Home

FEROS manual

Contents

1. 4000 5000 6000 7000 8000 9000 Wavelength A Throughput Atmosphere Telescope Instrument CCD 4 Figure 2 5 The measured efficiency Empirical measurements of the efficiency of FEROS 2 20m are made according to the FEROS Cali bration Plan every night when FEROS OBs are are executed both Visitor amp Service Mode and are plotted in the graphic below Each order is joined by a line The blue line represents the theoretical expectation tabulated above The user can only affect the spectral resolution by the choice to some extent by binning the CCD The factors outside his her control which affect the resolving power are the diameters of the SCIENCE fibres the number of slices created by the image slicers 2 image quality of the optics including the focus and the alignment CCD effects chip tilt diffusion of photoelectrons charge transfer as well as the echelle dispersion The instrument does not include a remotely controlled focus adjustment since 18 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 the camera automatically compensates for temperature variations within the instrument enclosure A two slice image slicer results in a resolving power of 48 000 with a degradation less than 1096 over the whole wavelength range The individual transmission and reflection efficiency curves of the various optical components and of the CCD and the combined overall efficiencies are tabulated at http www ls
2. If FEROSUseAFDRSFITS Y then DRS products converted to FITS files according to the following convention mDPID modified DPID FEROS YYYY MM DDTHH MM ss sss i e without the fits extension The one dimensional extracted frames are r lt DPID gt 1081 fits lt gt lt NNNN gt 1 bdf r lt DPID gt 1082 fits lt gt f lt NNNN gt 2 bdf The list of other products lt DPID gt 1051 fits lt gt f lt NNNN gt ext1 bdf lt DPID gt 1052 fits lt gt f lt NNNN gt ext2 bdf lt DPID gt 1061 fits lt gt rebinned1 bdf lt DPID gt 1062 fits lt gt rebinned2 bdf HHH H 52 Appendix D Data Archiving FEROS SCIENCE data are archived in the ESO data archive automatically according to the ESO VLT Data Flow System Specifically for FEROS the NGAST system originally installed for the WEI instrument at the MPG ESO 2 20m telescope is used In anycase since the data are in the ESO archive they can be accessed via the standard tools see http archive eso org FEROS data have been ingested into the ESO Science Archive since the FEROS big bang i e the upgrade to VLT compatibility which was made in November 2003 In addition data since August 31st 2001 has been archived on CD and is maintained by La Silla Science Operations Access to this archive is limited and depends on the availability of La Silla SciOps staff Enquiries should be addressed to the La Silla SciOps Shift Leader lasilla eso org Data Packages for
3. 0 0 0 0 000 eee eee L3 Capabilities al the Instrument s lt uoa loea o 44 xoxo or Wow Eo e L FEROS within ESO 2x um Gu ege cnc oomen ov XO x X xw x ox o8 LI Le HA ie as aaia xoxo x3 a S ER 84 ue SUEDE 3 x ed WA Jaranal ou gon wk ok ees E Eom te eS A Rea Gs GO ER an Be 1 5 How to access FEROS sample calibrations and observations LE BIbUOBRESDUN a s encia n ok eo Re Ree de AUR RR UR OR en LT AREA S n 26 Qoo ek a RO Ew Da ES 4o ME A Eee 1 8 Abbreviations and Acronyms Instrument Characteristics 2 1 QOptoanechanicallayout so se scs xo o naar ee Y RR Rs 2 2 Tnstrument subsystems 2e s e po oA RR Re Ae XO Ren 2 2 1 The pre fibrehead system a 2 2 2 Whe e 2 3 The Fibrehead Viewer COD 4 21 2569 oy 9o Loy E EORR 9 y eos 2 4 The Scientific CCDs and the associated shutters a 25 The FEROS Calibration Unit sona a roto om 9 m ot R9 om m 20 FEROS WFI Adapter 2 999 kde 6446446 60 re badug EEG SEGA 2 7 Spectral Coverage Resolution and Overall Efficiency lll 2 8 Instrument Features and Problems to beawareof 22s 2 8 1 Interference fringes in Internal Flatfields o 2 8 2 Contamination of Object spectrum by ThArNe source in OBJCAL mode 2543 Dir gal DAVON v eh a E e eek WE ROME E SIE Get xl eoe UO pS 2 844 Biem dal COD RON zuo bk ee ee ole Rx Wok oe e AR 3e 3 deus 2 85 Low flux level in bluest orders in Flatfields l
4. instrument and detector Mode Selector Unit in the pre fibrehead area of FEROS which can direct calibration light into one of the fibres Observation Block A logical unit of exposures needed to obtain a coherent set of data Encom passes all relevant information for a successful data acquisition on a target It consists of target information a set of templates parameter files for the templates conditions requirements and comments concerning the specified observations It represents the entity the short term sched uler deals with Constructing Observation Blocks is part of the Phase II Proposal Preparation Process Phase II Proposal Preparation P2PP During this phase the successful applicant whose Phase I proposal has been accepted based on the scientific rationale and technical feasibility prepares the Observation Blocks to carry out the observing program Standard Setting A pre defined setting of the instrument facilitating the preparation of the observations The Observatory keeps an updated database of the relevant calibration files for all Standard Settings of the instrument Template A set of instructions for the performance of a standard operation on an instrument typ ically an instrument and detector setups The templates represent specially devised sequences for all instrument operations and calibrations Template Signature File This is a description of a Template and its parameters It contains information about th
5. 0 000000 14 43 TEMPS 4 14 570000 14 563333 14 560000 1 NX cV cV cV cV o aS sx Os V o D V gt Ns sos FEROS WFI sel mirror name Instrument mode used Optical path used sensor ID Maximum value Average value Minimum value sensor RMS of Sensor common name samples over exposure numeric value ID common name sensor sensor Sensor numeric value FCU shutter unique ID FCU shutter name FCU shutter number If T function is software simulat FCU shutter element Software simulation Temperature sensor ID Maximum value C Average value C Minimum value C Temperature sensor name RMS of samples over exposure Temperature sensor numeric value Temperature sensor ID Maximum value C Average value C Minimum value C Temperature sensor name RMS of samples over exposure Temperature sensor numeric value Temperature sensor ID Maximum value C Average value C Minimum value C Temperature sensor name RMS of samples over exposure Temperature sensor numeric value Temperature sensor ID Maximum value C Average value C Minimum value C Temperature sensor name RMS of samples over exposure Temperature sensor numeric value Temperature sensor ID Maximum value C Average value C Minimum value C 58 HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HI
6. It includes a mirror M3 mounted on an arm which moves in and out of the beam to select between FEROS mirror IN beam and WFI mirror OUT of beam With M3 in the telescope beam is reflected onto the downward facing fibrehead which is a polished solid aluminium block The SCIENCE fibres are mounted into the back of the fibrehead and are illuminated via the fibrehead apertures holes 2 0 arcsec in diameter on the sky separated by 2 9 arcmins oriented EW of each other in the default orientation of the telescope rotator The FWA also includes the Sliding Calibration Selector Mirror SCSM which is used to control which of the SCIENCE fibres is illuminated by light from the CALIBRATION fibres whose exit is also mounted in the Adapter and the Atmospheric Dispersion Corrector which was installed and commissioned during March 2005 A new ADC was later installed in April 2006 The Spectrograph itself is installed in a thermally stabilised room the FEROS Climate Controlled Room CCR located on the level below the observing floor in the 2 20 m telescope building within the so called FEROS Room The optical components are mounted on an 2400 x 1500 x 200 mm Newport M RPR 58 8 optical table There are no movable or remotely controlled components on the optical table except the CCD shutter and the LED CCDTest light ring which can be moved manually and whose three sets of LEDS Red Green amp Blue can be remotely turned on and off Therefore FEROS works
7. April 2006 The dashed line indicates the 90 transmission level provide a much improved optical matching between telescope and fibres An important improvement being that the effective aperture with the new rod lenses is restored to the design specification of 2 0 arcsec as compared to 1 6arcsec which was the case for the ball lenses The rod lenses thus improve the overall efficiency as well as increasing the throughput as a function of seeing image quality The SCIENCE fibres are of 100 um diameter FV type each measuring approximately 15m in length The current fibres were installed during October 2003 at the same time as the new microlenses replacing the original fibres from the ESO 1 52 m which were also of type FV The main reason for replacing the fibres was to increase the length in order to be able to reduce Focal Ratio Degradation due to stress on the fibres caused by small radius curves necessitated by the less than ideal length of the original fibres The SCIENCE fibres are interfaced to the microlenses using optical glue The intrinsic efficiency ratio between the designated OBJECT and SKY fibres is between 1 6 in the blue and 1 3 in the red varying smoothly between these two extreme values see figure 2 3 The F N Adaption Lens System TBD See the original FEROS Final Design Report downloadable from 12 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Fiber Efficiencu Ratio 4000 6000 8000 Wavelength F
8. De tector Team for additional general information on the CCDs and the Control System FIERA http www eso org odt 16 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 2 5 The FEROS Calibration Unit The FEROS Calibration Unit FCU provides flat field and wavelength calibration lamp sources to the spectrograph Light is delivered from the FCU via the Calibration fibres to the adapter where optics image the light onto the fibrehead reproducing the illumination of the pupil of the telescope From the fibrehead the light is then delivered to the spectrograph via the Science fibres see figure 2 1 The FCU currently houses three sources e LAMP1 Wavelength Calibration ThArNe This source consists of a single Thorium cathode Argon 10 and Neon 90 filled Juniper lamp e LAMP2 Flat Field Hal Hal This source consists of two Halogen bulbs one 6V 10 W Osram Halogen Halo Star bulb providing the red part of the flatfield and one 12V 50W Osram Halogen Xenophot bulb behind a blue filter providing the blue part of the flatfield Light from the two bulbs are combined via a 50 transmission 50 reflection mirror e LAMP3 Wavelength Calibration ThAr Ne This source consists of a Thorium cath ode Argon 100 filled Juniper lamp and a 100kQ 220V Neon bulb Light from the two bulbs are combined via a 50 transmission 50 reflection mirror Prior to June 2003 only the ThAr Ne source was available Between June 2003 and December 2004 on
9. ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS INS MIRR3 MODE PATH SENS7 SENS7 SENS7 SENS7 SENS7 SENS7 SENS7 SENS8 SENS8 SENS8 SHUT1 SHUT1 SHUT1 SHUT1 SHUT1 SWSIM TEMP 1 TEMP 1 TEMP 1 TEMP 1 TEMP 1 TEMP 1 TEMP 1 TEMP2 TEMP2 TEMP2 TEMP2 TEMP2 TEMP2 TEMP2 TEMP3 TEMP3 TEMP3 TEMP3 TEMP3 TEMP3 TEMP3 TEMP4 TEMP4 TEMP4 TEMP4 TEMP4 TEMP4 TEMP4 TEMP5 TEMP5 TEMP5 TEMP5 NAME ID MAX MEAN MIN NAME RMS VAL ID NAME VAL ID NAME NO SWSIM TYPE ID MAX MEAN MIN NAME RMS VAL ID MAX MEAN MIN NAME RMS VAL ID MAX MEAN MIN NAME RMS VAL ID MAX MEAN MIN NAME RMS VAL ID MAX MEAN MIN gt FEROS gt FEROS S DEFAULT HUMI 13 450000 13 446667 13 440000 Humidity 0 004714 13 450000 gt LNLV LN level 63 440000 gt DARK DARK 4 H e TAG FAT TR RR TSR FS OSG OS TE TS Se Nia SS FREE i NORMAL TEMP1 14 430000 14 430000 14 430000 Temperature 0 000000 14 42 gt TEMP2 j 14 480000 14 480000 14 480000 Temperature 0 000000 14 48 gt TEMP3 j 14 790000 14 783333 14 770000 Temperature 0 009428 14 79 gt TEMP4 14 430000 14 430000 14 430000 Temperature
10. a well exposed smooth continuum spectra from approx imately 380 nm to 650 nm within reasonably short exposure times see Table 4 2 Below 380 nm peak S N in individual flatfield exposures at the center of the blaze function of each order falls rapidly to 50 in the bluest order The flatfield spectra provide a good correction of the blaze function of the echelle They are also useful to correct for the pixel to pixel variation in CCD sensitivity as a function of the impinging wavelength of the light and to correct for the structures introduced by imperfections of the fibre geometry fibre function The same cautions regarding stability depending on air pressure and temperature mentioned for the wavelength calibration in section 4 3 also apply to flatfields Internal flatfield exposures can also be attached to science OBs as could dome flatfields however the overhead for dome flatfields is prohibitive Peak S N in individual flatfield exposures at the center of the blaze function of each order of 500 or more Orders 35 to 58 Orders 59 to 63 5Equivalent to the slit function of conventional spectrographs 32 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 4 5 Solar spectra As per the FEROS Calibration Plan every afternoon weather permitting i e if not too cloudy approximately 1 hr before sunset four one minute solar spectra are acquired two spectra with ADC OUT and two with ADC IN 4 6 Flux standard star obse
11. command loadccd_cat image cat If the option argument image cat is omitted loadccd_cat creates a new catalogue with filename locdccd cat containing all fero NNNN mt files in the MIDAS working directory and then processes all of these This standard reduction is controlled by the FEROS context keywords which can be listed together with their current contents by the command SHOW FEROS and are set with the command SET FEROS key value See below for useful keywords to be used during the observing session A 3 Startup of MIDAS Normally the entire observer s enviromnent including the MIDAS session where the FEROS DRS pipeline will be run during the night is started up by the TIO during the daily instruments and telescope startup procedure If a something goes wrong during the night and the MIDAS session or anything else is lost ask the TIO or support astronomer to restart it A 4 Initialization of the DRS at the beginning of the night To use the automatic data reduction as described above the DRS has to be initialized at the beginning of the night For this purpose several flatfield and wavelength calibration exposures have to be taken in the Object Sky mode of FEROS before the beginning of the night This is normally taken care of each afternoon by the TIO and or support astronomer according the the FEROS Calibration Plan and is achieved via the execution of one of the Standard Calibration OBs If a visiting astronomer w
12. corresponding xcorall program the following steps are necessary e initialize the DRS as described above in the Object Sky mode The calibration exposure has to be flatfielded with the command UNBLAZ FERO ThAr thar ext FF flat ext f thar ext where thar flat correspond to the 4 digit numbers of the intialization frames of the night e observe the object in Object Calibration mode and let the on line DRS reduce the spectrum as usual Make sure that the EXT MODE S is used e Use afterwards the crosscorrelation program xcorall table object objectref thar tharref hbin action where table is a name for the table with the results the results from subsequent calls of the program will be appended to the table object objectref thar tharref refer to the 4 digit numbers of the files described above With hbin the size of the histogram bins to be used for the final determination of the radial velocity defaulted to 0 150 km s If the program is called the very first time action should be set to create to add the results from new reductions action has to be set to enter e The results can be plotted over the modified julian date MJD with the command plot table table jd24 dbc 5 Example for the first reference night Midas 11 UNBLAZ FERO ThAri200ext FF1202ext f1200ext Midas 12 00 xcorall 51Peg 1212 1212 1200 1200 create Midas 13 00 xcorall 51Peg 1212 1212 1200 1200 enter For an observation f
