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WIYN High-Resolution Infrared Camera (WHIRC) User`s Guide

1. File name dark_100s 57 Observe E Automatic display J Overunte files observe name dark_100s exposure 1 00 type Dark number 4 H J KS co WHIRC Filters LOW AIR mer open BR_G _4500 BR_G FE Il 4500 FE Il eae PA B E Fowler 1 hu Fowler 4 Min Exposure secs 3 6 Figure 5 16 WHIRC MOP for illustration of an exposure setup in this case a series of four 100s dark frames WHIRC User s Manual Version 1 07 2009 May 28 28 b Select the detector readout mode by clicking either the Fowler 1 or Fowler 4 radio button The use of rolling reset and Digital Average 4 are now the default modes for observing so they are not explicitly noted on the MOP 1 Fowler 1 uses a single readout at the beginning and end of the integration This mode will be used for broadband imaging and bright targets where one 1s either background or source photon noise limited and saturation 1s a concern 11 Fowler 4 uses four readouts at the beginning and end of the integration This will reduce the read noise by approximately a factor of two at the cost of a fourfold increase in the minimum integration time This mode is useful for faint objects or narrowband filters where one may be read noise limited even with long integration times NOTE The counts in the image files from the Fowler 4 will need to be divided by 4 to normalize the signal levels before linearity correction c Select Exposure type dark flat object et
2. 1 Y Offset deg 1 Number of X Dithers Number of Y Dithers Shape Selector Number of X Dithers Number of Y Dithers 2 2 1 Shape Selector Grid Grid Has al 3 HE EE us X Dither Size arcsec Y Dither Size arcsec X Dither Size arcsec Y Dither Size arcsec 20 20 Wa 20 20 Dither Repeat1 Expose Repeat 1 Exposure time s Dither Repeat 0 Expose Repeat 1 Exposure time s 1 Figure 5 24 The WHOMP GUI setup for a standard star dither pattern No spaces in the Target Name are permitted 2 Below in Fig 5 25 1s an example of a script used to image the Glimpse Globular Cluster GLM GC This script has dithering on source with a sky offset to a blank region on sky which is dithered in the same manner The target dither pattern 1s repeated only once with a 2x2 box pattern and a 30 arcsec grid separation The offset sky position 1s 0 1 degree in X and 0 1 degree in Y RA and DEC direction since this is done in equatorial coordinates and a 2x2 20 arcsec grid box dither pattern is performed The observing script parameters are saved as a file called GLM GC setup2 obs in the home observer observing scripts subdirectory and can then be loaded into MOP with the Load Observing script function in the File pull down menu NOTE currently the RA and Dec loaded into the WHOMP are not used by the MOP in the scripts WHIRC User s Manual Version 1 07 2009 May 28 38 Mie Map Designer File Recipes View WHOMP
3. Figure 5 10 The SAOimage ds9 display window 7 Single click on the start PyRAF button to bring up a PyRAF shell window for analysis of the data iw pyraf Konsole Session Edit View Bookmarks Settings Help flat Brg off 133 fits flat J on 057 fits test 012 fits flat Brg off 134 fits flat J on 058 fits test 013 fits flat Brg off 135 fits flat J on 059 fits test_014 fits flat Brg off 136 fits flat J on 060 fits test 015 fits flat Brg off 137 fits flat J on 061 fits test 016 fits flat Brg off 138 fits flat_J_on_062 fits test 017 fits flat Brg off 139 fits flat J on 063 fits test_018 fits flat_Brg_off_140 fits flat_J_on_064 fits test_019 fits flat_Brg_off_141 fits flat_J_on_065 fits test_focus_001 fits flat_Brg_on_122 fits flat_J_on_066 fits test_focus_002 fits flat_Brg_on_123 fits flat Ks off 112 fits test focus 003 fits flat Brg on 124 fits flat Ks off 113 fits test focus 004 fits flat Brg on 125 fits flat Ks off 114 fits test focus 005 fits flat Brg on 126 fits flat Ks off 115 fits test focus 006 fits flat Brg on 127 fits flat Ks off 116 fits test_focus_007 fits flat_Brg_on_128 fits flat_Ks_off_117 fits test_focus_008 fits flat_Brg_on_129 fits flat_Ks_off_118 fits test_focus_009 fits flat_Brg_on_130 fits flat_Ks_off_119 fits test_focus_010 fits flat_Brg_on_131 fits flat_Ks_off_120 fits test_focus_011 fits flat feii off 152 fits flat Ks off 121 fits test FS28 012 fits flat feii off 153 fits flat Ks on 097 fits whirc bias log
4. 0 waiting 243 1 exp 242 pixelsllone 0 waiting 242 1 exp 2241 pixelsllone waiting 241 1 exp 2240 pixelsllone waiting 240 11 exp 2239 pixelesllone waiting 239 1 exp 238 pixelsDone 0 waiting 238 1 exp 2237 pixelsllone waiting 237 1 exp 2236 pixelsllone 1 waiting 236 5 socket got asyncieg Oki ppxStartExpt Exposure is done ID 2454725 966992 Reading aut Progress was NReads 90 Mon Sep 15 16 12 39 MST 2008 Mon Sep 15 16 12 42 MST 2008 Queueing data datac15 Sep_08 dark_Ss_049 fits for archiving o Figure 5 7 The MOP debug log window automatically loaded with the MOP c MOP status window Similar in appearance to the MOP debug this window logs filter motions and flags such as enabling disabling WTTM guided dithers Hay 28 13 27 54 3340 Hay 20 13 27 54 460 wa init complete eel Hay 28 1312754 ttuhircd AA init complete init complete commanding 41 null primer command init complete Hay 28 13 27 54 hire May 20 1312754 iiuhiro Running with real hardware t tt Please wait for WITA module to load WITH module loaded Ok AAA AAA AAA AAA AAA AAA AAA titititi AAA AAA AAA This is the MOP command line intended for engineering and debug use only Do not type anything here and do not exit this xterm just leave it in it s iconified state HH RARE RRA Figure 5 8 The
5. Hestart Daemon Figure 5 1 WHIRC Engineering GUI which is displayed on the OA monitor The four tabs are described in this and succeeding figures WHIRC User s Manual Version 1 07 2009 May 28 13 b The Filters tab shows the location of the filters and provides detailed information on the gaussmeter readings Homing and resetting commands can also be performed here NOTE As with all the windows on the OA screen this is for engineering level debugging and not to be used by the observer for changing filters The observer should use the MOP for all instrument operations Options Filters Temperature Contol Temperature Status WIYN Staff use Only Wheel 1 Wiwel 2 Oppa Opm H A Ai us Rr y Ann kmis KS y Br y w CO Fe IN 4300 kmis w Lowe Airglue Fu IM w Mel u Pa amp 4500 kunfs 7 Open w Pa 8 filler NANDE filler NAA A CWL An gem A CWL 15 um AAIA an AAA inna N FWHM 0 0 am FWHM 1000 0 mm clegrees 0 degrees 0 steps 0 steps 0 gauss 660 1 G gauss 822 1 G detent ENE detent ENE status ok atahis ok aku error ok fw error ok Hernan Hi new Hesel Heart Veh ae a EA O SSS SSS SSS SS ee Heset Gaussmeter opposite filter opens Figure 5 2 Display of the Filters tab on the WHIRC Engineering GUI WHIRC User s Manual Version 1 07 2009 May 28 14 c Temperature control panel used for controlling the warmup and cooldow
6. K temp errar UVU UVA fK Coammands z Parameters Reset P roportional l we Haatar Off nleyral iterential Cool Uewn Set Polnt Goal K Warm Up Toles ance itate k min Figure 5 3 Display of the Temperature Control tab on the WHIRC Engineering GUI WHIRC User s Manual Version 1 07 2009 May 28 15 d Temperature status shows temporal plots of temperature for the various temperature sensors installed in WHIRC One can select plot parameters including which sensor temperatures to plot sampling period and temperature window This temperature status window 1s particularly important for monitoring the warmup and cooldown procedures RR OPA EA Fillers Temperabare Control Teanpershee Slulus PF be WIYN Staffuse Only o nas Temperature Status i Fags OR 1R SR AN Seg 2K 17 IRON Seg RATAN OM Siege OR 17 4K AN 4 2 Temperature K SEA sand Tarn secumds a eS Mut Chements Temp Range amity Prol Witt 1 huur Semple Periud 10 vecumds M track end Figure 5 4 Display of the Temperature Status tab on the WHIRC Engineering GUI WHIRC User s Manual Version 1 07 2009 May 28 16 4 Single click on the start Pan button This opens a VNC session to the whirc pan computer which is displayed on the observer monitor as a 4 panel status window After a successful initialization the window may be minimized with the button to red
7. Version 1 6 30 Nov 2007 Target Name IGLM GO AA Target Coordinates Heliocentric Equatorial Coordinates h Equatorial Right Ascension aay H a M 0 000 S 9 Ecliptic Declination 0 D 0o 0000 v Galactic Rol op o f 0000 Equinox 2000 Map Designer Number of X Cells Number of Y Cells Shape Selector 1 1 Grid _ LJ w Plus X Cell Spacing arcsec Y Cell Spacing arcsec 180 180 A A A AAA Map Repeat 1 Sky Dither Designer Map Dither Designer X Offset deg 1 Y Offset deg A Number of X Dithers Number of Y Dithers Shape Selector Number of X Dithers Number of Y Dithers a Shape Selector 2 3 Grid Grid 2 us w Plus X Dither Size arcsec Y Dither Size arcsec X Dither Size arcsec Y Dither Size arcsec 30 30 mee 20 20 BEE Bas jon ud paa Dither Repeat 1 Expose Repeat 1 Exposure time Ss 20 Dither Repeat 0 Expose Repeat 1 Exposure time s wy Xx vi Map Designer File Recipes View WHOMP Version 1 6 30 Nov 2007 Target Name GLM GC Target Coordinates Heliocentric Equatorial Coordinates 9 Ecliptic Declination s Saye as w Galactic Roll E cobbKs obs hga_tes ex2grid_20arcsec ohs E darks obs hga_tes Number of X Cells 2x2grid_50arcsec obs focusseg obs hga_tes Shape Selector 2x2grid_75arcsec obs fs29 obs hga_tes Grid bethany_J_band obs E GLM_CL obs hga_tes bethany_K_band obs E GLM GC tel K_files t bethany_K_band obs E hga_testobs obs Map
8. time of 4 s this yields a peak pixel signal of 23000 ADU seemingly at a safe level of slightly over half full well However seeing fluctuations over these short times could result in good images which push the peak pixel close to saturation Finally note that we are recommending a bias value of 0 7 v over the value of 0 8 v also tested during commissioning since the lower bias appears to give fewer maverick pixels However the saturation level is reduced to 35000 ADU 3 5 Flatfielding The accuracy of flatfield correction 1s still under investigation at this time Linearity tests with bias values of 0 7 and 0 8 v have shown that the ratios of flatfield images taken at different integration times and corrected for nonlinearity section 3 3 are generally within 1 of the expected value The sky background in the Ks and H filters 1s sufficient so that one could generate sky flats from a series of target observations utilizing integration times long enough to yield background signals gt 5000 ADU or so It is necessary to obtain a series of dark frames taken at the same integration time to subtract out any bias or dark current Dome flats are taken with the telescope pointing at the internal dome screen which is illuminated by lamps on the telescope We recommend at least 10 flat images be taken through each filter used for observing these will be combined to reduce the statistical noise In addition we recommend taking an e
9. 40 Ks 2168 0343 0 877 109000 70 270 Lowairglow_____ 1 060 0 0132 0 638 15300 Jos 022 He 1 082 0 0094 0 706 1000 872 863 7 0 0094 0 706 10000 0 25 033 Papo 1280 00 58 0872 15500 13 14 Pa B 4500 km s 1 303 0 0133 0863 13500 08 10 Fem 16s6 0 0164 0791 10500 19 26 Fe 1 4500 km s 1 668 0 0162 0917 11300 25 41 msa 2117 0 0216 0680 7150 24 83 Bry 2 162 0 0215 0 849 750 38 13 Bry 4500 km s 2 188 00237 0 940 80 50 18 13 14 08 10 19 26 25 41 24 83 38 13 50 18 3 3 Linearity All infrared arrays utilizing a unit cell architecture are inherently nonlinear since the potential well created by the application of the bias voltage has a capacitance which increases as the collected charge fills up the well one may think of the two capacitor plates moving closer together In parallel with the capacitance of the rest of the unit cell this yields a gain which varies slowly as the well fills up Under the condition of constant signal flux the plot of signal vs time would begin at a slope near unity and slowly roll off until the array saturates Alternatively one can define a linearity function which is essentially the slope of the signal vs time plot normalized to the value at small signal levels We have carried out a quadratic fit to the linearity function
