words when the wavelength range covered is wide as is the case of most FPF and certainly of OSIRIS TFs Also the additional term depends on wavelength since both refractive index and coating thickness depend on wavelength and this dependence 15 non linear The effect can be noticed even for normal incidence 0 0 producing effective etalon gaps that are wider than expected and hence FWHMSs that are narrower than expected and that depend on wavelength This has been observed mainly in the OSIRIS Blue TF specially between 490 and 590nm The FWHMs can however be considered nearly constant within the whole OSIRIS TFs FOV For this reason the wavelength variation of a FPF across the FOV does not follow a pure geometrical dependence as that given by the combination of Equations 3 2 and 3 16 This effect was first reported by Veilleux et al 2010 for the TF of the Magellan Baade 6 5m telescope These authors dete

OSIRIS USER MANUAL - GTC - Instituto de Astrofísica de Canarias

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OSIRIS USER MANUAL - GTC - Instituto de Astrof&iacute;sica de Canarias

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OSIRIS USER MANUAL - GTC - Instituto de Astrofísica de Canarias