13. end deg ADC mode Telescope right ascension deg If T function is software simulat Telescope desclination deg Position angle at end deg ADC mode Telescope right ascension deg If T function is software simulat ADC arm position name Sliding cal sel mirror unique ID Sliding cal sel mirror name Sliding cal sel mirror number Sliding cal sel mirror element Rotating sel mirror unique ID Rotating sel mirror name Rotating sel mirror number Rotating sel mirror element Instrument release date yyyy mm d FEROS_ICS 1 5 Data dictionary for Absolute position Enc NDFW Position density Instrument ID T If T function is software simulat FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 57 HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO
14. in a fixed configuration in order to guarantee the best possible long term stability of the spectrograph The FEROS Calibration Unit FCU is located in the FEROS room It provides flat field and wavelength calibration lamp sources to the spectrograph Light is delivered from the FCU via the CALIBRATION fibres to the FWA where optics image the light onto the fibrehead reproducing the illumination of the pupil of the telescope From the fibrehead the light is then delivered to the spectrograph via the SCIENCE fibres see figure 2 1 Temperature stability of 0 5 degree celcius is maintained FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 9 Calibration Fibres Science Fibres FCU Adapter FEROS Figure 2 1 Light path of Calibrations All changes between the operational modes are carried out with at the FCU and in the FWA The prism cross dispersed two slice folded optical path results in a compact physical layout The spectrograph operates in a quasi Littrow mode in a white pupil configuration Baranne 1972 ESO Cern Conference on Large Telescopes The chelle grating is of type R2 with 79 lines mm and a measured blaze angle of 63 24 The camera is dioptric no central obstruction and provides an external focal plane for easy detector interfacing and upgrading during the lifetime of the instrument together with a large field good image quality and high optical transmission The CCD detector format is 2048
15. rebinning Saved to ThAr lt NNNN gt _LINE1 tbl by SAVE FEROS ThAr lt NNNN gt Format MIDAS table Filename ThAr lt NNNN gt lines2 bdf Keyword LINE POS TBL Content Table with found calibration lines of sky fibre order by order dispersion coeffi cients are stored in the descriptor DCOEF D 1 195 with 5 polynomial coefficients per order used for rebinning Saved to ThAr lt NNNN gt _LINE2 tbl by SAVE FEROS ThAr lt NNNN gt Format MIDAS table Filename ThAr lt NNNN gt _INIT bdf Content Table with session keywords in descriptors session keywords and defaults in table rows Session keywords are restored by command INIT FEROS MIDAS Table Filename template bdf Content Image with cross correlation template for order definition Copied to ThAr lt NNNN gt _TEMPLA by command INIT FEROS ThAr lt NNNN gt Format pixels template must be centered to central pixel FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 49 e Filename echpos tbl Keyword GUESS_TBL Content Table with guess for order definition Copied to ThAr lt NNNN gt _GORDER tbl by command INIT FEROS ThAr lt NNNN gt Format MIDAS Table e Filename centers tbl Keyword CENTER_TBL Content Table with order definition Copied to ThAr lt NNNN gt by command INIT FEROS Format MIDAS table e Filename cop coeffs1 tbl Keyword COEF COP Content Table with cross order profile definition of object fibre Copied to ThAr lt NNNN gt _COP1 tb by command INIT FERO
16. so that the target will always appear close to the center of the FFHV images displayed on the WS panel or if the telescope Coordinate Correction has been previously made with a target on the fibre then very close to if not well centered on the fibre The visiting astronomer has to validate the target identification on the image This is particularly important if the field has other close by objects of similar magnitude Note that if the target is invisible to the limit of the FFHV camera e g an emission line nebula it is possible to define in the OB a blind offset from a nearby visible star The coordinates of the science target have to be entered in the target description In the acquisition template of the OB the offsets to the guidestar have to be entered in arcseconds target coordinates offsets acquisition star coordinates Whatever the acquisition procedure once the instrument operator signals that the target is centered on the fibre the exposure is started The tracking of the telescope is corrected for errors by the autoguiding usually using guiding on fibre in the FFHV 5 2 2 Monitoring the integration There is unfortunately no facility to monitor the development of the observation no flux meter for example The observer must instead rely on the experience of the TIO at first and later their own experience based on watching the image quality in the FFHV 5 2 3 Evaluation of the results off line data analysis At t
17. the Cross Dispersing Prism through the Camera before finally arriving at the CCD The spectrograph functions and components The fibre head consists of a polished block of Aluminium The polished surface is curved in order to provide uniform focus across the field of view of the fibrehead in the fibrehead viewer The fibres are mounted into the fibrehead via brass inserts which hold the microlenses and fibres in place The microlenses are rod type lenses with a MgF Anti Reflection coating The microlenses re focus the f 8 input beam to f 4 6 as required by the spectrograph design The current microlenses were installed during October 2003 They replaced the former spherical lenses which were installed when FEROS was first moved from the ESO 1 52 m to the 2 20 m during October 2002 The microlenses used in the ESO 1 52 m fibrehead were rod lenses and indeed rod lenses were the preferred design for the 2 20 m fibrehead but at the time of moving FEROS to the 2 20m a manufacturer capable of fabricating lenses to the required specifications could not be found A company capable of fabricating the required rod lenses was subsequently discovered As compared to the ball lenses the rod lenses Telescope pointed 30 degrees from the sun FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 11 Transmission 4000 5000 8006 7000 8000 Wavelength AA Figure 2 2 The red line represents the transmission curve of the new FEROS ADC commissionned in
18. x 4096 pixels The direction of the spectral dispersion echelle orders is along the shorter dimension of the CCD The instrument spectral format wavelength coverage etc is always computed for this fixed CCD window setting 2 2 Instrument subsystems This section describes the FEROS subsystems in the order they are encountered along the optical path going from the telescope to the instrument detector The functionalities of the different subunits are explained and reference is made to their measured performance Efficiencies e g in the form of tabulated data of the main instrument components including the CCD are available from the FEROS Instrument Efficiency page from the FEROS Home page or directly at http www ls eso org lasilla sciops 2p2 E2p2M FEROS InstrumentCharacteristics InstrumentEfficiency html 2Quasi Littrow mode i e with the angle of incidence and diffraction equal but in a different plane to maximize efficiency 10 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 2 2 1 The pre fibrehead system The light path Light from the telescope arrives at the FWA M3 where it is reflected upward passing through the ADC if IN to the fibrehead The fibrehead viewing camera is located directly below the fibrehead Light from the FCU arrives at the FWA via the CALIBRATION fibres It is reflected onto the fibrehead via the SCSM The SCSM and the ADC can NOT be used simultaneously The pre fibrehead functions I
19. 4000 A and wavelenghts greater than 6000 A are completely Clear sky and seeing 1 1 2 arcsec FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 19 irrelevant Note there is still no clear way to control the flux level to be achieved except by adjusting the exposure time directly This means if we need to change the lamp sources during the period exposure levels are liable to change and OBs may need to be adjusted Currently for the Calibration Plan we make ThAr Ne and ThArNe exposures of 3 15 amp 30sec Sam ple calibration images which users could use to check flux levels etc are now available for download from http www ls eso org lasilla sciops 2p2 E2p2M FEROS ImageDB index html or by following the Data Archive and Sample Images link at the bottom right of the FEROS home page Solution Use the ThAr Ne source ThAr Ne in p2pp for OBJCAL mode observations 2 8 3 Flux calibration Due to the comparable size of the Fibre apertures 2arcsec and the typical image quality FWHM larcsec one can never be certain of the fraction of light going down the fibre and hence an AB SOLUTE flux calibration is practically impossible Currently there NO way we can be sure of this Note that the DIMM can NOT be relied upon for this information as the seeing measured by the DIMM is not necessarily and in practice almost never the same as the seeing measured at the 2 20m Therefore the best one can hope for is to get the SHAPE of th
20. 6 1404 4096 1349 1400 0608 4096 1350 1401 0000 4096 Chapter 3 Preparing the Observations 3 1 Introduction Before the actual execution of observations several steps have to be taken The preparation of an observing program is split in two parts Phase I and Phase II In Phase I the emphasis in the ap plication for ESO observing time is put on the scientific justification and on the technical feasibility of the proposed observations In Phase II the successful applicants prepare the detailed instrument set up and observing plan through the completion of so called Observation Blocks Together with the Phase I and Phase II documentation http www eso org observing proposals the infor mation contained in this chapter and in Chapter 4 provides a guideline for the Phase I and Phase II preparation process for FEROS observations In Chapter 5 information is given for astronomers who come to La Silla to observe with FEROS The preparation process for FEROS programmes can be summarized as follows Phase I e Definition of scientific justification e Choice of instrument mode e Estimate of exposure time to reach the needed S N ratio Estimate of telescope and instrument overheads e Determination of scheduling constraints e g visibility time critical observations e Overview observation plan e g target list calibration needs Phase II for successful applicants e Identification of detailed instrument set ups e Iden
21. 6 at 600 nm 78 at 700 nm 5596 at 800 nm 2896 at 900 nm Number of pixels 2048 x 4096 Pixel size 15 um Gain low 3 2 e ADU high 1 0e7 ADU Read out noise fast readout low gain 5 1 e 16 3 ADU rms slow read out high gain 3 0 e 3 0 ADU rms Saturation low gain 40 000 ADU high gain 65 000 ADU Full frame readout s low gain unbinned 41 high gain unbinned 148 Dark current levels TBD Fringing amplitude TBD CTE TBD Read out direction in disp dir Prescan Overscan areas Pix 49 0 and 2049 2098 Flatness TBD FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 15 Calibration Fibres Thare FCU Figure 2 4 Schematic diagram of the FCU The cosmetic quality of the scientific CCD is good Details are given in section 2 8 7 The CCD cryostat is not attached to the dioptric camera but is mounted independently of the camera directly onto the optical bench A rubber seal between the shutter and the CCD provides light protection The CCD is operated at a temperature of 139 K 120 L liquid nitrogen tanks ensure continuous operation without manual intervention for 2 weeks The shutter is located between the cryo stat window and the camera It is actuated by a metallic cable with an open close time of 50 ms The illumination of the detectors is homogeneous within 50 ms but a minimum exposure time of 0 5 sec is recommended The reader is referred to the CCD webpages of the ESO Optical
22. An automatic fibre positioning unit is installed at the Nasmyth focal plane It can use up to 132 fibers in the field of view of 25 arcminutes in diameter The fibers feed the GIRAFFE long slit spectrograph mounted on the Nasmyth platform The data are collected by a 2048 x 4096 pixels CCD One CCD frame contains the linear spectra of up to 132 objects observed in parallel with a limiting resolving power of 20 000 and a spectral coverage in a single exposure of 26 60 nm depending on the wavelength GIRAFFE is on average 30 less efficient than UVES but the multiplexing gain can make it the best choice if the observing program includes many objects in a single field at intermediate spectral resolution Spectroscopy at infrared wavelengths 1 5 um Complementary spectroscopic observations at infrared wavelengths can be obtained with two other VLT instruments e The infrared imager spectrometer ISAAC can be used to obtain spectra in the 1 5 um spectral region Two separate cameras in the same cryogenic vacuum vessel are optimized separately for the 1 2 5 wm and 2 5 5 wm spectral ranges with resolving power up to 10 000 if a 0 5 arcsec slit is used e A high resolution infrared spectrometer CRIRES is currently under study It is intended to be the counterpart of UVES in the 1 5 micron spectral region providing a resolution up to 40 000 0 5 arcsec slit in a single order or cross dispersed format 1 5 How to access FEROS sample calibrations and obs
23. As shown in the transmission is above 90 96 for most of the wavelength range Therefore the use of the ADC is highly recommended at airmass higher than 1 2 It is also important to remind that the ADC provides a spectral flux shape independant of zenith distance Hence for any work where the spectral flux shape is important the ADC is a must 2 8 Instrument Features and Problems to be aware of 2 8 1 Interference fringes in Internal Flatfields The internal flatfields show interference fringes for wavelengths above approximately 6550 i e Order number 30 m 34 See http www ls eso org lasilla sciops 2p2 E2p2M FEROS InstrumentCharacteristics FF rderByOrder html These fringes are stable with telescope pointing so presumably result from reflections internal to the spectrograph camera or most probably the CCD itself Solution The internal flatfields correct well for these fringes 2 8 2 Contamination of Object spectrum by ThArNe source in OBJCAL mode A number of very bright emission lines in the red part of the spectrum of the ThArNe source the source labelled WLC in p2pp templates saturate so badly that they have substantial bleeding and actually bleed into the pixels of the other fibre This is a particular problem for the OBJCAL mode because the bleeding thus contaminates the stellar spectrum The only occassion in which the ThArNe source WLC in p2pp should be used is if the spectral region of interest is wavelengths less than
24. Block that is used to perform the required observation The preparation and editing of Observation Blocks is done with the Phase II proposal preparation software P2PP 2 which successful applicants for observing time can obtain from ESO http www eso org observing p2pp for installation at the astronomer s home institute This Implemented during March 2005 and updated in March 2006 24 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 software is also available on the offline computing facilities as well as at the observer s station at the Observatory for preparation of the OBs in advance of the observations 3 4 The FEROS Exposure Time calculator The FEROS Exposure Time Calculator ETC is accessible from the FEROS web pages The ETC models the instrument and detector It is the basic tool for an observer in the planning of an FEROS observation It can be used to compute S N to be expected for the specified target and atmospheric conditions as a function of exposure time 3 4 1 Definition of the target For the input flux distribution to the ETC four options can be selected 1 A blackbody energy distribution at a given temperature 2 a power law distribution 3 a template spectrum stellar spectra from spectral type O5 to M2 nebular spectra galaxy spectra or a quasar spectrum 4 a single line at a wavelength width and flux level to be specified In all cases but point 4 the object magnitude in a given broad b
25. ERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 OBS OBS OBS OBS OBS OBS OBS OBS OBS OBS OCS TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEL TEMP5 NAME Temperature 5 Temperature sensor name TEMP5 RMS 0 004714 RMS of samples over exposure TEMP5 VAL 14 57 Temperature sensor numeric value TEMP6 ID TEMP6 Temperature sensor ID TEMP6 MAX 16 750000 Maximum value C TEMP6 MEAN 16 723333 Average value C TEMP6 MIN 16 710000 Minimum value C TEMP6 NAME Temperature 6 Temperature sensor name TEMP6 RMS 0 018856 RMS of samples over exposure TEMP6 VAL 16 75 Temperature sensor numeric value DID ESO VLT DIC OBS OBS Dict
26. ERR 119 9999 53194 89131245 2004 07 08T21 23 29 77003 397 42545 347 UNKNOWN UNKNOWN PIXEL g PIXEL g 1 0 1 0 51 0 1 0 1 0 1 0 F HIERARCH ESO ADA POSANG 381 Original 395 Standard FITS format NOST 100 0 of bits storing pix values of axes in frame pixels axis pixels axis Number of parameters per group Number of groups pixel FITS BSCALE BZERO pixel FITS BSCALE BZERO European Southern Observatory UT date when this file was written ESO Telescope Name Instrument used target 12 59 59 8 RA J2000 at start in deg 29 59 59 9 DEC J2000 at start in d Standard FK5 years Coordinate reference frame Total integration time MJD start 2004 07 08T21 23 29 396 Date of observation 21 23 23 397 UTC at start sec 11 49 05 347 LST at start sec PI COI name Name of observer OFF Pixel Pixel value coordinate system coordinate system of ref pixel of ref pixel Ref pixel of center of rotation Ref pixel of center of rotation Binning factor Binning factor Extension may be present Status of autoguider value 0 90000 Position angle at start 54 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 55 HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIE
27. EUROPEAN SOUTHERN OBSERVATORY Organisation Europ enne pour des Recherches Astronomiques dans l H misph re Austral Europ ische Organisation f r astronomische Forschung in der s dlichen Hemisphare LA SILLA OBSERVATORY Science Operations FEROS II Uses Manual Doc No 2P2 MAN ESO 90100 0008 Issue 78 0 Date 15 10 2006 Keywords FEROS II User Manual Prepared ee as oe ictor Mn Name Date Signature A 0 Schuez B Conn L Monaco F Selman DDIOUBd EASE ae AS O AO Name Date Signature Released A agn 15 10 2006 GER Name Date Signature ii FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 This page was intentionally left blank FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 ill Change Record Issue Rev Date Section Parag affected Reason Initiation Documents Remarks 1 1 1 20 07 2003 All Version 1 1 in new format 1 2 20 07 2003 All First step toward V 2 0 1 3 20 07 2003 All Removed old irrelevant text 1 4 July 2004 All Completely revised 1 5 March Nov 2005 All Updates and gap filling 77 0 25 11 2005 All Implementation of reviewer s comments 1 6 16 07 2006 All Revised version New ADC efficiency curves iv FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 This page was intentionally left blank Contents 1 Introduction 11 On the contents of the FEROS User Manual 0 000000 1 2 Information available outside this manual
28. FEROS DRS user procedures as provided by any standard MIDAS installation do not know how to cope with these changes The version of these procedures provided at the La Silla FEROS DRS web pages see above is specifically intended to be able to cope with data from all epochs of FEROS s history from the original BIAS system installed at the ESO 1 52 m telescope to the slightly modified BIAS system as originally installed at the MPG ESO 2 20m telescope to the current FIERA based system A 2 As run at the telescope FEROS images are delivered to the offline workstation w2p2off via the VLT Data Flow System The data arrive into the directory data raw lt yyyy mm dd gt According to standard practice at the Tn order to achieve VLT standard DICB compliance 39 40 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 MPG ESO 2 20m telescope the they are written with their INS file names i e FEROS ech obs objsky NNNN fits FEROS ech cal flat NNNN fits etc There is also a softlink made in the directory data backlog lt yyyy mm dd with the VLT DP ID filename i e FEROS yyyy mm ddThh mm ss sss fits pointing at the original file in data raw lt yyyy mm dd gt Two bash shell script daemon like process handle queuing these images for reduction ferosQueueIms and submitting queued images to the MIDAS DRS session ferosReduceQueuedIms Part of this process is the creation of a softlink with file name format fero lt NNNN gt mt po
29. MIRR2 CALMIRR2 CALMIRR2 DATE DID FILT1 ENC FILT1 POS ID LAMP3 SWSIM DEC END MODE RA SWSIM DEC END MODE RA ID NO ID NO NAME TYPE NAME TYPE 2000 06 16 ESO VLT DIC Normal CCD sw operational mode 1 0 Interval between two successive te 2 of sources active 138 40 Telemetry value CCD CCD Cold Plate Description 138 40 Telemetry value 140 20 Telemetry value CCD2 at read completion ID of telemetry sensor of telemetry param at read start at read completion ID of telemetry sensor COD Cold Plate2 Description of telemetry para 140 20 1 1 119 999936 120 0091 1 2148 4096 T 1 1 120 000000 1 SCIENCE ECHELLE OBJ SKY 0 00000 0 0000 OFF 0 000000 T 0 00000 0 0000 OFF S 0 000000 T gt OUT gt PARK gt PARK gt FREE a gt LAMP 1 2 gt LAMP 1 d 2 gt LAMP d 1932 0 000 FEROS 1 56 SAR OS OT RR ER aa RU RUSO eR MI e ER ER T D D BR RR s Telemetry value at read start Binning factor along X Binning factor along Y actual subintegration time Dark current time of subintegrations of pixels along X of pixels along Y If T window enabled Lower left pixel in X Lower left pixel in Y user defined subintegration time of windows readout Observation category Observation technique Observation type Telescope desclination deg Position angle at
30. OBS 004 5 2 Durme the night saos sor ca ase Be eee EIN eae WO a a Ge a SO Ronda ud Target eut 2n n xus Roe e mde mode Ge Be GE a Qe ee Sa we RR e 5 2 2 Monitoring the integrati n lll 5 2 3 Evaluation of the results off line data analysis The reduction of FEROS data 6 1 Real Time Display and quick look 2 425 sede a eR RE 6 2 Pipeline reduction of FEROS data ee 6 9 OfFline data eduction 6 2e ok n9 Ry RR a how e RR RT Other useful information Ti List Gi Stannard Shares 99x ecd X eR XC Yo RCRUM A L2 baste QI Gre lines escasa sU EGER Rex aah wh echte m See he e en RR ter edd 7 3 Pointers to FEROS sample observations osoo a Using the DRS pipeline at the telescope Ai Instale db DOME cio s vor ea X Ua Sexo XO Y eq A PORRO ee ees A2 Asam ab the telescepe oscar sedo eU CR e dh cv ee es A3 Starbupor MIDAS Lu ue ee RS Oe RA dhe ee a Rob ere E A A Initialization of the DRS at the beginning of the night A 5 On line Reduction Options During the Night 0 AO GUEY protams o sx ee d acio ga mcer m xo AA A are ed AGB BOLOS nicas ae psp eho Gece amp ge Ue GR E Gm ENTE e A 6 2 Plot of temperatures ENEE piaua ENN eR Ro RERO a A 6 8 Sigmal to Noise Ratio cocep 6b ko omo RO E E eS AGA Spectrograph focus test 2 22e s Reo e Reg S e AGS System efBeleney test 6 hok oso E os A RO n xq oye dere A 6 6 Radial Velocities b
31. RARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET BITS CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIP1 CHIPS DATE DEC DID DATE ID INDEX NAME NX NY PSZX PSZY XGAP YGAP EXP NO EXP RDTTIME EXP TYPE EXP XFERTIM FRAM FRAM ID NAME OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 OUT1 ID TYPE CHIP CONAD GAIN ID INDEX NAME NX NY OVSCX OVSCY PRSCX PRSCY RON X Y OUTPUTS OUTREF RA READ READ READ READ SHUT SHUT SHUT SHUT CLOCK MODE NFRAM SPEED ID TMCLOS TMOPEN TYPE 16 Bits per pixel readout 03 10 03 Date of installat
32. ROS Documentation fdr ps gz 2 3 The Fibrehead Viewer CCD FEROS includes two CCD systems the FEROS FibreHead Viewer FFHV technical CCD and the scientific CCD detector The fibrehead viewer unit incorporates Peltier cooled 288 x 385 224m pixel frame transfer front illuminated CCDs on which an image of the fibrehead plane is focussed with a scale of approximately 0 5 arcsec pixel The unvignetted field is approximately 4 x 6 arcmin square NS EW A Johnson V filter is permanently mounted between the fibrehead and the TCCD The objective is focussed on the surface of the fibrehead It is used to identify the target to center it on the fibre aperture and for guiding both on the object on the fibre default or on a field star when not possible to guide on the object on the fibre e g due to a close i e within 5 arcsec field star The limiting magnitudes of the FFHV cameras for target acquisition are a function of seeing color of the target and sky brightness As an example with a 5 sec integration 1 arcsec FWHM seeing and dark sky an object with m V 17 is detected with adequate S N for acquisition and guiding The FFHV camera is generally able to acquire all objects for which spectroscopic observations can be made If the target is too faint to be visible on the FFHV blind offset procedures from a nearby star are provided cf Ref 1 2 4 The Scientific CCDs and the associated shutters A summary of the properties of the scienti
33. S ThAr lt NNNN gt Format MIDAS Table e Filename cop coeffs2 tbl COEF_COP Content Table with cross order profile definition of sky fibre Copied to ThAr lt NNNN gt _COP2 tbl by command INIT FEROS ThAr lt NNNN gt Format MIDAS Table e Filename wlc coeffs1 tbl Keyword COEF WLC Content Table with wavelength calibration coefficients of object fibre from global fit Copied to ThAr lt NNNN gt _WLC1 tbl by command INIT FEROS ThAr lt NNNN gt Format MIDAS Table e Filename wlc coeffs2 tbl Keyword COEF WLC Content Table with wavelength calibration coefficients of sky fibre from global fit Copied to ThAr lt NNNN gt _WLC2 tbl by command INIT FEROS ThAr lt NNNN gt Format MIDAS Table e Filename ThAr50000 tbl Keyword COEF WLC Content Table with wavelengths of calibration lines optimized for resolving power R 50000 Used for wavelength calibration Available in MIDAS directory midas 97NOV contrib feros data calib Format MIDAS Table e Filename BLAZE tbl Keyword COEF WLC Content Table with blaze wavelengths of orders Used for order merging Available in MIDAS directory midas 97NOV contrib feros data calib calib0002 mt Format MIDAS Table 50 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 autoreduce e Filename ferro lt NNNN gt mt Content rawimage in FITS format as transferred to the instrument workstation Format pixel pixel e Filename raw image bdf Content MIDAS frame after prere
34. UE 22664 000 M2 setting mm GEOELEV 2335 Elevation above sea level m GEOLAT 29 2543 Tel geo latitute North deg GEOLON 70 7346 Tel geo longitute East deg ID y 3 38 TCS version number MOON DEC 3 07020 03 04 12 7 DEC J2000 deg MOON RA 11 757354 00 47 01 7 RA J2000 deg OPER F Labrana Telescope Operator TRAK RATEA 15 000000 Tracking rate in RA arcsec sec TRAK RATED 0 000000 Tracking rate in DEC arcsec sec FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 59 HIERARCH ESO TEL TRAK STATUS NORMAL Tracking status HIERARCH ESO TPL DID ESO VLT DIC TPL Data dictionary for TPL HIERARCH ESO TPL EXPNO 1 Exposure number within template HIERARCH ESO TPL ID FEROS_ech_obs_objsky Template signature ID HIERARCH ESO TPL NAME FEROS obs object sky Template name HIERARCH ESO TPL NEXP 2 Number of exposures within templat HIERARCH ESO TPL PRESEQ FEROS_ech_obs_objsky seq Sequencer script HIERARCH ESO TPL START 2004 07 08T21 23 01 TPL start time HIERARCH ESO TPL VERSION 71 0 i Version of the template ORIGFILE FEROS_ech_obs_objsky_0001 fits Original File Name ARCFILE FEROS 2004 07 08T21 23 29 396 fits Archive File Name CHECKSUM 9aoDJUoA9ZoAGZoA ASCII 1 s complement checksum The corresponding FEROS MIDAS descriptors When converting FITS files to MIDAS bdf some of the standard FITS keywords
35. Visitor mode runs including raw data DRS Pipeline products FFHV images and relevant log files are provided via CD and or DVD according to taste These CDs are created by La Silla SciOps staff For Visitor Mode programmes the CDs and or DVDs are usually ready for the observer to take home with him her before departing from the observatory normally in the afternoon after the end of the last night of observations The Visitor must complete the web based backup request form which is accessible from the SciOps home page Since Period 76 Data Packages For Service Mode programmes are prepared by ESO s Data Manage ment Department Data packages are sent via mail to the programme PIs upon completion of the entire set of OBs or the end of the relevant ESO period whichever comes first Typically one night of FEROS observations plus calibrations will fill one CD raw data being gzipped and often entire runs will fit on a single DVD 53 Appendix E The FEROS FITS header SIMPLE BITPIX NAXIS NAXIS1 NAXIS2 PCOUNT GCOUNT BZERO BSCALE ORIGIN DATE TELESCOP INSTRUME OBJECT RA DEC EQUINOX RADECSYS EXPTIME MJD OBS DATE OBS UTC LST PI COI OBSERVER CTYPE1 CTYPE2 CRVAL1 CRVAL2 CRPIX1 CRPIX2 CDELT1 CDELT2 EXTEND HIERARCH ESO ADA GUID STATUS 32768 0 1 0 ES0 LSO 2004 07 08T21 25 30 MPI 2 2 FEROS SolarSpectrum 194 999415 29 99999 2000
36. and filter have to be entered For extended sources magnitudes are given per square arcsec In addition to the target the sky conditions phase of the moon and FWHM of seeing disc must be chosen The final entry is the exposure time The output for the spectral format consists of a table listing the spectral format i e the wavelength at the order maximum the order separation in the direction perpendicular to the dispersion the start and end wavelength of each order and the start and end of the Free Spectral Range i e the non overlapping part of the consecutive orders An second table with expected counts and graphs of Efficiency Object and Sky counts Imax and S N can optionally be displayed For clear skies and excellent seeing i e DIMM seeing better than larcsec the ETC is accurate to within 10 30 For Service Mode programmes if a constraint of PHOT or CLEAR conditions is specified it is advisable to multiply the exposure times determined by the ETC by TWO in order to maximise the probablity of achieveing the required S N in typical conditions If you are aiming your FEROS Service Mode programme as a filler programme and are therefore willing to accept THIN to THICK conditions then you should multiply the exposure times determined by the ETC by FOUR in order to maximise the probablity of achieveing the required S N in such conditions however bearing in mind that your OBs always have the chance of being executed in better
37. and inspect the spectra to produce intensity traces and to compute the statistics of pixels values in a subwindow Previous exposures can be reloaded 6 2 Pipeline reduction of FEROS data FEROS was delivered to ESO with a reduction pipeline which supports all readout modes and binnings The science data are calibrated with calibration exposures obtained in the afternoon before the start of the night The FEROS Calibration Plan cf section 4 1 ensures that ESO maintains and provides on a daily basis bias images internal spectroscopic flatfield spectra calibration lamp spectra solar spectra and spectrophotometric standard star spectra The CCD characteristics like read out noise and gain are currently measured on a daily basis Dark current are carried out once every ten days and are available on request from the ESO archive for SM programmes if not by chance included in the data package and in the data package for Visitor Mode programmes Both optimum and standard extraction modes are possible however there are currently problems of an unknown origin with the optimum extraction method resulting in a semi sinusoidal modulation of some spectra which appears and disappears from exposure to exposure This problem seems to be relevant to high S N spectra only and has not been seen in low S N spectra More information about the FEROS pipeline and Service Mode data packages is given in appendix A and available under http www ls e
38. are converted into standard MIDAS descriptors The following table lists the most important conversions FITS MIDAS OBJECT IDENT RA 0 POS 1 DE 0 POS 2 DATE OBSO_TIME 1 TM STARTO_TIME 5 EXPTIME O_TIME 7 Appendix F Acknowledgements This User Manual is based on the UVES User Manual issue 1 9 dated June 2004 kindly provided by C Ledoux and S Hubrig of Paranal instrument support the current maintainers of the UVES manual The original authors of the UVES User Manual are A Kaufer S D Odorico and L Kaper and their contribution to this manual via their original authorship of the UVES manual is hereby acknowledged This user manual also draws extensively from the revised FEROS User Manual written by John Pritchard and his extensive contribution to this manual is likewise gratefully acknowledged 000 60