10. 50arcsec load std 5 Narcsec load std xo 100arcsec load std oxo 100arcsec Focus Seq generator Exit E Automatic display _ Overwrite files observer Meisner observe name test exposure 10 type 0Object number 1 OPAQUE LOW AIR sc BR_G 4500 BR_G FE I 4500 FE JI TF PA B E Fowler 1 hu Fowler 4 Min Exposure secs 3 6 Figure 5 21 The MOP File pull down menu for loading canned or custom observing scripts WHIRC User s Manual Version 1 07 2009 May 28 35 2 Below 1s an example of the MOP after the 5 point cross dither pattern script was loaded Note that the Observe button is now labeled Run Script To run the script through without stopping push on Run Script Or you can push on Step Script to step through useful for the first time or checking The setup below will observe the standard star FS30 in the H band filter in a 5 point cross dither pattern with 50 arcsec separations Comms Opts PAN Help target F530 ra 22 41 50 545 dec 01 12 32 907 Humber of frames 11 observer Meixner Exposure type Object Exposure in seconds Mmatadatlafi sep 00 File name ir Run Step ocrpt ocript E Automatic display _j Overwrite files observe name Ir esposure 30 0 type 0Object number 1 Observing script Momerobserverfobserving sc pis std 3 olarcsec obs Executing Loaded click Run Script to start OPAGUE WHIRC Filters LOW AIR cs BR_G 4500 BR_G FE IL 4500 FE_
11. except for the two filter wheels This design was dictated in part by the stringent instrument envelope and weight requirements of the WTTM port The optical system consists of a five element collimator and a five element camera A fixed cold stop is located at the pupil image formed by the collimator The two filter wheels are located on either side of this stop placing the filters very close to the pupil image in the collimated beam A single LN reservoir provides cooling for the optics and the HgCdTe detector whose temperature is regulated by a servo control loop The detector controller is the Monsoon system developed at NOAO Figures 3 1 and 3 2 show schematics of the instrument and a closeup of the optical assembly WHIRC User s Manual Version 1 07 2009 May 28 4 Vacuum Vessel WTTM Shim Radiation Shield G10 Support Tube Valve Figure 3 1 Assembly drawing of WHIRC The shim is used to adjust the axial location of WHIRC so that the WTTM focal plane is imaged onto the detector G10 Support Tube Filter Wheels Optical Bench Radiation Shield Baffles Window Detector Field Stop Collimator Lyot Stop Camera Figure 3 2 Close up of Fig 3 1 showing the optical elements in more detail WHIRC User s Manual Version 1 07 2009 May 28 5 3 1 Filters The two 8 position filter wheels allow a total of 13 filters Each filter wheel must have one open position and one wheel has an opaque blocker for taking dark
12. flat feii off 154 fits flat Ks on 098 fits whirc log flat_feii_off_155 fits flat Ks on 099 fits whirc temperature log 5 ill pyraf Figure 5 11 PyRAF shell window for data analysis WHIRC User s Manual Version 1 07 2009 May 28 21 8 Ask the observing associate OA to single click on the WHIRC bias icon to bring up the WHIRC bias GUI on the OA s screen This operation is for the telescope operator only The detector temperature must be below 90 K prior to biasing The detector is unbiased at this point and the window appears as below a The temperature should continuously update and the LED is green showing a temperature of 78 5 degrees K Voltages update only on demand by pressing Update Voltages and so have a red LED indicating it is not ready Y WHIRC Detector Biasing Temperature 0078 500 K 4 Voltages EN WIYN Staff use Only 1 Bias Detector Reset Temp Monitor Update Woltages Reconnect to PAN Sep 26 18 13 26 whirc bias Reset temperature monitor b Click on the Update Voltages button screen should confirm that all the voltages are OK The Voltages LED should turn green and read ok Y WHIRC Detector Biasing Temperature 0078 500 K Voltages ok _ Power Detector WIYN Staff use Only 4 Bias Detector Reset Temp Monitor Update Voltages Reconnect to PAN 14 Whirc_bias check Bias Tel 01_iSlew 3 118211 req 3 12 0 075 Sep 26 18 14 47 pan ppxGetAVP Bias Te
13. for 0 7 v bias up to a value of 38000 ADU By inverting this function one can derive a linearity correction function so that the corrected signal S is related to the raw signal S by S S A B S C S where A 1 000 A 1 000 B 1 29x 10 0 004227 C 2 506 x 107 0 02691 The IRAF task irlincor is specifically designed to carry out this correction the coefficients A B and C above are the irlincor values Jt is critical that linearity correction be performed on the raw data prior to any sky or dark subtraction Data obtained using Fowler 4 mode must be divided by 4 prior to linearity correction WHIRC User s Manual Version 1 07 2009 May 28 7 3 4 Saturation Because of the fine pixel scale of WHIRC it is tempting to think that saturation on brighter stars 1s not as critical as for a wide field imager with larger pixels but the combination of a 3 5 m aperture a 4 s minimum integration time and good image quality does mean that one must consider this issue If WHIRC attains its goal performance in conjunction with WTTM it will yield image cores with FWHM lt 3 pixels similar to what one obtains with FLAMINGOS on the 4 m under median seeing conditions The data presented in Table 3 1 were obtained under seeing conditions 0 5 arcsec 5 pixels FWHM Empirically the peak pixel flux was typically 0 03 of the integrated flux within the 1 6 arcsec diameter aperture For a H 10 0 star in the minimum integration
14. frames Table 3 1 lists the filter characteristics as well as the observed signal in ADU s corresponding to a mag 10 0 star determined from observations of the IR standard FS 28 at the current bias level of 0 7 v The sky background levels in ADU s pixel were measured in March and September 2008 at ambient temperatures of 4 C and 23 C respectively The background in the K band filters is dominated by thermal emission and can be expected to vary significantly with temperature In addition the background in the other filters except for the 1 06 and 1 082 um narrowband filters is dominated by OH airglow which can vary a factor of two from the values listed in Table 3 1 Links to tracings of the Individual filters can be found on the WHIRC website http www noao edu kpno manuals whirc WHIRC htm The three broadband filters are standard J H and Ks filters The narrowband filters include those for He I H II regions PNe Br y and Pa B ionized gas Fe II photodissociation regions and PNe H2 S 1 shocked molecular gas and CO cool stellar atmospheres In addition Br y Pa B and Fe II filters redshifted by 4500 km s are used to provide continuum images for emission line imaging in those filters or for observing these emission lines in redshifted galaxies Finally a filter near 1 06 um is located in a region nearly devoid of telluric OH line emission for very low background deep imaging Note The actual WHIRC filters were scanned by
15. if IAS guiding is to be used Verify WTTM dithers disabled message in MOP status window monoge 5 Observer single click start DS9 button a ds9 window opens 6 Observer single click start PyRAF button a PyRAF window opens 7 OA Click WHIRC Bias icon Reconnect PAN Update voltages Power Detector Bias Detector Observer wait until OA says to proceed fC A 0 8 8 Observer Single click start WHOMP button a WHOMP GUI opens WHIRC User s Manual Version 1 07 2009 May 28 25 5 3 Shutting Down WHIRC At the end of the night the MOP PAN and WHIRC Bias tool interfaces should be closed The WHIRC Engineering GUI should be left running on the OA terminal to permit monitoring of the WHIRC temperatures Follow the procedure below to safely shut down WHIRC 1 Using the MOP put the filter wheels into the OPAQUE filter position 2 Ask the observing assistant to unbias the detector using the WHIRC Bias tool window a Unbias the detector by clicking on the Bias Detector radio button A window will pop up and ask you if you want to unbias the detector Click OK to proceed with unbiasing b Unpower the detector by clicking on the Power Detector radio button A window will pop up and ask you if you want to unpower the detector Click OK to proceed with unpowering the detector c Take down the WHIRC Bias tool by quitting the window 3 Inthe PAN window desktop take down the PAN window by quitting the window x on t
16. in WHIRC is operated in a non destructive double correlated sampling mode also referred to as reset read read The cycle involves biasing the detector pixels to the desired bias voltage of 0 7 v The entire array is then read out nondestructively followed by a second nondestructive readout The time interval between the initiation of the first read and the initiation of the second read is by definition the integration time The first readout is then subtracted from the second to provide the single bias subtracted image which is stored on disk This mode of operation which is also referred to as Fowler 1 is used for most observations with WHIRC particularly those where photon noise from either the source brightness or sky background is significantly greater than the detector read noise For observations of faint targets in the narrowband filters one may use the Fowler 4 mode in which the array is read out four times each at the beginning and end of the observation This can reduce the read noise up to a factor of two The minimum possible integration time is by definition the time to read out the array which is 3 77 s For the Fowler 4 mode with four readouts the minimum integration time is increased to 15 2 s For long integrations on faint targets this additional overhead is small and 1s well worth the advantage from the lower read noise 3 0 Instrument Description WHIRC 1s a straight through all refractive imager with no moving parts
17. judgment involved in selecting the individual frame times The use of guiding will increase the overhead by a few seconds per observation but 1s well worth it if the seeing is good 1f one can use longer integration times as a result the guiding overhead is recovered by writing fewer images to disk If the sky is particularly variable more observations at shorter integration times may be preferable The additional overhead of using Fowler 4 vs Fowler 1 1s approximately 12 s per image for integration times gt 60 s use of Fowler 4 is probably warranted except in the H and Ks filters While longer frame times benefit the S N under very low background conditions removal of systematic and cosmetic effects benefits from a larger number of images Thus for a source requiring a total of 60 min of on source time six 10 min frames may be preferable to three 20 min frames 6 2 3 Guiding As noted above guiding with the IAS guider imposes small overheads on operation since the guide probe must move after each telescope motion On the other hand if one is using relatively long gt 60 s frame times the overhead is small and the benefits of better image quality particularly if the native seeing is good are worth it Standard star or bright target observations utilizing 5 20 s frame times are not worth the overhead in WHIRC User s Manual Version 1 07 2009 May 28 45 guide star acquisition and probe motion If one is using WTTM one is alwa
18. subtraction and quality results 6 2 WHIRC Strategies 6 2 1 Dithering Strategies As noted in Section 5 the MOP is able to execute either a single observation typically for setup and focusing or scripts which offset the telescope in between observations One may use one of a number of canned scripts std_ obs those generated by other observers or new scripts designed using the WHOM P sections 5 7 and 5 8 The dimension given in the canned scripts refers to the differential separation not the total extent so the std 5x5 l0O0arcsec obs script executes a 5 x 5 dither pattern centered on the initial telescope position which is 400 arcsec on a side ft is advisable to review a script using a text editor to ensure that it really carries out the desired telescope motions The file names of observer generated scripts may not accurately describe their function e Standard Stars One may use the canned 5 point scripts with relatively small amplitude or the 2 x 2 grid scripts Although we feel that the pupil ghost can be removed from the flatfields during data reduction until this has been verified WHIRC User s Manual Version 1 07 2009 May 28 43 photometrically conservative users may prefer to use the 2 X 2 grid scripts which avoid the center of the array e Science fields with pointlike targets One may use the same scripts as for the standard stars with the same caveat about avoiding the pupil ghost at the center