39. atalogue Filename Dark cat Content Catalogue with DARK exposures Format MIDAS catalogue Filename Objects cat Content Catalogue with SCIENCE exposures Format MIDAS catalogue Filename FF lt NNNN gt bdf Keyword RAW_IMG Content average flatfield frame from catalogue HE cat filenum is taken from the first file in the catalogue Format position nm position mm Filename FF lt NNNN gt extl bdf Keyword RAW IMG FLAT IMG Content Extracted flatfield orders of object fibre Format position mm order 47 48 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 FilenameFF NNNN gt ext2 bdf Keyword RAW IMG FLAT IMG Content Extracted flatfield orders of sky fibre Format position mm order Filename ThAr lt NNNN gt bdf Keyword WLC_IMG Content average calibration frame from catalogue ThAr cat filenum is taken from the first file in the catalogue Format position nm position mm Filename ThAr lt NNNN gt ext1 bdf Keyword WLC IMG Content Extracted calibration orders of object fibre Format position mm order Filename ThAr lt NNNN gt ext2 bdf Keyword WLC_IMG Content Extracted calibration orders of sky fibre Format position mm order Filename ThAr lt NNNN gt lines1 bdf Keyword LINE POS TBL Content Table with found calibration lines of object fibre order by order dispersion co efficients are stored in the descriptor DCOEF D 1 195 with 5 polynomial coefficients per order used for
40. conditions than your constraints it is thus best to break the total exposure into 2 4 individual exposures so as to avoid the possibility of saturation 3 5 Target Acquisition and Guiding The pointing of the MPG ESO 2 20 m telescope is accurate to 5 arcsec rms this does however not guarantee that the target will be centered on the fibre after telescope pointing In case of crowded fields the identification of the object is carried out by the astronomer or in case of service observa tions with help of a finding chart provided by the user Final coordinates and when required the finding chart in the format specified in the Proposal Instructions must be submitted during Phase II of the proposal preparation The target coordinates must be accurate to lt 1 to avoid an unnec essary waste of telescope time during the target acquisition phase In most cases the Digital Sky Sur vey DSS can be used to prepare finding charts and is accessible from the ESO world wide webpages FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 25 http archive eso org dss dss or using Skycat For crowded fields or faint extended objects other well suited image sources have to be used The DSS and other tools can be accessed through the Proposal Preparation and Submission page http www eso org observing proposals which allow the calculation of site sky ephemerides the determination of object observability airmasses etc For the observation of m
41. d Extended Range chelle Spectrograph FEROS is a bench mounted thermally controlled prism crossdispersed chelle spectrograph now installed at the MPG ESO 2 20 m tele scope at ESO La Silla It is designed to be a high resolution high efficiency versatile spectrograph providing in a single spectrogram almost complete spectral coverage from 350 920 nm Precise radial velocity work accuracies of 25m s or better is also possible especially via the Object Calibration mode The spectrograph is fed by two fibres providing simultaneous spectra of object plus either sky or one of the two calibration lamps wavelength calibration and flat field The fibres are illuminated via 2 0 arcsec apertures on the sky separated by 2 9 arcmins A small amount of rotation of the telescope adapter is possible in the rare case that a field star by chance falls on the sky fibre The resolving power is 48 000 achieved with a two slice image slicer over the spectral range of 350 920 nm spread over 39 e helle orders The detector is an EEV 2kx4k CCD The instrument is built for maximum mechanical stability and for accurate calibration of the wave length scale down to an accuracy of at least 50 m s Wavelength calibration spectra can be obtained simultaneous with the science exposure for observations requiring higher accuracy FEROS was first installed at the ESO 1 52m telescope in late 1998 In October of 2002 FEROS was transferred from the ESO 1 52 m telesc
42. duction of the rawimage Format position mm position mm e Filename back bdf Content Background subtraced frame Format position mm position mm e Filename back str C1 bdf Content Straightened frame of object fibre Format position mm pixel e Filename back str C2 bdf Content Straightened frame of sky fibre Format position mm pixel e Filename bf lt NNNN gt ext1 bdf Content Extracted orders of object fibre Format position mm order e Filename bf lt NNNN gt ext2 bdf Content Extracted orders of sky fibre Format position mm order e Filename f lt NNNN gt ext1 bdf Content Extracted and flatfielded orders of object fibre Format position mm order e Filename f lt NNNN gt ext2 bdf Content Extracted and flatfielded orders of sky fibre Format position mm order e Filename rebinnedl bdf Content Wavelength rebinnded orders of object fibre Format wavelength order e Filename rebinned2 bdf Content Wavelength rebinnded orders of sky fibre Format wavelength order FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 e Filename f lt NNNN gt 1 bdf Content Merged and wavelength calibrated spectrum of object fibre Format wavelength A e Filename f lt NNNN gt 2 bdf Content Merged and wavelength calibrated spectrum of sky fibre Format wavelength 51 Appendix C Naming convention for DRS products DRS products are given the following naming convention
43. e exposure This will take into account any significant change in the air pressure humidity and or in the air temperature see Chapter 4 2 The same applies to the FF at wavelengths where the effect of fringing is important A gt 650 nm As an example we consider a target where the ETC computes an exposure time of 180 minutes to reach the desired S N ratio and it is required to obtain the highest accuracy in the wavelength calibration and in the FF correction We split the exposure time into three integrations of 1 hour to permit median filtering of the cosmic rays Additionally both FF and wavelength calibrations exposures are attached for high radial velocity accuracy and accurate flatfielding We thus have telescope pointing 360 sec FCU Adapter setup 60sec 1 exposure 3600 sec read out time 41 sec FCU Adapter setup 60 sec ThArNe exposure 10sec read out time 41sec FCU Adapter setup 10sec LampWarmup 60sec FF exposure 60sec read out time 41sec x three times This leads to a total time of 12189 sec or 203 15 m of which 183 5 m is integration and just under 20 m is overhead 741096 The overhead becomes relatively more important if many short exposures with many attached calibrations are required FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 27 3 7 Check list 1 Decide whether to OBJSKY or OBJCAL mode 2 Decide for visitor justification needed or service mode 3 Use ETC to check exposure time 4 An
44. e for Service Mode programmes For SM programmes requiring high precision radial velocities either the OBJCAL mode should be used or WLC exposures should be attached to each science observation To this purpose the user can insert As it was when FEROS was at the ESO 1 52m telescope FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 31 in the OB after the Observation Templates a so called attached calibration template where a lamp is selected and all instrument parameters except the exposure time are left unchanged The telescope will lose the guide star during the lamp operation because the SCSM will obscure the beam from the telescope to the fibrehead however in typical WLC exposure times errors in tracking will be small and reacquisition of the target onto the fibre to take another science exposure will be fast The instrument currently repositions the moving functions with great accuracy Changes in temperature pressure and or humidity change the refractive index of air and hence change the path of the beam through the spectrograph and hence finally the position of the spectra on the CCD For the normal range of temperature humidity and atmospheric pressure of the obser vatory temperature has the biggest effect on the refractive index of air Furthermore temperature changes also affect the instrument itself causing it to shrink or expand therefore the temperature of the spectrograph is controlled by placing it inside the FEROS Cli
45. e from 1 0 316 times the exposure time of the calibrations Since useful ThAr can be obtained with exposure times from 10 100sec this means OBJCAL exposures from 10 31 600 sec are possible though of course other constrainst limit maximum reasonable exposure times of the order of 1 hr 2 6 FEROS WFI Adapter The FEROS WFI Adapter includes the M3 mirror fibrehead Sliding Calibration Selection Mirror SCSM the FEROS FibreHead Viewer FFHV including a standard ESO large format Technical CCD and an Atmospheric Dispersion Corrector ADC With M3 in the telescope beam is reflected onto the downward facing fibrehead which is a polished solid aluminium block The SCIENCE fibres are mounted into the back of the fibrehead and are illuminated via the fibrehead apertures holes 2 0 arcsec in diameter on the sky separated by 2 9 arcmins oriented EW of each other in the FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 17 default orientation of the telescope rotator The FWA also includes the Sliding Calibration Selector Mirror SCSM which is used to control which of the SCIENCE fibres is illuminated by light from the CALIBRATION fibres whose exit is also mounted in the Adapter and the Atmospheric Dispersion Corrector 2 7 Spectral Coverage Resolution and Overall Efficiency
46. e light beam from the telescope is split in two arms UV to Blue and Visual to Red within the instrument The two arms can be operated separately or in parallel via a dichroic beam splitter The resolving power is about 40 000 when a 1 arcsec slit is used The maximum two pixel resolution is 80 000 or 110 000 in the Blue and the Red Arm respectively Three image slicers are also available to obtain high resolving power without excessive slit loss The instrument is built for maximum mechanical stability and allows for accurate wavelength calibration An iodine cell can be inserted in the light beam for observations requiring extremely high accuracy for radial velocity measurements FORSI at UT2 since June 2004 can be used for spectroscopy in the spectral range 360 1100 nm Its overall efficiency is on average 2 times higher than UVES one reflection less in the telescope and simpler instrument optics but the maximum resolving power to be obtained with a 0 5 arcsec slit is 2 500 only FORS2 at UT1 is a replica of FORS1 but it will eventually include two transmission echelle gratings which when used in conjunction with a grism cross disperser will provide a resolving power of up to 6 000 and a wider spectral coverage comparable to that of UVES FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 5 e GIRAFFE which is part of the FLAMES instrument at the opposite Nasmyth platform of UT2 is the instrument which approaches UVES in resolution
47. e observing session might be 1 EXT_MODE controls the method used for the extraction of the spectra The three options are FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 43 SET FEROS EXT MODEC S the standard extraction is performed where the flux across the slit is ust summed SET FEROS EXT MODE M the standard extraction is performed as above but with clipping of cosmics SET FEROS EXT MODE O the optimum extraction is performed with clipping of cos mics In addition EXT MODE B for both is understood by autoreduce to execute standard and optimum extractions 2 MERGE MTD controls the merging of the orders The options are SET FEROS MERGE MTD SINC the default merging into a 1D spectrum with weighted adding of overlapping regions The lengths of the orders are determined from table BLAZE tbl SET FEROS MERGE MTD AVE should not be used SET FEROS MERGE MTD NOAPP the orders are not merge but written into individ ual 1D spectra the order number is appended to the filename as 4 digit number 3 REBIN_MTD controls the rebinning of the spectra The options are SET FEROS REBIN SCL I the rebinning is done into a linear wavelength scale The stepsize has to be set in the keyword REBIN STEP SET FEROS REBIN SCL O the rebinning is done into a logartithmic wavelength scale The stepsize has to be set in the keyword REBIN STEP A 6 Utility programs A 6 1 List of files An extended list of files with the most important heade
48. e spectral flux distribution but not the absolute level Solution To get the absolute level right one would need for example to do simultaneous contemporaneous photometry for example with WEI of the spectrophotometric standard star and the SCIENCE tar get in photometric conditions in order to tie down the absolute flux at at least one wavelength or one could do wide slit low resolution spectroscopy with for example EMMI of EFOSC 2 8 4 Bi modal CCD RON CCD Tests from which the Conversion Factor ReadOut Noise Linearity of the CCD can be calculated are run almost daily in at least one readout mode All parameters behave well and according to expectation except the ReadOut Noise RON which shows a bimodal distribution of values see for example http www 1ls eso org lasilla sciops 2p2 CCDs 60 FIERA LAMP5 225kHz 1 low 1x1 During the middle part of 2004 the measured RON varied between the two upper and lower values more or less on a daily basis Since we take tests only daily we can not be certain if it was not varying even faster than this e g on a time scale of hours therefore it is somewhat problematic to be certain of the exact value of the RON for any given image during this period In the latter part of 2004 the RON settled down to the lower value through until about July 2005 although with a return to bimodal behaviour during late Jan and early Feb of 2005 and with a slight change in the mean value of the lower value a
49. e type and allowed ranges of the parameters some of the parameters have to be set by the observer FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 7 Wavelength calibration Spectrum obtained from a reference emission line lamp The wave lengths of the many emission lines are accurately known and are used to transform pixel space into wavelength space 1 8 Abbreviations and Acronyms AT BOB CAL CCD CD ESO ETC EM FCU FEROS FV FWA IS LSO OB OS OBS P2PP RTD SCSM STD SM TSF VLT VM Acquisition Template Broker for Observations Blocks Calibration exposure Charge Coupled Device Crossdisperser European Southern Observatory Exposure Time Calculator Exposure Meter FEROS Calibration Unit Fibre fed Extended Range chelle Spectrograph Fibrehead Viewer FEROS WFI Adapter Image Slicer La Silla Observatory Observation Block Observation Software Observation Template for a scientific target Phase II Proposal Preparation Real Time Display Sliding Calibration Selection Mirror Standard star Service Mode Template Signature File Very Large Telescope Visitor Mode Chapter 2 Instrument Characteristics 2 1 Opto mechanical layout Figure 1 1 gives the optical layout of FEROS The complete instrument consists of three main parts e The FEROS WFI Adapter e The Spectrograph e The FEROS Calibration Unit The FEROS WFI Adapter FWA is mounted at the Cassegrain focus of the MPG ESO 2 20 m telescope
50. e visiting astronomers who come to the La Silla Observatory to use FEROS The sixth Chapter summarizes the properties of the pipeline reduction carried out for data obtained using the standard set ups of the instrument 2 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 1 2 Information available outside this manual If you cannot find a specific piece of information in the FEROS User Manual or in case you have re maining questions please contact http www eso org observing support html or more specif ically e For information on the instrument performance and Phase I and Phase II proposal preparation please contact the User Support Group usd help eso org e For questions directly related to your granted observing run in Visitor Mode please contact La Silla Science Operations lasilla eso org e For Phase II preparation of Observation Blocks OBs follow the instructions given in the FEROS Template Reference Guide http www 1s eso org lasilla sciops 2p2 E2p2M FEROS e For checking on possible recent changes in the instrument not yet recorded in the current version of the User Manual consult the FEROS web page at http www 1s eso org lasilla sciops 2p2 E2p2M FEROS e Information on the current instrument performance can be found on the FEROS Quality Con trol pages at http www 1s eso org lasilla sciops 2p2 E2p2M FEROS InstrumentCharacteristics InstrumentEfficiency html 1 3 Capabilities of the Instrument ESO s Fibre fe
51. ename in the MIDAS calib data spec ctio directory 38 Appendix A Using the DRS pipeline at the telescope The FEROS on line data reduction software DRS gives the possibilty for a complete standard reduction of the science spectra which arrive during the night from the CCD system A 1 Installing at home The on line DRS is based on the MIDAS context feros which has been distributed with MIDAS since version 98NOV A short intoduction to the MIDAS context feros is found here The DRS as run at the telescope is available in the form of a gzipped tar archive FEROS DRS tgz and should be obtained from the La Silla FEROS DRS web page http www ls eso org lasilla sciops 2p2 E2p2M FEROS DRS To install the package follow the instructions in the README file http www 1s eso org lasilla sciops 2p2 E2p2M FEROS DRS FEROS DRS README also included in the FEROS DRS tgz file Various parameters and techniques can be applied to improve the quality of the reduction over that typically achieved at the telescope The version of the online DRS in the directory midas MIDASVERSION contrib feros locproc is now out of date and should only be used for data older than October 2002 On the 1 of November 2003 the content of the FEROS FITS image header records were complete revised and due to the change over from the Copenhagen University BIAS CCD controller system to the ESO standard FIERA CCD controller system The standard version of the
52. ervations Scientific observations of selected of targets and the associated calibrations have been obtained during the FEROS Commissionings in October and November 2003 and in March 2005 They are available as public data from the ESO archive Moreover all calibrations since October 2003 are public domain as are all SCIENCE data more than one year old and all are obtainable from the ESO Archive 1 6 Bibliography 1 FEROS I Template Manual 2p2 TRE ESO 22400 0001 version 1 0 09 07 2004 J Pritchard 2 P2PP User s Manual VLT MAN ESO 19200 1644 Version 2 7 12 01 04 F Comer n D Silva 1 7 Glossary Acquisition Accurate positioning of the telescope in order to center the target on the spectrograph fibre aperture Atmospheric Dispersion Correction ADC unit This unit can be inserted in the pre fibrehead area of FEROS to correct for atmospheric dispersion BIAS frame Read out of the CCD detector of zero integration time with shutter closed The registered number of electrons per pixel has to be subtracted from a science exposure because these were not created by photons from the source FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Calibration Procedures to remove the instrumental signature from the scientific data e g by subtracting BIAS frames and by dividing through the flatfield Camera FEROS has a dioptric camera imaging the dispersed parallel beam on one CCD detector Charge Coupled Device CCD Electron
53. eso org lasilla sciops 2p2 E2p2M FEROS InstrumentCharacteristics InstrumentEfficiency html The predicted global instrument efficiency is higher than 2096 from 400 to almost 800 nm With these efficiencies and an efficiency of 60 for the 2 20m telescope in good observing conditions a spectrum with a S N of 100 in V can be obtained in 10 minutes for a 10th magnitude star while approximately one hour is required to reach a S N of 10 for a star of 16 5 mag Furthermore making appropriate assumptions on the reflectivity of the three telescope mirrors also tabulated at the above webpage the overall telescope instrument detector efficiency has been computed and compared with measurements of standard stars Observations of spectrophotometric standard stars are acquired on most nights and are archived at http www ls eso org lasilla sciops 2p2 E2p2M FEROS InstrumentCharacteristics InstrumentEfficiency html Typically due to imperfect atmospheric transparency less than ideal seeing i e worse than 1 0 arc sec and imperfect focusing of the telescope peak efficiencies of 10 17 are achieved from night to night though 2096 peak efficiencies are certainly not unknown Observations agree well with the oretical expectations with a maximum peak efficiency actually slightly exceeding expectation being measured on occasion The design specification for the transmission of the the ADC is at least 9096 across the complete spectral range of FEROS
54. fic CCD is given in Tab 2 1 The detector consists of one EEV CCD EEV 44 82 Windowing of the CCD is not allowed Two fully supported read out modes of the CCD are available in both visitor and service mode 1 Low gain fast read out 225kHz 1 low 41 sec readout 2 High gain slow read out 60kHz 1 high 148 sec readout Both 1x1 and 2x2 binning are possible in both read out modes The default readout mode is 225kHz 1 low 1x1 A third experimental very fast read out medium gain readout mode 625kHz 1 med is available in visitor mode only and only at 1x1 binning The second digit in binning applies to the direction of the spectral dispersion The characteristics of these modes are given in Tab 2 1 The linearity of the CCDs is measured to be better than 1 over the range from 200 e to the saturation limit Note that counts per pixel above 50000 ADU should be avoided in the low gain readout mode because of non linearity The CCD parameters are periodically remeasured as part of the FEROS calibration plan http www 1s eso org lasilla sciops 2p2 E2p2M FEROS CalPlan index html 14 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Table 2 1 Measured properties of FEROS scientific CCD July 2004 values Where relevant the properties given are for the 1x1 readout mode only Properties for the 2x2 mode are still pending EEV 5096 at 350 nm 5896 at 370 nm 7296 at 400 nm 8596 at 450 nm Quantum efficiency 8596 at 500 nm 859
55. fter the upgrade of the CCD FIERA system in late June In about July the RON jumped up to the upper value where as of this writing it seems to be stable at least for the time being which at least is better than varying on a hourly daily but unknown timescale 2 8 5 Low flux level in bluest orders in Flatfields At the ESO 1 52m telscope just before moving FEROS to the 2 20m telescope the S N level in the bluest order was 15 in comparison to a peak S N of 1200 in the best illuminated orders in an 20 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 exposure time of 45sec Immediately after arriving at the 2 20m the S N level in the bluest order was 0 in comparison to a peak S N of 300 in the best illuminated orders in an exposure time of 7 600 sec clearly a problem After much effort it was discovered that neutral density filters used inside the Calibration unit were not very neutral and infact strongly attenuated the blue flux of the internal flatfield lamps These were thus replaced with a combination of filters whose aim was to attenuate the brightest wavelengths from the flatfield lamps i e mostly the red part while leaving unaffected as much as possible the fainter wavelengths of the flatfield lamps i e mostly the blue part This effort has resulted in raising the S N in the bluest order to approximately 50 in comparison to a peak S N of 800 in the best illuminated orders in an exposure time of 2 4sec Clearly the situation
56. he absolute flux at at least one wavelength or one could do wide slit low resolution spectroscopy with for example EMMI of EFOSC 4 7 Quality Control All calibrations acquired with the Daily Health Check OBs the StanCal OBs or the CALOB OBs are pipeline processed and used to initialise the DRS Parameters of the master images and the DRS initialisation e g BIAS level FF lamp flux levels RMS of wavelength solution are extracted and plotted to monitor for trends and as indicators of possible problems e g aging of lamps etc These plots are available online at http www 1s eso org lasilla sciops 2p2 E2p2M FEROS QC 4 8 Special calibrations 4 8 1 Use of reference stars to correct for fringing or atmospheric lines Stars with featureless spectra typically white dwarfs or fast rotating hot stars can be used to provide a good template to correct for fringing as an alternative to the use of internal flatfield lamps These spectra can also be used to identify and estimate the depth of atmospheric H20 and Oz absorption lines Stars of magnitudes between 5 and 9 are best suited for this type of observations because they require short exposures but do not saturate the detector at the shortest shutter opening times S These spectra can be helpful for order tracing in the bluest orders in older data where the Hal Hal lamp flux was insufficient FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 33 The OBs for these stars shou
57. he end of each integration the CCD frame is read out by the FIERA controller and transferred to the Instrument Workstation and subsequently to the archive At the same time the frames are displayed automatically on a Real Time Display RTD panel They can be analysed using the standard RTD tools Previous exposures can be re loaded when necessary Data obtained with observing templates are also reduced on line by the FEROS instrument pipeline using a pre populated calibration database The raw files and the products of the pipeline are FITS files cf section 6 2 They can be assessed and inspected by the astronomer on the assigned off line WS which is also available for running the major image analysis systems like MIDAS IDL and IRAF This preliminary reduction extraction wavelength calibration flat fielding provides advanced information on the quality of the obtained data but has to be regarded as a quick look reduction facility 3 As against maintenance templates Implemented within a standard MIDAS context Context feros of course Chapter 6 The reduction of FEROS data 6 1 Real Time Display and quick look As as they are read out by the FIERA Controller and transferred to the instrument WS the CCD frames are automatically displayed on a Real Time Display RTD panel on a screen of the instrument WS The visiting astronomer can use the standard tools of the RTD on the astronomer s offline WS to visually display
58. he guiding images themselves insures that the reference position of the fibre is always accurately known and accounts for adapter flexure which could cause the apparent position of the fibre to shift on the FFHV In practice however it is found that the FEROS WFI Adapter is very rigid and flexure from one extreme pointing of the telescope to another e g from the maximum western pointing to the maximum eastern pointing is negligable The FFHV image is automatically saved at the end of each acquisition It is included in the observers data package both Service and Visitor mode The FFHV images are NOT archived in the ESO archive due to non DICB compliance of the FFHV image headers 3 6 Computing time overheads for your program By using the FEROS Exposure Time Calculator the user obtains estimates of the observing time needed to reach the desired S N ratio depending on the object magnitude and observing configuration and conditons In order to arrive to the total observing time in hours or nights required for the program it is necessary to add the time for the various actions related to the scientific observation When applying for service mode observations the computation of the overheads is required and has to be included in the application The current date of this issue of the UM estimate of the overheads is provided below e Telescope pointing target acquisition and centering on fibre Assuming that the telescope is moving to a new ob
59. ic 2D array detector converting photons into electrons Cross disperser prism An echelle spectrograph contains two dispersive elements in the case of FEROS one grating and one prism The grating is the echelle grating the prism is called the cross disperser prism The cross disperser prism determines the distance between the echelle orders Fibrehead Viewer Simple optics which focus the light reflected by the fibrehead onto a technical CCD detector They are used to center the targets on the fibre and for guiding Flatfield Spectrum obtained from light source with a flat i e without spectral features energy distribution e g a tungsten lamp The registered signal provides information about the re sponse of the detector allowing a determination of the variation in sensitivity from pixel to pixel the echelle order shape the presence of bad columns on the detector etc Grating One of the main light dispersing elements of FEROS is the echelle grating Guide star A point source used for accurate tracking and active control of the telescope mirrors Image slicer This device converts a two dimensional image e g of a star in the focal plane of the telescope into a one dimensional slit In this way the light that normally would fall outside the slit especially when using a narrow slit for high spectral resolution is fed to the spectrograph Maintenance Technical procedures developed to control and maintain the quality of telescope
60. ide an overview of the two FEROS observing modes Light from the two fibres simultaneously recorded on the detector permits two observing modes e Object Sky OBJSKY e Object Calibration OBJCAL Apart from the instrument mode a decision has to be made regarding the acquisition of the target Under normal conditions the target is centered directly on one of the fibrehead apertures normally the one defined as the OBJECT fibre due to its superior throughput see figure 2 3 It is none the less possible to acquire the target onto the SKY CALIBRATION fibre aperture though it is hard to imagine any circumstance where this would be scientifically justifiable Observing in the two different modes is fully remotely controlled Both modes are offered in both Visitor and Service modes In both modes the internal flatfield Hal Hal and both wavelength calibration ThArNe and ThAr Ne light sources are available for the two fibres for calibration spectra via remote control of the FCU At the 1 52m it was necessary to manually change the fibre configuration at the telescope to switch between modes At the 2 20m switching is now achieved via positioning of mirrors via remote control FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 23 3 2 1 The Object Sky Configuration In the OBJSKY mode the two fibres record the star light and nearby sky background simultaneously The Sliding Calibration Selection Mirror in the FEROS WFI Adpater see sect
61. igure 2 3 The relative fibre efficiency in the sense of OBJECT SKY fibre The raw frame is a solar spectrum Each point represents one of the echelle orders http www ls eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr The Image Slicer TBD See the original FEROS Final Design Report downloadable from http www 1s eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr The First Colimator TBD See the original FEROS Final Design Report downloadable from http www 1s eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr The Echelle Grating TBD See the original FEROS Final Design Report downloadable from http www ls eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr The Flat Folding Mirror TBD See the original FEROS Final Design Report downloadable from http www ls eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr The Second Collimator ps gz ps gz ps gz ps gz ps gz FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 13 TBD See the original FEROS Final Design Report downloadable from http www ls eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr ps gz The Cross Dispersing Prism TBD See the original FEROS Final Design Report downloadable from http www ls eso org lasilla sciops 2p2 E2p2M FEROS Documentation fdr ps gz The Camera TBD See the original FEROS Final Design Report downloadable from http www ls eso org lasilla sciops 2p2 E2p2M FE