19. the vendor only at ambient temperature Instead standard size 25 mm witness samples which were coated during the filter run were scanned at both ambient and cryogenic temperatures and the difference between them was used to correct the ambient WHIRC filter parameters to their calculated cryogenic values Because broadband filters often have oscillatory behavior in their transmission curves and narrowband filters of 1 fractional bandwidth rarely have a truly flat region at their peak transmission and may have broad wings the definition of average transmission can be a matter of judgment For the purpose of this table we calculated the integrated transmission under the ambient filter curves and divided by the vendor calculated cryogenic FWHM of the filter to derive the number listed as average transmission Since the product of these is actually used in throughput calculations this is a somewhat artificial definition but the FWHM is an important parameter particularly for the study of high redshift emission line targets 3 2 Signal and Background Levels Table 3 1 below gives the signal and background levels obtained with WHIRC in March T 4 C and September 2008 T 23 C in units of ADU s WHIRC User s Manual Version 1 07 2009 May 28 6 Table 3 1 WHIRC Filter Characteristics Filter Mum AA um lave Signal 10 0 Background mag March Sept poo 250 0162 0913 183000 5 7 Ho i sil 0310 0 867 195000 25
20. 000 10000 15000 20000 Figure 3 3 Flatfields at J left panel and Ks right panel showing the central enhancement from the pupil ghost The ghost is more prominent 25 at Ks than at J 5 The falloff in intensity at the top and bottom of the array is a real sensitivity feature The black columns on the right of each image are reference columns and are not part of the 2048 x 2048 image System Architecture The basic WHIRC system architecture 1s illustrated in Figs 4 1 and 4 2 The Observation Control System WHOCS has three primary functions Interaction with the WIYN telescope o Telescope Control System TCS controls the telescope pointing etc o Instrument Adapter System IAS controls telescope guiding o Telescope focus control o WIYN Tip Tilt Module WT TM on which WHIRC is installed provides fast tip tilt correction using a reference star outside the science field to improve the image quality WHIRC instrument control o Control of the two filter wheel motors o Detector temperature control o Housekeeping functions detector temperature filter status WHIRC detector control The WHIRC detector 1s controlled by the NOAO Monsoon data acquisition system which has two primary components o Detector Head Electronics DHE These run the detector precision reference voltages clock and bias etc The DHE is installed close to the WHIRC dewar itself connected by short cables o Pixel Acquisition Node PAN This i
21. 000000f gt ppxGetAVP Bias Tel 11 vdetCom gt OK ppxGetAVP Success wrtToRead generic Success MA Bias Tel 11 vdetCom 0 992067 lt 0x00000148 gt ppxGetAVP Bias Tel 16 vrstUc gt OK ppxGetAVP Success wrtToRead generic Success Bias Tel 16 vrstUc 0 278926 lt 0x000000ef gt Figure 5 14 WHIRC Detector Bias window after successfully biasing the detector 9 Single click on the start WHOMP icon to bring up the WHIRC Observation Manager and Planner on the Observer monitor The observer can use this window to plan more complex mapping and dithering observations than the small menu of simple dithers and small map provided in the MOP An observing script is created in the WHOMP GUI and this script can be uploaded by the user into the MOP for execution The target name is used for both the header information and as the rootname for the FITS file of the observation The coordinates of the target can be input however at present they are ignored by the MOP and the FITS header takes the telescope systems coordinates for the header KU Wiirc Map Designer File Recipes View WHOMP Version 1 6 30 Nov 2007 Target Name none Target Coordinates Heliocentric Equatorial Coordinates N 4 Equatorial Right Ascension OH H 0 mM 0 000 S 9 Ecliptic Deciination 0D o 0000 v Galactic Rol 0oDj o 0000 Equinox 2000 Map Designer Number of X Cells Number of Y Cells 1 Shape Selector Grid fz J Plus X Cell Spa
22. 600 720 840 West IAS X Axis arcsec East Figure 6 1 Schematic of the IAS guide field with WTTM deployed Vignetting is from the WHIRC WTTM pickoff mirror which is in front of the guide probes 6 2 4 Flatfields Flatfield observations are necessary to calibrate the pixel to pixel variations in the detector array This was discussed in more detail in Section 3 5 In general we recommend that flatfields be obtained each night for each filter used for observing These can be done in the afternoon and do not require the telescope control system to be running We recommend taking 10 images with the flatfield lights illuminating the dome screen and 10 with the lights turned off using the intensity settings in Table 3 2 The averaged lamp off images are subtracted from the lamp on images to remove common signals such as hot pixels and thermal or stray background light While it is possible to generate sky flats from the science images in the H and Ks filters the photometric performance of such flatfields has not been verified One concern is that the pupil ghost Fig 3 3 which is particularly prominent in the Ks filter has a different spatial structure in raw sky images than in the dome flats probably resulting from different contributions of local and sky thermal emission in the two cases Long term monitoring of dome flats has shown them to be spatially stable to within 1 or so whereas no equivalent monitoring of the stability of sk
23. Bry 4500 50 11000 co 00 11000 3 5 1 Pupil Ghosting The WHIRC flat images display a pupil ghost which is an artifact seen in many refractive imagers Unlike image ghosts which arise from multiple reflections of the light from a bright source and manifest themselves as distorted and defocused images of the target which move as the target does the pupil ghost is a fixed feature which comes from multiple reflections of the diffuse background from the sky or telescope pupil The WHIRC pupil ghost 1s significantly more prominent at longer wavelengths Figure 3 3 shows flatfields in the J and Ks filters the pupil ghost can be seen in both but is much more evident at the 25 level in the Ks flat than in the J flat 5 It is important to realize that the higher signal level from the pupil ghost does not represent a real increase in the array sensitivity in that region so using an uncorrected flat will result in photometric errors on the low side for sources within the ghost region We have developed a procedure for removing the ghost using the IRAF mscred rmpupil task but have not yet verified this photometrically For the present we recommend that observers using WHIRC for observations of isolated targets employ observing scripts which avoid the central portion of the array where the ghost is most evident WHIRC User s Manual Version 1 07 2009 May 28 9 2000 4 0 4000 6000 6000 10000 12000 14000 16000 16000 2000 5
24. Designer a Map Repeat 1 File name GLM GC setup2 obs Save Dither Designer Map Dither Design al Y Offset deg si Number of X Dithers Files of type Cancel rs Number of Y Dithers Shape Selector 2 2 Grid Au CA are a mm Plus Plus X Dither Size arcsec Y Dither Size arcsec X Dither Size arcsec Y Dither Size arcsec 30 30 ee 20 20 Dither Repeat 1 Expose Repeat 1 Exposure time s 20 Dither Repeat 0 Expose Repeat 1 Exposure time s 20 wy X Figure 5 25 top panel The WHOMP GUI setup for a 2 x 2 dither script on a target and on a sky position 0 1 degree away in RA and DEC bottom panel The menu for saving the script in the subdirectory home observer observing scripts 5 8 Editing a WHOMP Script The WHOMP is a very versatile tool for setting up complex observing scripts which are customized to specific targets One of the strengths of this tool is the ability to generate observing scripts at one s home institution well in advance of the actual observing run and enter them into the observing scripts directory at the time of the run However for WHIRC User s Manual Version 1 07 2009 May 28 39 relatively simple observations this customized nature can be annoying For example the target name GLM GC in the example shown in Fig 5 25 which 1s written to the file GLM GC setup2 obs and the exposure time 20 s will overwrite any user input to the MOP once the observing script
25. Il TT PA B Fowler 1 Fowler 4 Min Exposure secs 3 6 Figure 5 22 The MOP after loading an observing script WHIRC User s Manual Version 1 07 2009 May 28 36 3 Once the script 1s running Run Script will turn into working during an exposure To stop a script from running click on Pause Script and Abort in that order because if you click on Abort first you will confuse the system and may need to restart the MOP If you pause a script you can resume it by clicking on the Resume Script button which will appear once the script is paused To get completely out of the script and back to single observation mode or a different script open the pull down menu with the File button menu and select Unload current script Comms Opts PAN Help target F530 ra 1422 41 50 558 dec 01 11 57 650 Humber of frames 11 observer Meixner fdatandatais sep 06 File name ir Exposure type Object Exposure in seconds ee Pause Working Script E Automatic display _j Overvnite files observe namesir exposure 30 0 type sObject number 1 Observing script homesobserverfobserving scnpis std 5 o0arcsec obs Executing observe qui image name gui exp time gui exp type gui num frames Hext command offsetscope adjust 35 909 39 300 OPAQUE WHIRC Filters LOW AIR cs BR G 4500 BR_G FE I 4500 FE II ET PA B E Fowler 1 hu Fowler 4 Min Exposure secs 3 0 Figure 5 23 The MOP with an obser
26. MOP status window automatically loaded with the MOP WHIRC User s Manual Version 1 07 2009 May 28 19 d The WTTM client window This will be used in conjunction with WTTM operation once this is supported If one is not using WTTM the window can be iconified to reduce clutter However if IAS guiding is desired the Disable WTTM button on the WTTM client window must be selected first The message WTTM dither disabled should appear in the MOP status window Guider const Dither step size Wait between OK servo error Arcsec Pixel Go to x y pixel while dithering pixels steps msec pixels Offset rauo fi fi 5 200 la fi 0 20408 Seve WETH _j Guided dithers currently X 563 Y 1033 Disable WITM all Figure 5 9 The WI TM Client GUI also automatically loaded with the MOP Select Disable WTTM to permit IAS guiding WHIRC User s Manual Version 1 07 2009 May 28 20 6 Single click on the start DS9 button to bring up the ds9 display window Images are automatically displayed after they have been taken by the MOP v SAOImage ds9 CE File Edit Frame Bin Zoom Scale Color Region WCS Analysis Help File Value Po r WCS Physical x Y Image x Y Hamel 00m 1 UUU Ang U UUU File Edit Frame Bin Zoom Scale Color Regin wcs about open savemg savems savempeg header source pmmt page exit
27. P default is to NOT overwrite files If an exposure creates a file which duplicates a name in the data directory the MOP will query for permission to overwrite the file One may also set the Overwrite files button to force overwriting but this is not advisable so use this option with extreme caution The Overwrite files option overwrites in place Le Selecting 10 frames will yield only a single file although the separate images will be displayed as they are completed and it will do this silently without verification WHIRC User s Manual Version 1 07 2009 May 28 29 2 Click the Observe button to start the observation The MOP will change its appearance so that the Observe button turns green and says working Adjacent to this button an Abort button appears You can click on the Abort button if you wish to stop or cancel your observations This will bring up a window asking to confirm the abort operation Ka Monsoon Camera Control EEE EEO EEE OEE ae WET TA Comms Opts PAN target dark ra 05 13 24 51 dec 0r ie 722 995 Number of frames 4 observer Meisner idatardatari Sep 00 File name dark 100s a4 E Automatic display J Overwrte files Exposure type Dark Exposure Lin seconds 3 100 observe name dark_100s exposure 1 00 type Dark number 4 LOW AIR e BR_G _4500 BR_G FE II 4500 FE II arg PA B Fowler 1 hn Fowler 4 Min Exposure secs 3 0 Figure 5 17 WHIRC MOP with an exposure
28. Tel 04 vhiRo Q Bias detector Sep 26 18 16 13 pan gt OK ppxGetaVP Success Sep 26 18 16 13 whirc bias check Bias Tel 04 vhiRowE Sep 26 18 16 13 pan ppxGetaVP Bias Tel 11 vdetCo Sep 26 18 16 13 pan gt OK ppxGetAVP Success OK Cancel MA Bias Tel 11 vdetcom 0 992067 lt 0x00000148 gt Sep 26 18 16 13 pan ppxGetAVP Bias Tel 16 vrstUo Sep 26 18 16 13 pan gt OK ppxGetAVP Success Sep 26 18 16 13 pan ppxGetAVP CLKO_OUTPUTEN Sep 26 18 16 13 pan gt OF ppxGetAVP Success CLKO_OUTPUTEN 15 J00 lt 0 0000000f gt Sep 26 18 16 13 pan ppxGetAVP CLKO_OUTPUTEN Sep 26 18 16 13 pan gt OK ppxGetaVP Success YA CLKO_OUTPUTEN 15 J00 lt 0x0000000 gt Sep 26 18 16 13 pan ppxGetAVP Bias Tel 11 vdetCom Sep 26 18 16 13 pan gt OK ppxGetaVP Success YA wrtToRead generic Success Bias_Tel_11_vdetCom 0 992067 lt 0x00000148 gt Sep 26 18 16 13 pan ppxGetAVP Bias_Tel 16 vrstUc Sep 26 18 16 13 pan gt OK ppxGetAVP Success YA wrtToRead generic Success MA Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Sep 26 18 16 29 pan ppxGetAvP CLKO OUTPUTEN Sep 26 18 16 29 pan gt OK ppxGetAVP Success VA CLKO_OUTPUTEN 15 J00 lt 0x0000000f gt Y Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt YA Bias Tel 04 vhiRovEn 4 970169 lt 0x0000033 gt MA Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Figure 5 13 WHIRC Detector Bias w
29. WIYN High Resolution Infrared Camera WHIRC User s Guide Dick Joyce Margaret Meixner Todd Miller Edward Churchwell Version 1 07 2009 May 28 Vacuum Vessel WTTM Shim y 7 ze ki p J Broke Se By Seo oe RAP Pept 3 MA An A af Radiation Shield G10 Support Tube WHIRC User s Manual Version 1 07 2009 May 28 1 ACRONYMS AND ABBR VENTION S ia wa e a e a NAA 2 1 0 INTRODUCTION wa AA AA Au AA IA WA AA AA 3 2 0 USEFULEFACTS ia 3 3 0 INSTRUMENT DESCRIPTION s0s0s0ss0s0eee 4 3 1 O II AA NR AT 6 32 SIGNAL AND BACKGROUND LEVELS E 6 3 3 IAIN RT serie o dre ne die on tras end 7 3 4 SATA TIO IN E E E e ce e da e Nara TN 8 3 5 EAT E E e ee da leon to eto 8 4 0 SYSTEM ARCHITECTURE ute 10 5 0 OBSERVING WIH WHIRO aesir aaraa ais 12 5 1 STARTING UP WHIRC FROM SCRATC o a dee ea eo lO 12 52 SHORT SUMMARY OF NORMAL WHIRC START UP SEQUENCE ccooccnoconoccnnccnnoconancnnncnnaconaronunonons 25 5 3 SHUTTING DOWN WW TEER OEE E AAA Act lo de e e ATA 26 5 4 TROUBLESHOOTING PROBLEMS WITH MOP PAN OR WHIRC BIAS DURING STARTUP 27 5 5 TAKING AN OBSERVATION USING THE MOP cccccscecceccecceccccecceccscescescescecescesceseecescuscuseess 28 5 6 USING THE MOP WITH AN OBSERVING SCRIPT ccceccecceccscesceccecesceccccectecescescestecescestscesceseeses 34 SF MAKING AN OBSERVATION SCRIPT USING THE WHOMP 0 cecc
30. c from the pull down menu of options d Set Exposure time Type or use arrow radio buttons to change the exposure time to the desired value NOTE the exposure time input should not be smaller than the minimum time for the particular readout mode which is noted at the bottom of the MOP For safety we recommend minimum integration times of 4 s for Fowler 1 and 16 s for Fowler 4 e Change the Number of frames or repeated observations if desired This 1s particularly useful for flatfields or darks where multiple observations are necessary f Type in the name of the object in the target field The ra and dec fields are updated automatically from the Telescope Control System h The File name dark 100s in Fig 5 16 is the basename of the FITS file created by the observation One may set this by changing the File name and or the number 57 The number will automatically index after an exposure 1s taken If you set the File name and the extension to that of an existing image the MOP will ask if you wish to overwrite after completing the exposure 1 Set the directory into which the FITS files are written after the observation 1s complete When the MOP is brought up it will automatically update the data directory to the current date in the format lt dd gt lt Month gt lt yy gt j One may turn off the automatic display into ds9 by unchecking the Automatic display button The MOP default is to automatically display the image k The MO
31. cfglnit already initialized FDEG cfgInit ending FDEGA panDaemon After detInit status 0 FDEGA panDataProcAlg entering 0 FDEGA Starting panCapture FDEGA panMemInitNotDaemon attached _panMemP Oxb7fSe000 FDEGA panImgBufferInit create 0 FDEGA cfgInit starting DEG cfgInit I attach succeed libcfglmds FDBGA cfgInit I attach pointer 0xa2596000 FDEG cfgInit I attach processes 3 FDEG cfgInit already initialized DBGK cfgInit ending FDEG panDaemon After detInit status 0 FDEGA In Child Starting panTriogerExp process 0 FDEGA In Parent Calling pantaptureData process 8397 FDEGA Entering panDataCapture 0 FDEGA Starting panSaver FDEGA panMemInitNotDaemon attached _panMemP Oxb7f4c000 FDEGA panImgBufferInit create 0 FDEGA cfglnit starting DIEG cfgInit I attach succeed libcfglmds DIEG cfglnit I attach pointer 0xa2554000 DEG cfgInit I attach processes 1 DEG cfglnit already initialized FDEGA cfglnit ending FDEGA panDaemon After detInit status 0 FDEGA Entering panDataSaver FDEGA Entering panGetImgParams FDBGA Leaving panGetImgParams istat 0 Figure 5 5 Successfully initialized PAN window on the observer s monitor WHIRC User s Manual Version 1 07 2009 May 28 17 5 Single click on the start MOP button to bring up the Observer s Interface window a Fig 5 6 the MOP debug log window b Fig 5 7 the MOP status window c Fig 5 8 and the WTTM
32. cing arcsec Y Cell Spacing arcsec 180 180 7v Xx HE O E OS Map Repeat 1 Sky Dither Designer Map Dither Designer X Offset deg 1 Y Offset deg 1 Number of X Dithers Number of Y Dithers Shape Selector Number of X Dithers Number of Y Dithers Shape Selector 1 1 1 4 Grid i AA aT Plus X Dither Size arcsec Y Dither Size arcsec X Dither Size arcsec Y Dither Size arcsec 20 20 20 20 ia Et 2 uu Be a ee Dither Repeat 1 Expose Repeat 1 Exposure time s 1 Dither Repeat 0 Expose Repeat 1 Exposure time s 1 Figure 5 15 The WHIRC Observation Manager and Planning WHOMP GUI WHIRC User s Manual Version 1 07 2009 May 28 24 5 2 Short Summary of Normal WHIRC Start Up Sequence 1 Observer Single click MASSIVE CLEANUP button to clear out any ongoing processes 2 Ask OA to single click the WHIRC Engineering window and check a Temperature Control window b Filters window c Temperature Status window d Wait until OA says to proceed 3 Observer Single click start PAN button a Wait for all 4 windows to open b Be sure there are no errors c If errors click clear PAN button then start PAN button again 4 Observer single click start MOP button MOP debug log window appears make sure there are no errors MOP status window appears MOP control panel appears Wait until Filter status windows are green WTTM client window appears may be iconified if WTTM not used Select Disable WTTM button
33. client window d Fig 5 9 Note If the XTCS is not running on the OA s computer you will get a pop up stating that the XTCS cannot be contacted For the purpose of doing afternoon calibrations and dome flats the XTCS is not needed and you can click Continue However the XTCS must be running in order for WHIRC to do on sky observations a MONSOON Observing Platform This panel is the Observer Interface for observing with WHIRC User inputs include the exposure time filter position detector readout mode object name and observer The RA and DEC are supplied by the WIYN TCS The File pull down menu is used for loading standard dither scripts or a custom observing script file WTTM Comms Opts PAN Help target dark ra 16 03 04 92 dec 02 00 40 624 Number of frames 20 observer idata datafi Sep 06 File name dark_5s J0 Observe E Automatic display J Overunte files observe ame dark_os exposure 9 0 type Dark number zo Exposure type Dark Exposure in seconds 5 0 LOW AIR mes open H2 BR_G_4500 BR_G FE 11 4500 FE JI PA_B_4500 PA B Fowler 1 hu Fowler 4 Min Exposure secs 3 6 Figure 5 6 The Monsoon Observing Platform for WHIRC WHIRC User s Manual Version 1 07 2009 May 28 18 b MOP debug log This window displays the status of the MOP commands and is useful to help debug issues when observations do not work Ka MOP debug log waiting 244 1 lexp 2243 pixelsllone
34. e sequence At the end the command offsetScope adj 15 15 will move the telescope back to the initial position NOTE This is now the default syntax created by the WHOMP 5 8 2 WHOMP Observing Syntax As noted above an observing script created by WHOMP will contain the source information within the observe command and this will overwrite any observer entry on the MOP The syntax of the command 1s observe lt File name gt lt integration time gt lt Exposure type gt lt frames gt To set up the script for a particular target one may substitute the desired lt File name gt and lt integration time gt at each occurrence in the generic script In general the Exposure type Object and frames 1 so these would be edited less frequently It 1s also possible to edit the script to use the entries from the MOP which may be the most convenient approach observe gui image name gui exp time gui exp type gui num frames WHIRC User s Manual Version 1 07 2009 May 28 4 6 0 Observing Strategies Imagers and spectrographs utilizing infrared arrays have been a part of the astronomical toolkit for over 20 years and most experienced observers are familiar with the techniques used for infrared observing For novice observers the book Astronomical CCD Observing and Reduction Techniques ASP Conference Series Vol 23 1992 ed Steve Howell remains a good introductory text with a chapter describing the use of infrared arrays o
35. e windows onto any of the three panels of the display as they come up For completeness the windows which display on the OA terminal will be described even though they are reserved for use by WIYN personnel only 1 Log into the computer dust with the username observer and the password posted on the terminal This will bring up the monitors The middle monitor has a toolbar on the left side see figure at left with buttons for opening up the standard KDE and observer initiated processes 2 At the start of each night the observer should execute a MASSIVE CLEANUP using the button on the lower left of the toolbar This will clear out any extraneous background processes which might be left over from the previous night Sometimes executing the MASSIVE CLEANUP two or three times is necessary to clean things up completely 3 Ask the observing assistant to single click on the WHIRC Engineering icon on the OA s screen to bring up the WHIRC Engineering GUI which shows status and provides control over the filter wheels and temperature control for WHIRC These windows are for use by the WIYN staff only not by general observers There are four tabs 02 29 pm 04 16 08 WHIRC User s Manual Version 1 07 2009 May 28 12 a Options a text status page on the filter and temperature control subsystems Fig 5 1 Jl whinc SE Fillers temperature Cunku temperalure Status use Onl Sage Of 17 5 A 2 yA naza Lima msl map
36. eccececcecceccecescesceccecescesceses 38 5 8 EDITINGA WHO MB RA e de e la OS 39 6 0 OBSERVING STRATEGIES s s sssses0eee 42 6 1 TR STRATEGY IN GENERAL iza 42 6 2 A A asi sade seas celia banca a e a 43 7 0 WTEM OPERATION SUS ee 49 7 1 WT EVE DESCRIPTION a a en e bt ad 49 FA USNO VW aa O RN pa WA 51 Acronyms and Abbreviations DHE FITS GUI IAS MOP PAN OA TCS WHIRC WIYN WHOCS WHOMP WTTM WHIRC User s Manual Version 1 07 2009 May 28 Detector Head Electronics MONSOON system Flexible Image Transport System image standard Graphical User Interface Instrument Adapter System MONSOON Observing Platform Pixel Acquisition Node computer controls MONSOON Observing Associate Telescope Control System WIYN High Resolution InfraRed Camera Wisconsin Indiana Yale NOAO Observatory consortium WHIRC Observation Control System WHIRC Observation Manager and Planner WIYN Tip Tilt Module WIYN High Resolution Infrared Camera WHIRC User s Guide 1 0 Introduction The WIYN High Resolution Infrared Camera WHIRC is a near infrared 0 9 2 5 um imager which installs on the WIYN Tip Tilt module WTTM port The 0 1 arcsec pixel scale and 3 3 arcmin field of view are designed to take advantage of the excellent native seeing at the WIYN site and the near diffraction limited image quality 0 2 arcsec which WTTM is expected to deliver in t
37. eps of 15 to 20 until one 1s equally out of focus on the other side Because of the off axis WITM optics the focus behavior is not symmetric It should then be possible to iterate around the best focus with smaller steps as small as 5 units when seeing is good The focus of WIYN will change with temperature so one should monitor the image quality while observing and touch it up if necessary in general the focus readout value must be increased as the temperature drops If doing a long sequence of relatively short integrations one can try bumping the focus by 10 to 15 units and monitoring the improvement or lack thereof while continuing to observe and iterating while taking data sometimes this is more efficient than stopping the observing sequence and running through the focus optimization It is worth noting that the thermal temperature gradient within the primary mirror from the front plate to back web dominates over other focus variations and 1s very difficult to predict Once the entire glass has settled to near ambient temperatures focus variations will stabilize WIYN monitors only the temperature difference between glass and ambient air The telescope focus will also change with elevation angle the WIYN telescope control system will compensate for this using a lookup table but it is still a good idea to check the focus when moving a significant distance to a new science field Naturally one is more sensitive to focus changes when