62. ime taking into account specific atmospheric conditions and determines the spectral format resulting from the selected instrument set up The Observing Blocks are prepared using another ESO provided software tool called P2PP see 2 and http www eso org observing p2pp Before preparing the observations it is advisable to review the FEROS webpages http www ls eso org lasilla sciops 2p2 E2p2M FEROS which give information on current problems and possible new instrument artifacts detected during the current observing period and not yet described in the FEROS User Manual A FEROS data reduction pipeline is also running at the Observatory It enables automatic extraction and wavelength calibration of all spectra of stellar objects taken with FEROS in 1x1 binning readout modes It permits an on line check of the quality of the observations resolution S N in the extracted spectra The science data are calibrated with calibration exposures obtained on a daily basis as part of the FEROS Calibration Plan Note that the FEROS on line pipeline is intended as a quick look and quality control tool and was designed for robustness of the reduction and not for best possible reductions The reduced data should be checked or compared with offline reprocessed data before beeing used for for publication 3 2 FEROS instrument modes and basic choices After the detailed description of the FEROS spectrograph its subsystems and functions Chapter 2 we prov
63. inting at the softlink in data backlog lt yyyy mm dd gt It is this fero lt NNNN gt mt file that is processed by the DRS using the command loadccd fero lt NNNN gt where filenum is the running 4 digit filenumber of the CCD frame The loadccd program itself loads the frame fero lt NNNN gt mt into the display e adds the incoming file to the catalogue Feros cat starts the automatic reduction via autoreduce fero lt NNNN gt runs DRS initialisation automatically as appropriate if StanCal or CALOB OBs are being executed According to the four possible exposure types SCIENCE FLATFIELD CALIBRATION and DARK given in the descriptor EXPTYPE the autoreduce program starts the following actions e DARK adds the incoming BIAS files to the catalogue Bias cat If the file was generated by FIERA and if the OB name had StanCal in characters 5 to 11 and it is the first exposure of the template then the command init ThAr lt MMMM gt reset is run automatically adds the incoming DARK files to the catalogue Dark cat FLATFIELD adds the incoming file to the catalogue FF cat If the file was generated by FIERA and if the OB name had StanCal in characters 5 to 11 and it is the last exposure of the template then the command average cat FF cat is run automatically CALIBRATION adds the incoming ThArNe files to the catalogue ThAr cat If the file was generated by FIERA and if the OB name had StanCal in characters 5 to 11 and it is
64. ion YYYY MM DD gt CCD 60 Detector chip identification 1 Chip index EEN CCD 44 Detector chip name 2048 of pixels along X 4096 of pixels along Y 15 0 Size of pixel in X 15 0 Size of pixel in Y 1 X location in array 0 000000 Gap between chips along x 1 Y location in array 0 000000 Gap between chips along y 1 of chips in detector array 03 10 03 Installation date 0 00000000 Apparent 00 00 00 0 DEC at start ESO VLT DIC CCDDCS ESO VLT DIC FCDDCS Diction 1311 Unique exposure ID number 41 559 image readout time Normal Exposure type 41 682 image transfer time 1 Image sequencial number Normal Type of frame q Detector system Id feros FEROS Name of detector system 1 Chip to which the output belongs 0 00 Conversion from ADUs to electrons 0 00 Conversion from electrons to ADU R Output ID as from manufacturer 2 Output index R Description of output 2048 valid pixels along X 4096 valid pixels along Y 50 Overscan region in X O Overscan region in Y 50 Prescan region in X O Prescan region in Y 0 00 Readout noise per output e 2048 X location of output 1 Y location of output 1 of outputs O reference output 0 00000000 Apparent 00 00 00 0 RA at start R 225Kps Low Gai Readout clock pattern used normal Readout method 1 Number of readouts buffered in sin Fast Readout speed Feros shutter Shutter u
65. ion 2 6 is in the PARK position The ADC can be used to correct the light from the target for the effect of Atmospheric Dispersion For calibration purposes the internal flatfield or the wavelength calibration source are normally recorded through both fibres but each fibre can if desired be illuminated individually 3 2 2 The Object Calibration Configuration In the OBJCAL mode the object fibre is used as in the OBJSKY mode described above Light from one of the sources of the FCU is delivered to the sky fibre via the appropriate positioning of the Sliding Calibration Selection Mirror in the FEROS WFI Adpater see section 2 6 Then the light of the calibration source normally ThAr Ne but ThArNe or Hal Hal is also possible can be recorded throughout the whole object exposure to monitor the stability of the spectrograph The position of the neutral density filter wheel is set automatically according to the exposure time and the user specified Equivalent lamp exposure time With the OC observing mode and the software techniques described below a long term radial velocity accuracy of 25m s is reached for sharp lined solar like stars The ADC is NOT available in OBJCAL mode due to a physical conflict between the ADC and SCSM mechanisms 3 3 Introducing Observation Blocks An Observation Block OB is a logical unit specifying the telescope instrument and detector parameters and actions needed to obtain a single observatio
66. ionary EXECTIME 684 Expected execution time GRP 70 linked blocks ID E 163677 bservation block ID NAME 200 SolarSpectrum norm OB name OBSERVER UNKNOWN Observer Name PI COI ID 51020 ESO internal PI COI ID PI COI NAME UNKNOWN PI COI name PROG ID 60 A 9120 B ESO program identification START 2004 07 08T21 23 01 OB start time TARG NAME SolarSpectrum OB target name TPLNO 2 Template number within OB DET1 IMGNAME FEROS_ech_obs_objsky Data File Name AG FIBSELEC OBJFIB Fiber currently used SKY or OBJ AIRM END x 1 035 Airmass at end AIRM START 1 037 Airmass at start AMBI FWHM END 1 00 Observatory Seeing queried from AS AMBI FWHM START 1 00 Observatory Seeing queried from AS AMBI PRES END 773 20 Observatory ambient air pressure q AMBI PRES START 773 20 Observatory ambient air pressure q AMBI RHUM 23 Observatory ambient relative humi AMBI TEMP 12 85 Observatory ambient temperature qu AMBI WINDDIR 278 Observatory ambient wind directio AMBI WINDSP 3 30 Observatory ambient wind speed que CHOP ST F True when chopping is active DATE 2000 10 15T15 21 35 745 TCS installation date DID ESO 2P2 DIC TCS 1 8 Data dictionary for TEL DOME STATUS FULLY OPEN Dome status FOCU ID CA Telescope focus station ID FOCU LEN 8 009 Focal length m FOCU SCALE 11 650 Focal scale arcsec mm FOCU VAL
67. is currently better than it has ever been before but it would still be better to have a constant maximal signal to noise in all orders 2 8 6 Few and faint lines in bluest orders in wavelength calibration spectra With the default setting of the LINE THRES of 1000 0 in the default guess sessions used at the telescope and available from the web few if any lines are found in the bluest few orders of the wavelength calibration spectra For the medium and long ThArNe exposures of the calibration plan useful lines are evident but LINE THRES must be reduced to 100 in order to detect a few of these For the ThAr Ne no useful lines are evident until the third order above 3700 Solution Carefully adjust LINE THRES parameter for the ThArNe calibrations 2 8 7 CCD Cosmetic Defects The FEROS CCD is of good cosmetic quality The major defects are the several complete or partial bad columns see table 2 2 Table 2 2 CCD bad columns In the standard application of the FEROS DRS pipeline the entire columns are replaced by the means of the nearest row neighboors of each pixel Column s RAW FITS prered Im Row start finish 270 321 1675 4096 273 324 1675 1779 385 436 1616 1695 386 437 1617 4096 381 389 438 440 1617 1640 393 394 444 445 1622 1740 697 748 0868 4096 894 945 1514 2100 908 909 959 960 1501 1690 934 985 1475 1680 951 1002 1459 4096 967 1018 1454 1500 1009 1015 1060 1066 1415 4096 1113 1115 1164 116
68. ishes to repeat the initialization personally the basic sequence to follow is e Reset the image catalogues FF cat ThAr cat Dark cat Object cat by the command init reset e Acquire at least 2 biases 2 flatfield and 2 wavelength calibration images create an OB in p2pp e Initialize the DRS for the night with the command init guess 0 85 where guess is the name of a previously saved guess session Typically this is the session saved in the night 42 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 before The session names are formed automatically from the filenumber of the first calibration exposure in the catalogue ThAr cat and the prefix ThAr e g ThAr0741 Now the following initialization steps are performed e Initialization of the session keywords and tables INIT FEROS e Averaging of the frames of the respective catalogues FF cat ThAr cat e Setting of the CCD gain keyword according to descriptor CCD GAIN and the values specified in init prg e Locating of the echelle orders in the averaged flatfield LOCATE FEROS the fitted positions are shown in the display window e Standard reduction of the flatfield BACK FEROS STRAIGHTEN FEROS EXTRACT FEROS The extraction is done twice the first time the cross order profiles are determined for an optimum extraction with cosmic removal for the science exposures the second time the flatfield orders are extracted The name of the reduced flatfield is found in the key
69. itialisation of the FEROS MIDAS DRS in both 1x1 and 2x2 binning modes is executed The Daily Health Check OB currently consists of e In 225kHz 1 low 1x1 readout mode 2 BIAS frames 2 Hal Hal Flatfield frames with a peak intensity of approximately 30 000 ADU exposure times are adjusted periodically as lamp intensities evolve and old lamps are replaced with new ones 1 ThAr Ne Wavelength Calibration frames of 15 sec duration e In 225kHz 1 low 2x2 readout mode 2 BIAS frames 2 Hal Hal Flatfield frames with a peak intensity of approximately 30 000 ADU exposure times are adjusted periodically as lamp intensities evolve and old lamps are replaced with new ones 1 ThAr Ne Wavelength Calibration frames of 3 75 sec duration The afternoon calibrations are carried out via the execution of the Daily Health Check OB typically loaded into Bob from the OT tool This OB takes approximately 20mins to complete 28 FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 29 Table 4 1 FEROS Science Data Calibration Plan Note that same calibrations are applicable for both OBJSKY and OBJCAL mode Calibration number frequency 1 days purpose Internal Flatfields 10 1 1 creation of master flats attached Flatfields n o r high precision flatfielding Dome Flatfields n o r Fringe correction in red orders Internal Wavelength 12 1 1 dispersion solution resolving power attached Wavelength n o r high precision wave
70. ject at 180 degrees from the current pointing allowing for accurate acquisition onto the fibre and time for the autoguiding to get the object accurately centered on the fibre and finally GRABing the FFHV image the whole sequence can be completed in 5min If a blind offset acquisition is required acquisition can require up to 7min If the new target requires just a small motion of the telescope and then re acquisition of the guiding star 3min Please note though for Service Mode programmes since it is never known in advance the order of OB execution it is not possible to know if it will be a small preset and therefore in p2pp the execution time for the acquisition template is always 5min 26 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 or 7min for blind offset acquisition e Adapter and calibration unit set up and CCD read out time Changing from OBJSKY to OBJCAL mode or vice versa or changing from SCIENCE to CAL IBRATION exposures take at most 1 minute Changing from one CALIBRATION type to another e g from FF to wavelength calibration takes 10 sec When turning on the calibration lamps a warmup time must considered A study made 2005 10 03 showed that approximately 4mins of warmup time was required for the flatfield lamps to reach a stable flux level see http www ls eso org lasilla sciops 2p2 E2p2M FEROS TechnicalReports FFLampWarmUpTime index html For the calibration plan daytime calibrations the FF lamps are warmed
71. ld be prepared in Phase II by the observers who require them for their program A bright subsample of the hot flux standards stars is well suited for these observations Chapter 5 Observing This Chapter summarizes the instrument related information for the visiting astronomers coming to La Silla to observe with FEROS 5 1 Before the observing nights preparation of OBs Visiting astronomers are normally asked to come to La Silla one night in advance of their observing run They should arrive already well documented on the instrument properties and on the prepa ration of the OBs for their observing run or ready to finalize them if they have been prepared in advance at the home institute These activities take place on a Linux PC Workstation in the User s Computer Room in the Library building just below the hotel which can also be used for electronic mail correspondence with the outside world telnet ssh connection to the home institute access to the World Wide Web text file editing etc Normally a p2pp introduction i e advice on the OB preparation will be given by the support astronomer of the Observatory 5 2 During the night Observations with the FEROS instrument are carried out at the User Station of MPG ESO 2 20 m telescope console located in the RITZ Control Building located between the NTT and ESO 3 60 m telescopes From there all three La Silla telescopes offered to the ESO community and instruments are remotely con
72. length calibration Bias 5 IU creation of master biases Dark 1 1 10 creation of master darks Flux Standard n or response correction flux calibration Telluric Standard n Or removal of telluric spectrum Radial Velocity Std n o r absolute radial velocity calibration o r on request only corresponding OBs to be provided by user n number to be defined by user Each morning a standard set of calibration data are acquired A standard calibration data set is currently defined as e 5 BIAS frames e 10 Hal Hal Flatfield frames with a peak intensity of approximately 30 000 ADU exposure times are adjusted periodically as lamp intensities evolve and old lamps are replaced with new ones 2 ThAr Ne Wavelength Calibration frames of 3 sec duration e 2 ThAr Ne Wavelength Calibration frames of 15sec duration 2 ThAr Ne Wavelength Calibration frames of 30 sec duration e 2 ThArNe Wavelength Calibration frames of 3sec duration e 2 ThArNe Wavelength Calibration frames of 15sec duration e 2 ThArNe Wavelength Calibration frames of 30sec duration The morning calibrations are carried out automatically using the ESO CALOB tool The CALOB tool insures that morning calibrations are acquired for each readout mode actually used during the night Additionally to the standard sets of calibrations the following calibration data are acquired e 1 one hour DARK once every ten days e 2 Imin Solar spectra ADC OUT approx 1hr befo