38. etting using the IAS guide probe Operation is the same as with the Enable WTTM button Guided dithers This is used to control the way in which WTTM executes scripted offsets o Guided dithers disabled This operates MOP scripts in the same way as with the IAS guider in which the WTTM guiding is disabled prior to a telescope offset the telescope offset and corresponding error sensor probe motion occur independently then the WTTM guiding is re enabled to recapture the guide star This is the most efficient and recommended method of using WITM Guided dithers enabled MOP scripts command the WTTM to maintain guiding and to drag the field using the error sensor and x y stage This can be useful for small offsets using guide stars near the faint limit but has significant time overhead The motion occurs in 1 5 arcsec steps each taking 1 25 s to execute thus a 15 arcsec offset requires 12 5 s Offset Dither This is used to offset the telescope under WTTM error probe control This should be used for executing a MOP script multiple times on a deep field with small offsets between each dither pattern or for any small offset while guiding with WITM Asking the OA to offset the telescope in the normal manner will result in losing the WTTM guide star 7 2 3 WTTM Operation Observers planning on using WTTM should come prepared with guide star information for each of their fields as well as realistic expectations of the improvements
39. he 2 micron band A selection of wide and narrow band filters allow WHIRC to achieve a broad range of scientific goals in stellar physics star forming regions and the ISM in galactic and extragalactic sources This document is a general purpose User Manual for WHIRC observers containing some general information on the instrument instructions for starting up the instrument from the WIYN observer s station and taking observations Starting up the instrument involves interaction between the observer and the Observing Associate OA so all steps will be described even though some of them are executed by the OA and not by the observer Some of the engineering level observing screens which appear only at the OA station will also be described since they appear as part of the normal startup but they are not for use by the observers 2 0 Useful Facts The table below summarizes some facts about WHIRC During the commissioning of WHIRC we experimented with several values of the detector bias and settled on a value of 0 7 v This has demonstrated good linearity behavior and is currently a good compromise between the number of isolated noisy pixels and the detector well capacity Table 2 1 WHIRC Information Detector Raytheon Virgo HgCdTe 2048 x 2048 _ Detector Gain Readout Modes Readout Modes Fowler 1 Fowler4 Detector Gain___ 4 0 e ADU 0 7v bias WHIRC User s Manual Version 1 07 2009 May 28 3 The infrared array
40. ical signals which one 1s trying to measure with the exception of the Low Airglow and He I narrowband filters e Unlike CCDs which read out by scanning the charge across the array to a readout amplifier infrared arrays are based on unit cell architecture in which each pixel is independent of the others Sensitivity and dark current can vary from pixel to pixel on the array The first of these suggests that the technique of flatfielding a raw image to yield a constant flat sky level is insufficient since even small errors in the flatfield function would yield residual structure larger than the signals of interest Therefore one must subtract as much of the background as possible as part of the data reduction The existence of isolated dead insensitive or hot pixels will compromise the measurement of any source which happens to fall on one of these pixels WHIRC User s Manual Version 1 07 2009 May 28 42 Both of these problems and others are addressed by taking multiple exposures of the field with small telescope motions in between This technique usually referred to as nodding or dithering is a standard infrared observing technique In a relatively sparse field the sky level for each object is measured by the other observations since the sources will be at different locations on the detector By the same token the effect of dead or noisy pixels at specific locations on the detector can be eliminated by moving the
41. imited operation either from the source flux bright targets or the sky background faint targets One will also want to keep the peak signal from either the source or the background well away from saturation so that the linearity 1s well behaved a good rule is lt 25000 ADU e Standards and bright targets The numbers in Table 3 1 can be used to estimate the expected integrated signal from the source The peak flux will of course be very dependent on the seeing we have found that for images with FWHM 0 5 arcsec the peak pixel flux is 0 03 of the integrated signal However a brief episode of 0 4 arcsec seeing will double this value so one should be somewhat conservative when the seeing is good Keep in mind that the minimum integration time is 4 s so standards should not be much brighter than 10 0 for broadband observations in good seeing By the same token it 1s preferable to use standards which can be observed in short integration times to minimize the overhead If doing broadband and one or two narrowband filters it may be more efficient to use longer 60 s integration times for the narrowband filters so one can observe a single standard in all filters If one is observing through a large number of narrowband filters 1t may be more efficient to find a brighter standard for those observations WHIRC User s Manual Version 1 07 2009 May 28 44 e Faint targets o Broadband Filters J H Ks One will generally want to pick an e
42. in progress WHIRC User s Manual Version 1 07 2009 May 28 30 3 An exposure countdown window will pop up and count down the seconds of the exposure time If multiple frames or repeats are selected the Frame number will index After the exposure time completes three messages will appear in sequence to note the processing steps of the data a the detector head electronics DHE will be read b the Fowler frames taken before will be subtracted from the Fowler frames taken after the exposure c the FITS file 1s created and stored on the disk Fa x A RCRRQQA A IOA AAA AA QRQRER 2 countdown he e oo AAA HA countdown he OA n countdown countdown k Figure 5 18 Countdown screen during an exposure DHE read and disk writing WHIRC User s Manual Version 1 07 2009 May 28 31 4 The FITS file created is automatically displayed into ds9 if the Automatic display button is checked Typing imexam in the PyRAF window will put a cursor in the ds9 window which can be used to analyze the properties of the stars such as full width half maximum FWHM when doing a focus check Two examples of a ds9 window are shown below Figure 5 19 1s an almost blank field of uniform sky emission that shows the detector artifacts well The black columns on the right are the detector reference pixels The faint vertical black columns are the first columns of the sect
43. indow during the Power Detector top panel and Bias Detector bottom panel procedures e After successfully biasing the detector the window looks like the following all green lights and one is ready to observe WHIRC User s Manual Version 1 07 2009 May 28 23 W WHIRC Detector Biasing Temperature 0076 609 K Voltages vrstUc E Power Detector W Bias Detector WIYN Staff use Only Reset Temp Monitor Update Voltages Reconnect to PAN whirc bias check Bias Tel 16 vrstUc 0 286939 req 0 0 0 075 pan ppxGetAVP Bias_Tel_16 vrstUc pan gt OK ppxGetAVP Success wrtToRead generic Success E Bias_Tel_ 16 vrstUc 0 286939 lt 0x000000 0 gt whirc_bias ERROR Unexpected voltage on Bias Tel 16 vrstUc 0 28693 pan ppxGetAVP Bias Tel 04 vhiRowEn pan gt OK ppxGetAVP Success YA wrtToRead generic Success YA Bias Tel 04 vhiRowEn 4 970169 lt 0x0000033f gt whirc_bias check Bias Tel 04 vhiRowEn 4 970169 req 5 0 0 075 ppxGetAVP Bias Tel 11 vdetCom gt OK ppxGetaVP Success wrtToRead generic Success Bias Tel 11 vdetCom 0 992067 lt 0x00000148 gt ppxGetAVP Bias Tel 16 vrstUc gt OK ppxGetaVP Success wrtToRead generic Success Bias Tel 16 vrstUc 0 278926 lt 0x000000ef gt ppxGetAVP CLKO_OUTPUTEN gt OK ppxGetAWP Success YA CLKO_OUTPUTEN 15 000 lt 0x0000000f gt ppxGetAVP CLKO_OUTPUTEN gt OK ppxGetaVP Success YA CLKO_OUTPUTEN 15 000 lt 0x0
44. ing and mapping one may use a canned script or load a custom script made with the WHOMP To load the script use the pull down menu from the File button d b The std_x5_50arcsec obs does a 5 point X pattern on the array with 50 arcsec separation between the corner points The std_3x3_50arcsec obs does a 3x3 box pattern on the array with 50 arcsec separation between the points The std 45 50arcsec obs does a 5 point cross pattern on the array with 50 arcsec separation between the points The std_5x5_100arcsec obs does a 5x5 box pattern on the array with 100 arcsec separation between the points The Focus Seq generator opens a window to make a focusing sequence image with steps at different positions on the detector and different focus settings for the telescope This is currently not operational To load a custom made script e g by the WHOMP select Load observing script from the File pull down menu and search the directory area for your script file The home observer observing scripts subdirectory contains the canned and custom observing scripts To unload any script 1 e to get out of script observing mode select Unload current script from the File pull down menu WHIRC User s Manual Version 1 07 2009 May 28 34 e Monsoon Camera Control whirc 3 3 Comms Opts PAN Help KA A target Alpha Nut Load Observing script a er san0 70 Unload current script der TERA load std x5 oQarcsec F load sid 3x3
45. io ce mow Ty halar Ecp 2 17 z 5 loading Log 1044 sep 26 17 50 hi loading 2000 sep 20 17 50 30 vhire gt WANNLNG shippiny slianyy lvy avuvid Sage 2h T A 3 EIA D 26 17 50 whi 2 Starting whircd 26 17 50 ze init complete 17 50 gt init vuaplele wl E init complete init complete gt seyisler_uywe whiiu_sunvel gt vwuwuling lu Lumpuculuso whic connecting to guusmetez vhico comfirmrina mmsawlimyj 2 magit gt Cummarndang 3 cullecl_liller_slulus 1 connecting to fvl vhirc comnarting tn fe whirr mahiri Teepeedisne island IAT court Sella Lemperalure curilivlle slale Lu IDLE vhircd command executing 2 oy whired command axacaiting 2 enl lart filtar atatne l whired enllenting atatua for filter hori el Field X return 600 1 commanding 4 SA Silber akaa 2 meara namal ig 4 nnl lasl Filisa slalo 2 enllenting atatua for filter vherl 2 field z returning 022 1 commanding 45 collect temperature status gt meara rro 5 enl hasl bemp alam dao ammang fh ant Ampie period 2 11 command executing 6 set sample period 2 0 state JULE sp qoal 070 500 0 sp 070 500 0 detector 0070 199 error 000 001 heater 0000 245 gt wbrra ral xlalm TIE SS UU Li SET SO ET MIE SII TL kasali LS Debug Info Debug evel a liter 7 Miler 2 Quil 15344 Tenmperalure contre coenam L3160 Gaussmeter E ivy wulysc uli W cro beep Ucor Status
46. ion of the detector read out by a particular amplifier The speckling of black and white dots are low sensitivity regions and hot pixels The white horizontal lines are hot rows YA a0lmaqedss File Edit View Frame Ein Zoom scale Color Region WCS Analysis file edit view frame bin zoom scale color region WES help center align in out to fit none E y ay O degrees 90 degrees 150 degrees 270 degrees 10000 15000 20000 25000 30000 35000 40000 45000 S0000 Figure 5 19 ds9 display of nearly blank field showing detector artifacts The dark columns on the right are reference pixels and are not part of the image WHIRC User s Manual Version 1 07 2009 May 28 32 The image in Fig 5 20 is of the Trapezium in the Orion Nebula While the trapezium stars themselves are saturated many fainter stars and the HII region nebulosity show brightly 540 lmage ds9 File Edit View Frame Ein Zoom Scale Color Region WCS Analysis File orion 0 186 fits Object Orion Trapezium Value WCS Physical Image file edit view frame bin zoom scale color region WES help center align int out to fit none x y ay O degrees 90 degrees 1500 degrees 270 degrees E 04 3E 04 4F 04 Figure 5 20 ds9 display of an image of the Trapezium in M42 WHIRC User s Manual Version 1 07 2009 May 28 33 5 6 Using the MOP with an Observing Script 1 For a more automated approach to dither
47. is loaded so if one wished to use the same geometric pattern for a different target and or at a different integration time one could not simply load the script and change the File name and integration times in the MOP as they would revert to those in the script once the observing started However the target name in the MOP will not be changed One approach is to generate a generic WHOMP script with the desired pattern then copy it to a scratch script which can be edited to change parameters For example consider the 2 x 2 standard star dither script shown in Fig 5 24 but stored with a generic name such as n1 or ir If one opens up the script nl obs in the former case with an editor one will find a series of four telescope motions and observations each of the sort offsetScope set 15 00 15 00 rotatorAngle 2 47e 16 observe nl_0 50 Object 1 Both the telescope offset and the observing sequences can be edited to carry out a variety of observations NOTE The default observing scripts created by the WHOMP version 1 6 have changed since the User s Manual v1 01 was written 5 8 1 Coordinate Systems in WHOMP Scripts In general when one offsets the telescope to a new target 1t may not end up centered exactly on the array If this 1s important for example if one wants to run a dither script with the target symmetrically positioned about the center of the array one can determine the offset of the star from the a
48. issioning nights Courtesy C Corson and H Schweiker 7 2 2 WTTM Control The details of WTTM operation are handled by the OA but there are several functions which must be done by the observer using the WTTM Client GUI which appears automatically when the MOP is started up Fig 5 9 Fig 7 4 The WTTM probe controller has been referenced to the WHIRC field so the x y coordinates of the guide star in the WHIRC image are used as input to WTTM to acquire the guide star Guider const Dither step size Wait between OK servo error Arcsec Pixel Go to x y pixel while dithering pixels steps msec pixels ratio Offset 1 2 115 200 ja 110 20408 4 Guided dithers currently K 563 Y 1033 Disable WITM Figure 7 4 The WTTM Client GUI which appears during MOP initialization Same as Fig 5 9 WHIRC User s Manual Version 1 07 2009 May 28 32 The currently relevant WTTM Client commands are Enable Disable WTTM The WHIRC MOP interface must know which method to use for guided observations o Enable WTTM This must be pushed in order to enable WTTM fast guiding and offsetting When pushed the button will stay depressed and grey for several seconds and will return to its normal color There is no visual feedback on whether WTTM is enabled or not but the MOP Status Window will echo WTTM dithers enabled when this completes successfully Disable WTTM This must be pushed to disable WTTM guiding and to permit guiding offs
49. l 16 vrstUc Sep 26 18 14 47 pan gt OK ppxGetAVP Success YA wrtToRead generic Success MA Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Sep 26 18 14 47 whirc bias check Bias Tel 16 vrstUc 0 976042 req 1 0 0 075 Sep 26 18 14 47 pan ppxGetAVP Bias Tel 04 vhiRowEn Sep 26 18 14 47 pan gt OK ppxGetAVP Success wrtToRead generic Success Bias Tel 04 vhiRowEn 4 970169 lt 0x0000033f gt Sep 26 18 14 47 whirc bias check Bias Tel 04 vhiRowEn 4 970169 req 5 0 0 075 Sep 26 18 14 47 pan ppxGetAVP Bias Tel 11 vdetCom Sep 26 18 14 47 pan gt OK ppxGetaVP Success wrtToRead generic Success YA Bias Tel 11 vdetCom 0 992067 lt 0x00000148 gt Sep 26 18 14 47 pan ppxGetAVP Bias Tel 16 vrstUc Sep 26 18 14 47 pan gt OK ppxGetAVP Success wrtToRead generic Success YA Bias_Tel_16_vrstUc 0 976042 lt 0x00000146 gt Sep 26 18 14 47 pan ppxGetAVP CLKO_OUTPUTEN Sep 26 18 14 47 pan gt OK ppxGetAVP Success MA CLKO_OUTPUTEN 0 000 lt 0x00000000 gt Sep 26 18 14 47 pan ppxGetAVP CLKO OUTPUTEN Sep 26 18 14 47 pan gt OK ppxGetAVP Success YA CLKO_OUTPUTEN 0 000 lt 0x00000000 gt Sep 26 18 14 47 pan ppxGetAVP Bias_ Tel 11 vdetCom Sep 26 18 14 47 pan gt OK ppxGetAVP Success wrtToRead generic Success Bias Tel 11 vdetCom 0 992067 lt 0x00000148 gt Sep 26 18 14 47 pan ppxGetAVP Bias Tel 16 vrstUc Sep 26 18 14 47 pan gt OK ppxGetAVP Succe
50. lt 0x00000000 gt Sep 26 18 14 47 pan ppxGetAVP CLKO OUTPUTEN Sep 26 18 14 47 pan gt OK ppxGetAVP Success AV CLKO_OUTPUTEN 0 CO00 lt 0x00000000 gt Sep 26 18 14 47 pan ppxGetAVP Bias Tel 11 vdetCom Sep 26 18 14 47 pan gt OK ppxGetAVP Success wrtTcRead ceneric Success YA Bias Tel 11 vdetCcom 0 992067 lt 0x00000148 gt Sep 26 18 14 47 pan ppxGetAvP bias Tel 16 vrstuc Sep 26 18 14 47 pan gt OK ppxGetAVP Success wrtTcRead ceneric Success YA Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Ww check Bias Tel 01_iSlew 3 2 Power detector Bias Tel 16_vrstUc 0 976042 lt 0x00000146 gt MA Bias Tel 04 vh RowEn 4 970269 lt 0x0000033 gt MA Bias Tel 11 vdetCom 0 992067 lt 0x00000148 gt d Click on the Bias Detector button which should turn green Bias the detector by clicking on OK in the query window This is the final step in biasing the detector Ifthe detector temperature 1s above 90 K a warning message will be displayed to not proceed NOTE THE DETECTOR MAY BE DAMAGED IF BIASED AT TOO HIGH A TEMPERATURE lv WHIRC Detector Biasing 5 x Temperature 0078 501 K Voltages ok E Power Detector W Bias Detector WIYN Staff use Only Reset Temp Monitor Update Voltages Reconnect to PAN Sep 26 18 16 13 pan gt OK ppxGetAVP Success Sep 26 18 16 13 whirc_bias check Bias_Tel 16 vrstUc r Sep 26 18 16 13 pan ppxGetAVP Bias
51. n of WHIRC The detector has a heater that keeps the detector temperature stable within 10 mK when cold ensures that the rate of warmup and cooldown of the detector is no more than K per minute and ensures that the detector temperature is above that of the other components in the instrument to prevent condensation of any outgassing constituents on the detector The Monitors window lists a snapshot of the temperatures for the different components in the system The Status window shows the current LakeShore temperature controller parameter values The Commands window is used to command the start of warmup and cooldown sequences reset the temperature control and turn off the heater The Parameters window 1s for entering the PID coefficients and temperature set points in order to modify the control response of the LakeShore heater controller as a function of the measured detector temperature Uplurrs Fillers Lemperalure Cuntrul Hemperalure Status Monitors Status delecior UUTS 493 K stale IDLE virgo LEIA FPS OK sw err uplgal bench 0077 120K selpuirl ANA SAN eK rad shiek ANA RANSK setpoint goal ANTR SAN lt colimator nana Ann Ke rate ann NAR t t k t Eimin cold plate 0076 709 K tolerance 0000 010 K camera 0076 709 K p 0500 000 k 0100 000 k d 0000 000 j heater power 0000 245 watts mak power 0006 220 watts motor_plate 0076 952 K fiter _motor 0077 071 K fiter2_motor 9077 042
52. n page 258 The comments presented here will be a brief summary of general strategies with specific recommendations for WHIRC These strategies are a combination of common sense infrared techniques and lessons learned during the limited experience with WHIRC on WIYN and should not be taken as hard and fast rules Depending on factors such as the conditions temperature seeing clouds science fields sparse crowded or extended objects and filters broad or narrowband variations on the basic observing strategy may be desirable In the time since the article referenced above was written significant advances in infrared detector technology have transpired The 2K x 2K detector in WHIRC is comparable in size to CCDs in use the dark current is negligible and the read noise while high by CCD standards 20 e in Fowler 4 mode is sufficiently low to permit background limited operation even through most of the narrowband filters 6 1 IR Strategy in General There are two fundamental differences between optical and infrared imaging which drive the observing techniques which are used in the latter e The background from the sky is significantly larger in the infrared than in the visible In the J and H bands the background is primarily from atmospheric OH emission and in the K band thermal emission from the telescope and WTTM optics increases rapidly with wavelength As a result the sky background will usually be far larger than the astronom
53. ning if there are no suitable guide stars available for WTTM since this lets one know in advance that the IAS guider will be necessary for observing that field The NOMAD catalog available through the USNO at http www usno navy mil USNO astrometry optical IR prod icas usno icas is a useful resource Once the science field is acquired and properly centered on the WHIRC field of view the observer should pick out a suitably bright star in the image and measure the x y coordinates on the ds9 using imexam The OA can then enter those coordinates into the WTTM control which should move the error sensor probe to the proper coordinates to pick up the star Once the star is located the OA can turn on the WTTM guiding and science observations can begin As noted above the WITM probe will follow telescope motions commanded by an observing script as long as it is not requested to move outside its limits of motion WHIRC User s Manual Version 1 07 2009 May 28 51 APD Response R Magnitude vs APD Counts 20 January 2009 Contaminated Optics 1 4 variable seeing 19 February 200 Contaminated Optics 0 8 seeing January 2008 Clean Optics Is May 2008 Clean Optics 17 Faint Limit at 100Hz Sampling 40cnts per sample interval above sky R Magnitude 7 12 11 a 100 1000 10000 le 05 APD Counts cnts sec Figure 7 3 R band magnitude plotted against APD error sensor count rate obtained on several WTTM comm
54. of the array For faint sources requiring many individual observations 1 e 1f integration times are limited by background one may either use a large dither pattern 5 x 5 or repeat a small grid say 2 x 2 many times In the latter case it is good practice to offset the grids by small amounts arcsec to achieve better sampling over the array e Moderately extended targets If the source is extended but lt 1 arcmin or so one can still dither the source on the array but using spacing sufficient to ensure there is no overlap of the source on adjacent dither positions so one can still use the source observations for generating a sky frame e Very crowded fields or extended targets One will still use a grid pattern dither on the source field but 1t will also be necessary to obtain observations of a nearby but sparse field to generate the sky data See Fig 5 25 fora WHOMP script which combines a small amplitude dither on the source field with another on a sky field 6 arcmin distant Relatively small amplitude dithering on the source field will maximize the field common to all observations See section 6 2 3 on guiding strategies 6 2 2 Integration Time There are no hard and fast rules regarding appropriate integration time for a particular observation Source brightness seeing filter and observing efficiency all come into consideration In general one will want to use an integration time sufficiently long to achieve photon noise l
55. of the MOP script It may be necessary to find a guide star closer to the center of the science field 7 Based on the signal level the OA will determine an appropriate sampling frequency and activate WTTM 8 Download the appropriate MOP script and execute normally The OA will advise whether the WI TM probe is following the offsets properly 9 If observing a science field where the IAS guider is required either because of the lack of a bright guide star or a large guided offset script push the Disable WT TM button on the WTTM Client GUI and verify that the message WTTM dithers disabled appears in the MOP Status Window Fig 5 8 WHIRC User s Manual Version 1 07 2009 May 28 54