73. ly the ThArNe source was available Since December 2004 both sources have been available and the Calibration Plan has included both lamps Neither lamp provides an ideal calibration source The ThArNe source provides better flux in the bluest orders but has numerous strongly saturated lines in the red orders This is a particular problem for the OBJCAL mode due to contamination of the object spectrum The ThAr Ne source on the otherhand mostly avoids contamination of the object spectrum but has poor flux in the bluest orders In an attempt to cover all possibilities the calibration plan therefore acquires arc line spectra with both lamps and at a range of exposure times Selection between the sources is made simply by the Rotating Selection Mirror RSM see figure 2 4 The RSM reflects the selected source or in the case of the ThArNe source keeps out of the light path into the collimator The FCU Shutter then selects which fibre s the beam illuminates After the shutter two lenses focus parts of the beam onto each CALIBRATION fibre input Between the lenses and the fibre inputs is a Neutral Density Filter Wheel NDFW which allows control of the flux level in OBJCAL mode so that it is possible to match the flux level in the calibration spectrum in long SCIENCE exposures to the flux obtained in the much shorter calibration exposures The dynamic range of the NDFW is approximately 0 0 2 5 thereby allowing flux matching OBJCAL exposures of exposure tim
74. mate Controlled Room where an airconditioning unit controls the air temperature T he design specification for this system is to be stable within 0 5 degrees Celcius In practice during a given night temperature stability is generally better than 40 2 degrees Celcius though from day to day the variations can be somewhat larger A continuously updated database of recorded environmental sensor data can be found at http www 1s eso org lasilla sciops 2p2 E2p2M FEROS EnvMonArchive In a night the air pressure at La Silla can change by several hPa while the humidty can and often does change by more than 50 However the FEROS Climate Controlled Room is a room built of insulated steel panels and is located inside another room in the center of the 2 20m telescope building i e it is to a certain extent isolated from the outside world and thus external environmental changes reach the instrument only slowly Image file headers contain values of the humidity inside the instrument encloure and temperatures at two locations within the instrument three within the FEROS Climate Controlled Room and one outside the FEROS Climate Controlled Room at the beginning and end of each exposure Ambient environmental data including air temperature humidty and pressure are also recorded in the headers 4 4 Flat fielding There is one internal flat fielding lamp Hal Hal provided by the FCU plus the possibility to make dome flatfields The internal lamp provides
75. n It is the smallest schedulable entity which means that the execution of an OB is normally not interrupted once it has been started In Service Mode OBs are executed once and once only when identical observation sequences are required e g repeated observations using the same instrument setting but different targets a series of OBs must be constructed In Visitor Mode it is possible to repeatedly execute the same OB The detailed definition of FEROS Observation Blocks and Templates is given in Ref 1 For example one would like to obtain a spectrum of a point source First the instrument mode has to be chosen OBJSKY or OBJCAL The instrument mode is set within the FEROS acquisition observation and calibration templates In addition the information on the target position has to be provided in the acquisition template For the observation itself either the FEROS ech obs objsky or the FEROS ech obs objcal template must be used according to which mode is required The parame ters to be set for both modes are the read out mode of the detector see section 2 4 and the exposure time and the binning For the OBJCAL mode the additional parameters of which lamp to use and the lamp warmup time must be specified If one likes to carry out a dedicated wavelength calibra tion after the science exposure the attached wavelength calibration template FEROS ech cal wave has to be added Together the three selected templates form an Observation
76. n order to achieve VLT standard DICB compliance Chapter 7 Other useful information 7 1 List of standard stars Any flux standard star can be used for flux calibration and blaze correction The standards to be preferred should have measurements at a step of 2 nm or less to have at least a few points for each echelle order For the pipeline reduction it is necessary to use stars for which the flux Table is available in MIDAS In particular flux standards from the MIDAS calib data spec ctio directory will be automatically recognised the efficiency will be calculated and reported The FEROS webpage http www 1s eso org lasilla sciops 2p2 E2p2M FEROS CalPlan contains a pointer to the lists of flux standards 7 2 Lists of arc lines Tables of the ThAr and Ne lines used in the pipeline reduction are available in the FITS table ThAr50000 mt contained in all guess session archives a selection of which are available from La Silla FEROS DRS web page http www ls eso org lasilla sciops 2p2 E2p2M FEROS DRS 7 3 Pointers to FEROS sample observations The FEROS webpage http www 1s eso org lasilla sciops 2p2 E2p2M FEROS ImageDB index html contains links to sample calibrations as well as information for obtaining scientific observations and calibrations available from the ESO Science Archive Database Provided the name of the standard is entered in the target name field of the acquisition template exactly as it is correspnding fil
77. n the converging f 8 beam coming from the telescope the first element is the FWA M3 which allows switching between FEROS and WFI in approximately 8 seconds When IN the M3 obscures the central approximately 4096 of the WFI field of view Then follows the ADC which is moved IN and OUT of the beam via an arm It consists of two sets of two counter rotating prisms each of 12mm diameter and 6mm thickness separated by 1 mm of air One prism set is mounted in front of each of the two Fibrehead apertures Each prism consists of a wedge of UBK7 glass cemented to a wedge of LLF6 glass with a ANTIREFLET anti reflection coating on the four prisms surface From midday solar spectra the measured total transmission of the TWO prims is above 90 for wavelengths above 3900A thus achieving the design requirement of 9096 or better transmission over the range 4000 9250 see figure 2 2 The overall modulation of the transmission curve is due to the antireflection coating 2 2 2 The spectrograph The light path The two f 8 beams OBJECT and SKY CALIBRATION either from the telescope and or the calibration unit arrive at the fibrehead where they enter the fibre apertures The beams are focussed onto the SCIENCE fibres by rod type microlenses After exiting the SCIENCE fibres it traverses the F N Adaption Lens System the Image Slicer the First Colimator then the Echelle Grating back to the first Collimator then the Flat Folding Mirror then the Second Collimator
78. n tool to obtain online radial velocities with respect to one reference exposure of the object It should be emphasized that the routines described here are meant as on line tools to obtain an estimate for the measured radial velocity shifts However to obtain high precision radial velocities over long periods dedicated reduction software and special operational precautions have to be taken This is beyond the scope of the FEROS on line DRS The algorithm works as follows The program crosscorrelates the calibration spectrum thar from the initialization of the night order by order with the corresponding calibration spectrum from the reference night tharref to obtain the zero point of the night FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 45 For the object spectrum obtained during the night object the program crosscorrelates the simulta neous calibration spectrum on the calibration fibre with the calibration spectrum on the calibration fibre from the initialization to obtain the drift correction between the zero point of the night and the actual object exposure The object spectrum object is crosscorrelated with the object spectrum from the reference night objectref The measured radial velocity shift is corrected for the zero point the drift during the night and the barycentric correction The final radial velocity is obtained by gaussian fitting of the histogram of the derived radial velocities of all orders To use the
79. nique identifier 0 001 Time taken to close shutter 0 001 Time taken to open shutter IRIS type of shutter 56 HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH HIERARCH ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO ESO FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DET DPR DPR DPR SOFW TELE TELE TLM1 TLM1 TLM1 TLM1 TLM2 TLM2 TLM2 TLM2 WIN1 WIN1 WIN1 WIN1 WIN1 WIN1 WIN1 WIN1 WIN1 MODE INT NO END ID NAME START END ID NAME START BINX BINY DIT1 DKTM NDIT NX NY ST STRX WIN1 STRY WIN1 UIT1 WINDOWS CATG TECH TYPE ADC1 ADC1 ADC1 ADC1 ADC1 ADC2 ADC2 ADC2 ADC2 ADC2 SWSIM ADCA NAME CALMIRR1 CALMIRR1 CALMIRR1 CALMIRR1 CALMIRR2 CAL
80. ope Light from the FCU is delivered to the fibrehead via the CALIBRATION fibres Table 4 2 lists the lamps and exposure times to be used for the default readout mode and how to derive suitable exposure times for the other readout modes 4 3 Calibration in wavelength The ThArNe and ThAr Ne lamps provides accurate wavelength calibrations over the complete spectral range when the FEROS matched line table available from in the MIDAS calib data and from the FEROS DRS web page http www ls eso org lasilla sciops 2p2 E2p2M FEROS DRS is used However neither lamp and no single exposure time provides an ideal calibration for all orders Therefore standard sets of calibrations include exposures with both lamps and with three different exposure times The rms of the wavelength fit achieved during the daily DRS initialisation using the combined i e all three exposure times ThArNe exposures is typically better than 0 006 A Wavelength calibration WLC exposures using either ThArNe or ThAr Ne lamps can be made simultaneously with the science exposures in the OBJCAL mode to account for the effects of changing temperature and or pressure or of a small earthquake Alternatively WLC exposures can be taken immediately before and or after the science exposures Typically however even for high precision radial velocity work it is only necessary to take a few WLC exposures dispersed through the night This is valid for Visitor Mode programmes but is NOT don
81. ope to the MPG ESO 2 2 m telescope In October November of 2003 it was upgraded to full VLT compliance i e OB controlled observing The main capabilities of FEROS are summarized in Table 1 1 The two spectral ranges 853 4 854 1 nm and 886 2 887 5 nm are lost due to non overlap of the spectral orders FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Table 1 1 FEROS characteristics and observing capabilities Wavelength range in one exposure object 4 sky 356 920 nm 39 orders 2 fibres Resolving Power with 2 slice image slicer R 48000 Entrance Aperture 2 0 arcsec Fibre Input Output Focal Ratio F 4 6 Spectrograph Beam Size 136 mm diameter Off axis Collimators F 11 cut from one parent paraboloid Echelle R2 79 lines mm 154 mm by 306 mm Crossdisperser Prism LF5 glass 55 apex angle Dioptric Camera Wavelength Range 350 900 nm F F 3 0 Focal Length 410 nm Field Diameter 69 mm Image Quality E80 lt 25 um Efficiency gt 85 96 CCD 2048 x 4096 15 um thinned Detection Efficiency without telescope 7 3 700 A 27 5 000 A 8 9 000 A Radial Velocity Accuracy lt 30 m s 1 4 FEROS within ESO A detailed overview of the different ESO instruments is given on the ESO homepage under Instru mentation http www eso org instruments In the choice of the best instrument for a given observing p
82. oving targets the acquisition templates allow to enter additional velocities in right ascension and declination in units of arseconds per second The target is identified on the image of the FEROS Fibrehead Viewer FFHV by the visiting astronomer or in case of service observations by the ESO staff astronomer The target is identified by clicking on it with the mouse and automatically positioned on the fibre The tracking of the telescope is corrected for errors of low frequency 1 Hz by an autoguiding facility Normally guiding is performed on the target itself on the fibre guiding on fibre using the FFHV But in crowded fields one or more field stars of comparable brightness i e within 3 mag within 10arcsec of the target a field star in the field of view of the FFHV can be used guiding on fieldstar In this case it is not possible to check the centering of the object on the fibre during the observation except by momentarily turning off the autoguiding however the guiding is reliable for at least 1hr so this is not normally necessary In extreme cases when there happens to be one contaminating field star near the target thus preventing guiding on fibre but no other field stars suitable for guiding within the field of view of the FFHV the WFI tracker chip can be used for guiding With a field of view of 10 x 21 arcmin a suitable guide star is ALWAYS available For guiding on fibre a Dynamic Centering algorithm which analyses t
83. r informations can be obtained with the command 00 listferos tablename filenum start filenum end where tablename is the name for the output table filenum start filenum end are the 4 digit filenum bers of the interval of files to be listed The program will ask at the end to prepare a printout on the laser printer It will take care of the proper formatting of the printer output It is recommended to use this program at the end of the night to check the integrity and completeness of the data files obtained during the night before archiving them on the COPY DAT A 6 2 Plot of temperatures A plot and a table with the spectrograph and room temperatures corresponding to the obtained CCD frames can be obtained with the command 00 temperature tablename filenum start filenum end where tablename is the name for the output table filenum start filenum end are the 4 digit filenum bers of the interval of files to be used In the table also the measured relative humidity is stored and can plotted with the command plo table tablename JD24 RHUM 44 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 A 6 3 Signal to Noise Ratio After a spectrum fero lt NNNN gt mt of a science object has been passed the on line DRS the achieved Signal to Noise Ratio SNR can be tentatively measured in a line free region of the spectrum with the following command snr lt NNNN gt start end fibrenum where the parameters start end de
84. re sunset weather permitting e 2 Imin Solar spectra ADC IN approx 1hr before sunset weather permitting e 2 2min Spectrophotometrcic Standard star spectra ADC OUT weather permitting at least one star per night 30 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Table 4 2 Exposure times for Calibration Lamps unbinned high gain fast readout mode 225kHz 1 low 1x1 CCD pixel saturation occurs at 65000 ADU but the response is linear only to 50000 ADU Exposure times have to be scaled down by a factor of 1 4 for the 2x2 binning and by the ratio of the Conversion factors for the high gain slow 60kHz 1 high 1x1 and medium gain Very Fast 625kHz 1 med 1x1 readout modes LAMP MAXIMUM EXPOSURE INTENSITY TIME REMARKS ADU sec Hal Hal 30000 2 4 ThArNe 3 15 30 ThAr Ne 3 15 30 e 2 2min Spectrophotometrcic Standard star spectra ADC IN weather permitting at least one star per night The Calibration Plan is executed by the observatory staff Visiting astronomers who require addition calibrations beyond the scope of the calibration plan are responsible for these themselves however Standard Calibration StanCal OBs are available at the telescope and from the web 4 2 The FEROS calibration unit As described in section 2 5 the FEROS Calibration Unit FCU provides internal flatfield and wavelength calibration sources The FCU is installed in the FEROS Room not mounted on the telesc
85. rogram the following trade offs have to be taken into consideration 1 4 1 La Silla Spectroscopy in the UV Visual Red regions 300 1100 nm e EMMI at the NTT TBD See http www 1s eso org lasilla sciops ntt emmi e EFOSC at the ESO 3 6 m TBD See http www 1s eso org lasilla sciops 3p6 efosc e HARPS at the ESO 3 6 m TBD See http www 1s eso org lasilla sciops 3p6 harps e CES at the ESO 3 6 m TBD See http www 1s eso org lasilla sciops 3p6 ces Spectroscopy at infrared wavelengths 1 5 um e Sofl at the NTT TBD See http www 1s eso org lasilla sciops ntt sofi FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 Lcaelle Lin EE HA Ins lt m 7 tert 97 e o 4 e 3 Fe Wage Sie en m M Dahm utt Fizn Incister Lecluncro Figure 1 1 FEROS optical system from fibre exits to detector e TIMMI2 at the ESO 3 6 m TBD See http www 1s eso org lasilla sciops 3p6 timmi 1 4 2 Paranal Spectroscopy in the UV Visual Red regions 300 1100 nm e UVES is the high resolution optical spectrograph of the VLT located at the Nasmyth B focus of UT2 It is a cross dispersed echelle spectrograph designed to operate with high efficiency from the atmospheric cut off at 300 nm to the long wavelength limit of the CCD detectors about 1100 nm To this aim th