56. op right corner This action will turn off the PAN processes If the window had been minimized during observing bring it up by clicking on the VNC button on the taskbar 4 Exit the MOP by pulling down the File menu and selecting exit 5 Keep the WHIRC Engineering GUI up for temperature control and monitoring purposes NOTE Additional step if taking down the whole system 6 Take down the WHIRC Engineering GUI by clicking on the Quit button in the lower left corner of the screen NOTE Additional step if WHIRC needs to be powered down e g electrical storm or transport to town for maintenance 7 Turn off the DHE power and other WHIRC power by walking to level B of the telescope skirt and switching the power strip to the off position you will need a step ladder to reach the switch This will turn the power off to the DHE the LakeShore temperature sensors detector heater and gaussmeter sensors WHIRC User s Manual Version 1 07 2009 May 28 26 5 4 Troubleshooting Problems with MOP PAN or WHIRC bias During Startup 1 Take down all the windows as in the Shutdown procedure section 5 3 Check that no Engineering GUIs or WHIRC Bias GUIs are up shut them down if there are any 2 Single click on clear PAN button a terminal window should appear showing the clearing of the processes and then exit automatically 3 Single click on MASSIVE CLEANUP button a terminal window should appear showing the clearing of the processe
57. qual number of images with the lamp turned off for all filters in the K band to subtract from the lamp on flats The motivation is to eliminate the thermal background emitted from the warm surfaces in the optical train which are at varying distances from the instrument and most probably do not emit a uniform field of radiation We recommend taking lamp off data for all filters although darks of the same integration time are probably sufficient for the J and H narrowband filters In Table 3 2 we list the recommended settings for dome flats through the WHIRC filters These assume Fowler 1 mode and an integration time of 5 s partly to keep the process of WHIRC User s Manual Version 1 07 2009 May 28 S generating flatfields from being too time consuming but also to minimize dark current and the thermal background flux mentioned above The target signal level 1s approximately 10000 ADU Comparison of flats taken in Fowler 4 and Fowler 1 modes show them to be almost identical but we recommend a conservative approach and suggest obtaining flats for Fowler 4 science observations in Fowler 4 mode as well For Fowler 4 and an integration time of 16 s try lamp settings approximately 2 3 of those in the table Remember that Fowler 4 signals are added so the target signal level is 40000 ADU Table 3 2 Recommended Lamp Intensities for WHIRC Flats Fowler 1 5 s Fel 000 11000 Fell 4500 1000 12000 H 000 12000 Bry o 1050
58. rray center using the ruler task in the ds9 display and ask the OA to offset the telescope appropriately It 1s a good idea to take another exposure to verify that the star is now centered This can lead to problems if one does not understand the nuances of the telescope commands in the WHOMP scripts 1 The offsetScope command may use the modes set or adj The set mode will execute a telescope offset to the coordinates X and Y arcsec in RA and DEC respectively with respect to the original telescope pointing In other words these are absolute offsets and any manual offset earlier performed by the OA is disregarded The adj mode will execute a telescope offset by X and Y relative to the current telescope position WHIRC User s Manual Version 1 07 2009 May 28 40 2 As an example to execute a four position dither in a square 30 arcsec on a side with respect to the original telescope pointing one could use the sequences offsetScope set 15 15 offsetScope set 15 15 offsetScope set 15 15 offsetScope set 15 15 each followed by an observe sequence At the end the command offsetScope set 0 0 will move the telescope back to the initial position 3 If one wishes to execute the same dither script with respect to the current telescope position one would use the following sequence offsetScope adj 15 15 offsetScope adj 30 0 offsetScope adj 30 30 offsetScope adj 30 0 each followed by the observ
59. s a linux computer whirc pan which connects to the DHE and effectively runs the array and acquires the data The observer will open the connection to the PAN during startup and close during shutdown WHIRC User s Manual Version 1 07 2009 May 28 10 Figure 4 2 shows the two WHOCS subsystems of particular interest to the observer the Monsoon Observation Platform MOP which is the user interface from which the observer controls WHIRC and the WHIRC Observation Manager amp Planner WHOMP which 1s used to generate observing scripts Both will be described in later sections m j F e o i Tat a 7 i Y L F n r DI r E 7 a T tre z pli ra gt Figure 4 1 Overview of the WHIRC system architecture WHIRC Observation Control System WHOCS Figure 4 2 Overview of the WHIRC system architecture showing the interaction of the MOP and WHOMP within the WHOCS WHIRC User s Manual Version 1 07 2009 May 28 Il 5 0 Observing with WHIRC 5 1 Starting Up WHIRC from Scratch WHIRC is operated from the observer s station in the SW corner of the WIYN control room The host computer is dust The three flatscreen monitors are set up within a single display environment so that windows may be rearranged onto any of the three panels The setup procedure requires interaction between the observer and the Observing Associate OA Execute the setup commands in the order specified below You can rearrange th
60. s and then exit automatically 4 Redo the startup procedure d b e f g WHIRC Engineering GUI Observing Assistant check there are no errors Start PAN Observer wait for all four window to come up check there are no errors Start MOP Observer check there are no errors in the debug window and wait until the filter buttons turn green Start WHIRC Bias GUI and Bias detector Observing Assistant 1 Reconnect PAN 11 Update Voltages i Power Detector iv Bias Detector v Wait for OA to say when to proceed Start WHOMP Start DS9 Start PyRAF 5 Ifthe filter wheels have problems or errors have the OA do the following on the Engineering Filters screen ono Se Click Reset Gaussmeter Click Reset Wheel 1 Click Home Wheel 1 Click Reset Wheel 2 Click Home Wheel 2 WHIRC User s Manual Version 1 07 2009 May 28 27 5 5 Taking an Observation Using the MOP 1 In the MOP window set up an observation a Change to the desired filter by clicking on the appropriate filter button This action will move both filter wheels to the desired location for the filter One of the filter wheels will be in an open position and the second will be moved to the position of the filter e Monsoon Camera Co ntrol Comms Opts PAH Help target dark Exposure type Dark di ra 00 10 22 303 dec 87 27 26 778 observer Meisner Exposure Lin seconds 1 100 El Number of frames 4 Mmatadatan Sep 00
61. sec the degree of improvement was mixed Our experience with WHIRC is limited Fig 7 2 but qualitatively similar We anticipate that the improvement in native seeing at longer wavelengths combined with the larger diffraction disk may result in corrected images which approach the diffraction limit in the K band Because WHIRC is mounted on the WTTM port the light is always passing through the WTTM optics even if active correction is not being used The six additional reflections four WTTM surfaces the pickoff mirror and dichroic will affect the system throughput and more importantly increase the thermal background seen in the K band The expectation is that the improved image quality seen in the K band with active tip tilt correction will compensate for the higher background surface brightness While observers may wish to familiarize themselves with the operation of WTTM the plan is to leave the actual setup and operation of the system to the OA A separate set of WTTM GUIs from the client GUI Fig 5 9 7 4 at the observer s station will appear on the OA s terminal and be used for the guide star acquisition and WTTM activation FWHM arcsec 1 1 2 Tip Tilt Open Loop FWHM arcsec 0 5 10 15 20 25 5 10 15 20 25 30 Image Image Wed Feb 4 11 02 39 2009 Figure 7 2 Results of two tests to measure the FWHM improvements from turning on WT TM correction using 10 s exposures in the H band The results are con
62. sistent with the predicted improvements of 0 1 0 15 arcsec and even more significant when wind buffeting is a factor Courtesy C Corson and H Schweiker WHIRC User s Manual Version 1 07 2009 May 28 50 7 2 Using WTTM 7 2 1 Guide Star Selection Observers are reminded that WTTM is essentially a fast guider typically operating in the 100 150 Hz range Stars which may seem bright in a deep CCD image of a galaxy field may be too faint for WTTM guiding Figure 7 3 isa plot of the APD count rate as a function of guide star brightness on several commissioning nights Under good seeing conditions lt 0 8 arcsec FWHM one can use WTTM on guide stars as faint as 15 5 but at this limit focus drift or light clouds can cause the guider to lose the star In addition because the APD error sensor light passes through the WTTM active optics the field is limited to that of WTTM approximately 4 arcmin This is significantly smaller than the available range of the IAS guider Fig 6 1 WTTM guide star acquisition uses the coordinates of a suitable star in the WHIRC field which is only slightly smaller than the WTTM guide field so large dither patterns should not be attempted using WI TM guiding A WTTM guide star close to the center of the field increases the allowable probe motion We strongly suggest that observers locate potential guide stars for their fields prior to arriving at the telescope This is particularly important in determi
63. source onto different pixels for each integration In theory this technique can work with as few as two positions Subtracting one image from the other effectively removes the background signal as well as bias and dark current leaving positive and negative images displaced from each other However having only two measurements makes it difficult to evaluate the presence of bad or noisy pixels and the subtraction process increases the noise by V2 We generally recommend a minimum of 4 or 5 dither positions since this gives better sampling of the target image on good pixels Furthermore in sparse fields one can combine the images with a median sampling algorithm to obtain an image from which the sources are removed This sky image can then be subtracted from the original raw images to generate sky subtracted images Because the sky image is an average of several raw images the noise penalty is reduced as well For very deep observations the dither pattern is repeated many times with small differential offsets between each pattern to obtain better sampling over the detector pixels In extremely crowded fields or on extended objects subtending an appreciable fraction of the WHIRC field it is necessary to supplement the on source dithering with similar dithered observations of a nearby but sparse field to generate the sky frame While these additional observations reduce the overall duty cycle they are necessary to obtain good sky
64. ss wrtToRead generic Success Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Figure 5 12 WHIRC Detector Bias window prior to top panel and after bottom panel carrying out the Updating Voltages procedure WHIRC User s Manual Version 1 07 2009 May 28 22 c Click on the Power Detector button which should go with no errors and turn green The last two readings vdetCom and vrstUC should read the same value indicating the detector bias voltage 1s zero Tv WHIRC Detector Biasing CE Temperature 0078 501 K Voltages ok mw Power Detector JS Bras Detector Reset Temp Monitor WIYN Staff use Only Update Voltages Reconnect to PAH Sep 26 18 14 47 whire bias Sep 26 16 14 4 pan ppxGetaVP Bias Tel 16 vrstUc Sep 26 18 14 47 pan gt OK ppxGetAVP Success Sep 26 18 14 47 whirc bias check Bias Tel 16 vrstUc Sep 26 18 14 47 pon gt PpaGeLAVP Bias Tel 04 vhiRu Sep 26 18 14 47 pan gt OK ppxGetAVP Success Sep 26 18 14 47 whirc bias check Bias Tel 04 vhiRowE oK Cancel Sep 26 18 14 47 pan ppmGetaVP Bias Tel 11 vdetCo _ _ Sep 26 18 14 47 pan gt OK ppxGetAVP Success Sep 26 18 14 47 pan ppxGetAVP Bias Tel 16 vrstUc Sep 26 18 14 47 pan gt OK ppxGetaWP Success YA wrtTcRead ceneric Success Bias Tel 16 vrstUc 0 976042 lt 0x00000146 gt Sep 26 18 14 47 pan ppxGetAVP CLKO_OUTPUTEN Sep 26 18 14 47 pan gt OK ppxGetaVP Success CLKO_OUTPUTEN 0 00
65. st particularly when using WITM e A problem occurring in the middle of an extended script may make it more difficult to continue from that point e Unless conditions are very stable the focus will likely drift during the course of the observation WTTM should eventually incorporate autofocusing Observations of extended or crowded fields will generally not be able to accommodate a large guided offset to a sky field again because of the physical limitation of the guide probe motion Relatively small 10 15 arcmin offsets may be possible with the IAS probe depending on the direction and location of the guide star Fig 6 1 We are investigating having the guider turn off during scripted offsets to sky fields then resume once the telescope returns to the science field The WTTM guide field Fig 6 1 is only slightly larger than the WHIRC field of view so it can be used only for mapping small regions depending on the location of the guide star with respect to the field center Offsetting to a sky position with WTTM is likely to be impossible because of the limited range WHIRC User s Manual Version 1 07 2009 May 28 46 WIYN IAS Guide Field WTTM Deployed 840 720 600 480 360 240 120 0 120 240 360 480 600 720 840 Unvignetted Focus Probe Field cz Unvignetted Guide 480 222 Probe Field North SS Vignetted Field 240 IAS Y Axis arcsec South 720 840 720 600 480 360 240 120 0 120 240 360 480
66. t which was used to transmit a fraction of the light to the tip tilt error sensing quad detector when WTTM was employed with a CCD has been replaced by a dichroic since the quad sensor and WHIRC wavelength ranges are exclusive This increases the sensitivity of the quad sensor which now receives almost all of the optical light to R 15 5 under good seeing conditions WE ele ot ADC not used with WHIRC A intermediate WTTM Focus WTTM Pickoff Y HER A YA Mirror p n 5 gt Tilt A al Mirror m2 Pian ors Se i Dichroic LAA Taw me M3 A an mi Mini Mosaic Ht 4096x4096 CCD a WHIRC Figure 7 1 Schematic of the WTTM optical system from Claver et al 2003 The ADC prisms are not used with WHIRC The beam transmitted through the dichroic goes to the error sensor WHIRC User s Manual Version 1 07 2009 May 28 49 One should keep in mind that tip tilt correction represents the first step towards adaptive optics but it is only a first step Tip tilt correction will not miraculously produce excellent images when the seeing 1s poor although experience in the optical showed that with seeing gt 1 0 arcsec WTTM could significantly reduce the image motion The best results observed in the visible were when the native seeing was in the 0 5 0 8 arcsec range with improvement of 0 15 to 0 18 arcsec in FWHM When the seeing was excellent lt 0 45 arc
67. the image quality is good so one should be prepared to update the focus more frequently under these conditions WHIRC User s Manual Version 1 07 2009 May 28 48 7 0 WTTM Operation WHIRC is mounted on the WI TM WIYN Tip Tilt Module port of the telescope Instrument Adapter System We anticipate that the tip tilt compensation from WTTM in combination with the excellent native seeing at WIYN can result in near diffraction limited images 0 2 0 25 arcsec in the K band NOTE The commissioning of WITM for use with WHIRC is essentially complete but the steps of fully characterizing its performance and training the support personnel are still ongoing WHIRC WTIM is currently offered for use in shared risk mode in which there may be risks to observing efficiency associated with the operation of WTTM and there may be nights where WTTM is unavailable due to the lack of trained support personnel or not immediately repairable should a problem occur during the night This section of the manual will be updated as we gain experience with this system 7 1 WTTM Description A layout of the WTTM optical system 1s shown in Figure 7 1 taken from Claver et al 2003 SPIE 4837 438 to which the reader is referred for more details on the design and construction Two modifications to the original figure are relevant to operation with WHIRC First the ADC prisms are not used with WHIRC Secondly the beamsplitter in front of the WHIRC mounting por
68. uce clutter a If error messages occur on the PAN windows single click on the clear Pan button to clear out any malfunctioning processes This will close the VNC session Single click the start Pan button again b Ifthis does not clear up the problems then click the Massive Cleanup button This carries out a more comprehensive initialization of the PAN processes Two or three cycles of this may be necessary c NOTE Error messages containing fpx indicate fiber connection errors If these recur during repeated attempts to initialize the PAN there may be a hardware issue with the fiber connection between whirc pan and WHIRC iw Winter whirc pan kp no noao edu 1 mo nsoon panDaemon FDEGA panDaemon starting FDEGA panImgBufferInit create FDEGA cfglnit starting FDEGA cfgInit I attach succeed libefgCmds FDEGA cfgInit I attach pointer Oxa24dc000 FDEGA cfgInit I attach processes 0 DIEC cfgInit I initializing DIEG cfgInit ending DBC panDaemon registered 1182 new commands FDEGA panDaemon Nxt Command is 1210 FDEGA panDaemon After detInit status 0 FDEGA panChkDHEBrdIds starting DEG panControl after SockBind status 0 FDEGA Starting panProcAlg FDEGA panMemInitNotDaemon attached _panMNemP Oxb F00000 DEG panImgBufferInit create 0 FDEGA cfglnit starting DIEG cfgInit I attach succeed libcfglmds FDEGX cfglnit I attach pointer 0xa2508000 FDEG cfglnit I attach processes 2 FDEGA
69. ving script in progress WHIRC User s Manual Version 1 07 2009 May 28 37 5 7 Making an Observation Script Using the WHOMP 1 Open the WHOMP GUI to set the observing parameters for the script Below 1s an example of a small dither script for the standard star FS29 No mapping is done so Map Repeat is set to 1 and the number of mapping cells is set to 1 in both X and Y The Dither pattern is a 2x2 box with 20 arcsec separation The exposure time for each dither position is 20 s and only one cycle of dithers is done No sky only dither positions are done The shape of the dither pattern is shown as colored outlined boxes on the blue screen If you want to display the dither pattern on the 2MASS all sky survey select target on sky from the View pull down menu and the dither box pattern will appear superposed on the 2MASS image of the region this may not be currently installed NOTE The Target Name must have no spaces since it becomes the default file name vi Map Designer File Recipes View WHOMP Version 1 6 30 Nov 2007 Target Name Fss 00 Target Coordinates Heliocentric Coordinates a Ecliptic Declination gt D Paa gt Galactic Rolf op o 0000 Equinox 2000 Map Designer Number of X Cells aa of Y Cells Shape Selector 1 Grid A A Plus X Cell Spacing arcsec Y Cell Spacing arcsec 160 180 a nied mi Map Repeat 1 Sky Dither Designer Map Dither Designer X Offset deg
70. which WTTM may provide Dither sequences should be planned to accommodate relatively frequent focus updating which may be necessary if the temperature 1s changing and the image quality is good As noted above WITM may typically produce FWHM improvements on the order of 0 1 0 15 arcsec but can be much more effective in reducing the effects of wind shake on the telescope WHIRC User s Manual Version 1 07 2009 May 28 53 1 During the initial startup procedures the OA will boot up the WTTM computer load the software start the LVDT monitor for the x y stage and check APD operation 2 Go through the normal WHIRC startup sequence described in section 5 The OA may ask you at some point to push the Enable WTTM button and to ensure that the Guided dithers button 1s not active 3 When observing bright standards where guiding 1s not required the OA will have the WTTM guiding turned off 4 To observe a science field with WTTM go to the field and take an exposure ask the OA to move the telescope to center the field 1f necessary Identify the guide star in the image and use imexam to determine the x y pixel coordinates on the detector 5 The OA will enter these coordinates to send the APD probe to the position of the guide star If all goes well the APD signal will be visible on the APD Count Monitor screen at the OA terminal 6 Verify that the WI TM guide probe will be able to accommodate the telescope motions during the execution
71. xposure time sufficiently long to achieve background limited performance in a single exposure For Fowler 1 mode readnoise 35 e this means achieving a background level gt 600 ADU 2400 e This is quite easy in the Ks band and depending on the season one will probably want to pick an integration time which gives a background 10000 15000 ADU In the H band background saturation is not an issue and the integration time is a tradeoff between duty cycle and image quality and whether one is guiding or not Observers have used integration times of 100 s without noticeable image degradation under good 0 7 arcsec seeing conditions without guiding For deep observations in the J band one may wish to use Fowler 4 mode since the lower read noise gives a lower threshold gt 200 ADU for background limited operation One can then use integration times 75 100 s and achieve background limited operation with guiding observers have used 300 s integration times o Narrowband Filters One will almost always operate in Fowler 4 mode to realize the advantage of lower read noise 20 e and use long integration times 300 s or more with IAS or WTTM guiding Integration times as long as 1000 s have been used successfully Depending on the OH airglow intensity one may be background limited in 600 s in all except the Low Airglow and He I filters e General Particularly for fainter science targets aren t they all there is an element of
72. y flats has been carried out Observers are free to use sky flats except for taking darks they come for free from the observations but we recommend taking dome flats as a backup The low sky background in the J and narrowband filters generates insufficient signal for a high S N flat so sky flats in these filters will require twilight illumination WHIRC User s Manual Version 1 07 2009 May 28 47 6 2 5 Darks Unless one 1s generating sky flats from science data or twilight observations there 1s no need for dedicated dark observations with WHIRC The process of image subtraction for both science and dome flat observations also removes any dark current or fixed bias contribution from the result However we strongly recommend taking a series of 10 or 20 darks OPAQUE filter with 5 s frame time during the afternoon as a check on the noise performance This is also useful to WIYN in its program of long term monitoring of instrument performance For generating sky flats a series of 10 to 20 darks at the integration time used for the science observations 1s required 6 2 6 Focus WHIRC has no equivalent to the focus routines used with CCDs because one cannot produce multiple images at different focus values on the detector in a single exposure Rather one must take separate images at different focus values and determine the best image by inspection One will generally want to start well out of focus then step through the focus values by st
73. ys actively guiding but using the WTTM and not the IAS guide probe Section 7 NOTE Under conditions of significant wind buffeting using WTTM can produce significant improvement in image quality even for standard star or short integrations This is a clear strength of WTTM in helping overcome the inherent vulnerability of the WIYN telescope to wind shake due to the relatively light weight of the telescope and its large cross section within the dome slit An important consideration whether guiding with the IAS or WTTM is the limited physical range of the guide probe When executing a dithering script one must ensure beforehand that the guide probe will be able to follow the guide star throughout the entire range of the observation One may ask the OA where the guide probe is located with respect to its limits and if necessary select another guide star which is closer to the center of the field Carrying out a very large map with a single script is not recommended for a number of reasons particularly if using guiding e As noted above a very large map may result in driving the guide probe into a travel limit unless one has carefully set things up prior to the observation Jf the guide probe is commanded to exceed a limit it will not move and the next observation in the script will occur at the same location At best this will result in a displacement of the remainder of the script observations At worst the guide star is likely to be lo

WIYN High-Resolution Infrared Camera (WHIRC) User`s Guide

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