86. rom a later night Midas 698 UNBLAZ FERO ThAr1410ext FF1212ext 1410ext Midas 699 xcorall 51Peg 1417 1212 1410 1200 enter Midas 700 plo tab 51Peg jd24 dbc If a large number of Object Calibration exposures has been obtained for one object the com mand 46 radvel objectcat objectref tharcat refthar hbin gives the possiblity to reduce all files at once For this a MIDAS catolgue objectcat with all f object extl bdf files and a MIDAS catolgue tharcat with the corresponding f thar ext1 bdf files has to be provided The catalogue names have to entered without the extension cat the FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 result table will carry the name objectcat Example Midas 0015 Midas Midas 897 gt read icat 51Peg Catalog 51Peg cat Name Ident 1212exti bdf 1417ext1 bdf 897 gt read icat 51Pegthar Catalog 51Pegthar cat Name Ident 1200exti bdf f1410ext1 bdf 899 00 radvel 51Peg 1212 5iPegthar 1200 900 gt plot tab 51Peg jd24 dbc Naxis Npix 2 4102 39 2 4102 39 Naxis Npix 2 4102 39 2 4102 39 Appendix B On line DRS filename conventions init Filename fero lt NNNN gt mt Content rawimage in FITS format as transferred to the instrument Format pixel pixel Filename FF cat Content Catalogue with FLATFIELD exposures Format MIDAS catalogue Filename ThAr cat Content Catalogue with CALIBRATION exposures Format MIDAS c
87. rvations Spectrophotometric standard stars can be used to obtain response curves of the instrument to allow a relative flux calibration of the spectra Such calibrations are obtained at the beginning of each night during Service Mode Normally telescope focusing using a spectrophotometric standard star field followed by four two minute science exposures two spectra with ADC OUT and two with ADC IN of a spectrophotometric standard can be made approximately 30mins after sunset and will thus normally finish well before the official start of the night thus minimally impacting even on Visitor Mode programmes In addition the instantaneous atmosphere telescope instrument efficiency is measured and reported by the FEROS pipeline within minutes of the exposures thus giving the observer practically instantaneous feedback on the quality of the night which can be useful for planning the rest of the night s observing Absolute flux calibrations are NOT possible with FEROS due to the diameter of the SCIENCE fibre apertures which projects to 2 0 arcsec on the sky Since the seeing at La Silla is typically 1 0 0 5 arcsec with stability over time scales of a few minutes probably no better than 0 2 arcsec one can never be certain of the fraction of light going down the fibre and hence an ABSOLUTE flux calibration is practically impossible To get the absolute level right one would need for example to do simultaneous contemporaneous photometry in order to tie down t
88. s 2 8 0 Few and faint lines in bluest orders in wavelength calibration spectra MRT CCD Cosmetic Defects s scs a cs adi saa ho or UR ss Preparing the Observations UE Cra A Roe ee kk hook XO RI We RD eum BOR ONES ONG RUE eret 3 2 FEROS instrument modes and basic choices 22s 3 2 1 The Object Sky Configuration 2 22 3 22 The Object Calibration Configuration 3 3 Introducing Observation Block 3 4 The FEROS Exposure Time calculator 2 22e 2 41 Definition of the target s so se rastas RR ARR Re ER ee a hoo 3 5 Target Acquisition and Guiding os 6 c o yo ee ER a 3 6 Computing time overheads for your program dor AI 10 10 13 13 16 16 17 18 18 18 19 19 19 20 20 vi St Bi 1 ee FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 The calibration of FEROS data AT The FEROS Calibration Play o lt scs pk ow du Roo OR Gow eR de di 42 Whe FEROS calibration uM cos 79km 3k RR RO m RC ROSEO QE IR ee ens 4 3 Calibration in wavelength dal Fla telde 22056 eT a RS Re AEN echo aO er GP cR y t ee 4 5 Soler spectra ve s ce a4 oic a A 3X 9 38 3 3 RS RES Wo a X X ox 4 6 Flux standard star observations soo soe ees Ar QU Canines undue ge se Be a Be ee ee EUR wr ee e donee Sree x 4 8 Special calibratione s eon oe opm be pe RR RR RR mL Ea ded AS e 4 8 1 Use of reference stars to correct for fringing or atmospheric lines Observing 5 1 Before the observing nights preparation of
89. so org lasilla sciops 2p2 E2p2M FEROS DRS 6 3 Off line data reduction Any echelle data reduction package under MIDAS IRAF or based on IDL can be easily adapted to extract and calibrate FEROS data MIDAS has a dedicated context feros This is the same pipeline run at the telescope though the latest version of the user procedures should be obtained Isince November 2005 36 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 37 from the La Silla FEROS DRS web page http www ls eso org lasilla sciops 2p2 E2p2M FEROS DRS Various parameters and techniques can be applied to improve the quality of the reduction over that typically achieved at the telescope Most recently on the 1 of November 2003 the content of the FEROS FITS image header records were complete revised and due to the change over from the Copenhagen University BIAS CCD controller system to the ESO standard FIERA CCD controller system l he standard version of the FEROS DRS user procedures as provided by any standard MIDAS installation do not know how to cope with these changes The version of these procedures provided at the La Silla FEROS DRS web pages see above is specifically intended to be able to cope with data from all epochs of FEROS s history from the original BIAS system installed at the ESO 1 52 m telescope to the slightly modified BIAS system as originally installed at the MPG ESO 2 20m telescope to the current FIERA based system I
90. termines the wavelength interval to be used for the SNR estimate fibrenum refers to the fibre to be used i e 1 for the object fibre default 2 for the sky fibre Note that the performance of this procedure is heavily affected by sharp spectral features as spectral lines or cosmic ray hits Further the SNR of the used flatfield may limit the SNR measured A 6 4 Spectrograph focus test After a wavelength calibration spectrum fero lt NNNN gt mt has been taken and the DRS is initialized as described above the command 00 focus lt NNNN gt reduces the calibration spectrum measures the FWHM of the emission lines and plots the FWHMs over the position in dispserion direction A FWHM of 2 2 pixels corresponds to a resolving power of R 48 000 A 6 5 System efficiency test After a spectrum fero lt NNNN gt mt of a standard star has been taken and the spectrum has be passed the automatic standard reduction the command efficiency lt NNNN gt standard star flux table computes the efficiency of the instrument including the telescope fibres and the detector as function of the wavelength The flux tables of the standard star must be available in the subdirectories of midas calib data spec and have to be given with the subdirectory e g as ctio hr9087 A 6 6 Radial Velocities by Cross Correlation Radial velocities with high precision can be obtained in the OC mode of FEROS The on line DRS provides a very simple cross correlatio
91. the last exposure of the template and it is the last templat of the OB then the command average_cat ThAr cat followed by init ThAr lt MMMM gt flat 0 85 are run automatically adds the incoming ThAr Ne files to the catalogue ThArNe cat SCIENCE adds the incoming file to the catalogue Objects cat start the pre reduction of the the file 0 prered lt NNNN gt raw_image where raw_image is the name of the inputfile for the following on line reduction computes the barycentric velocity according to the telescope position and writes the result to the descriptor BARY CORR FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 41 computes and subtracts the interorder background of the echelle spectrum BACK FEROS straightens the echelle orders STRAIGHTEN FEROS extracts the echelle orders EXTRACT FEROS removes the blaze function and the pixel pixel variations UNBLAZE FEROS rebins the echelle orders to wavelengths REBIN FEROS according to beforehand deter mined dispersion coefficients In this step also the barycentric correction is applied merges the echelle orders MERGE FEROS into two 1D spectra named f lt NNNN gt 1 and f lt NNNN gt 2 where the spectrum with the ending 1 referes to the spectrum recorded on the object fibre and the spectrum with the ending 2 to the spectrum recorded on the sky calibration fibre Image catalogues listing fero lt NNNN gt mt files in the MIDAS working directory can be reprocessed with the
92. tification of target acquisition requirements e g finding charts offset star e Preparation of needed Observation and Calibration Blocks Part of the observing time at the MPG ESO 2 20 m telescope is carried out in service mode by the Observatory Staff i e in absence of the applicant All information necessary to successfully execute the proposed observing program has to be provided in the form of Observation Blocks finding charts and other relevant information in advance of the observations to ESO following the instructions sent to the applicants The Observatory staff will combine the execution of different 21 22 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 programs in the same night optimizing the time sequence and the seeing and moon requirements Observations carried out with the applicant present at the telescope are referred to as visitor mode observations In this mode the astronomer prepares or finalizes the OBs at the Observatory in advance of his her nights He she decides about the sequence of observations during the night but their execution is however still performed by the telescope and instrument operator TIO To facilitate the preparation of Phase I and Phase II proposals besides the information provided in this User Manual ESO has developed a sophisticated Exposure Time Calculator ETC see Section 3 4 The ETC permits to estimate the signal to noise ratio for a given configuration and exposure t
93. trolled The telescope and instrument operator TIO carries out the observations and is responsible for the checking that the telescope and instruments perform correctly the main area of responsibility of the visiting astronomers is the selection of the OBs to be executed based on the sky conditions and on the results of the previous observations The main actions are outlined below 5 2 1 Target acquisition The OB to be executed is loaded to the BOB panel and started The Telescope Control Software TCS reads the target coordinates from the OB and the telescope is pointed Once the telescope has completed the pointing the FEROS Fibrehead Viewer FFHV Camera which images the fibrehead produces an image of the target field 6 x 4 arcmin as reflected by the fibrehead can be used for the final step of target acquisition The FFHV images are properly oriented in the sky and Remote Integrated Telescope Zentrum The MPG ESO 2 20 m telescope the ESO NTT telescope and the ESO 3 60 m telescope 34 FEROS II User Manual 78 0 2P2 MAN ESO 90100 0008 35 the coordinates which can be read with the cursor are converted to sky coordinates The target coordinates entered in the OBs have to be accurate to better than 1 to avoid unnecessary waste of telescope time in the identification process The image of the FFHV field is automatically saved at the end of the acquisition The telescope pointing rms accuracy is of the order of 5 arcsec
94. up for 5mins and the wavelength calibration lamps are warmed up for 1min before being used If FFs are to be acquired during the night then it depends on their intended purpose If they are to be used for obtaining an instantaneous tracing of the orders then no warmup is required If on the other hand they are intended to check the instantaneous FF response then a warmup will be required in order to have the lamp reach stable operating conditions For calibrations made during the night a warmup for the wavelength calibration lamps can probably be safely skipped The read out time for the CCD 1 port is fast high gain unbinned read out mode 225kHz 1 low 1x1 41 seconds slow low gain unbinned read out mode 60kHz 1 high 1x1 148 seconds The shortest possible cycle time with the FEROS instrument can be achieved by the use of the ultrafast medium gain unbinned read out mode 625kHz 1 med 1x1 21 seconds However this readout mode has NOT yet been fully commissioned It should therefore be considered experimental and is offered in Visitor Mode only where it will be the responsibility of the visitor to verify the scientific integrity of the resulting data e Calibrations BIAS frames and FF ThArNe and ThAr Ne calibration lamp exposures are taken during the day see section 4 1 If wavelength accuracy is critical either the OBJCAL mode should be used or a ThAr Ne or ThArNe calibration should be taken immediately after the scienc
95. users who are not familiar with the FEROS instrument and who are interested in a quick overview of its capabilities in comparison with other similar ESO instruments This should enable a potential user to select the best instrument for a given observing program It also includes information on how to access FITS files of reference FEROS spectra and a glossary of terms used in the Manual The second Chapter provides the description of the instrument the instrument layout 82 1 its components 2 2 the properties of the CCD Fibrehead Viewer and of the scientific CCD detector 8 2 3 2 4 the Calibration Unit and the FEROS WFI Adpater 82 5 2 6 the spectral coverage resolving power and overall efficiency 82 7 and reference to instrument features and known problems to be kept in mind while planning the observations or reducing the data 82 8 It can be consulted by users who want to prepare an Observing Proposal Phase I but should definitely be read by those who have been granted observing time and have to prepare their observations Phase II The third Chapter provides the basic information needed to prepare an observing program the identification of the instrument observing modes 83 2 and a description of the Exposure Time Calculator 83 4 The fourth Chapter deals with calibration strategy wavelength flat fielding relative and absolute calibrations of data obtained in standard operation The fifth Chapter provides information for th
96. word FLAT IMG e Standard reduction of the wavelength calibration BACK FEROS STRAIGHTEN FEROS EXTRACT FEROS The name of the reduced calibration is found in the keyword WLC IMG e Search for emission lines in the reduced calibration frame FIND FEROS e Wavelength calibration by iterative fitting of the dispersion coefficients CALIBRATE FEROS The residuals of the individual lines are plotted over the order number The spread should not exceed a peak to peak of 0 02 Angstroms e The session parameters are saved as session WLC IMG With this step completed the FEROS on line DRS is initialized Every new incoming spectrum will be saved and reduced now as described above A 5 On line Reduction Options During the Night The context keywords allow to control the parameters of the reduction process The keywords can be listed together with their current contents by the command SHOW FEROS and are set with the command SET FEROS key value Alternatively the keywords can be set using the FEROS GUI which is started by the command CREATE GUI feros If the keywords are set to new values they will only affect the automatic on line DRS for next incoming files If one of the files already transfered to the IWS fero lt NNNN gt mt should be reduced again according to the new settings of the keywords this is easily achieved by re starting the G autoreduce command manually as follows autoreduce fero lt NNNN gt Useful keywords for th
97. y Cross Correlation 2 0 0 ee ee On line DRS filename conventions Naming convention for DRS products Data Archiving The FEROS FITS header Acknowledgements 34 34 34 34 35 35 36 36 36 36 38 38 38 38 39 39 39 Al Al 42 43 43 43 44 44 44 44 47 52 53 54 60 FEROS IT User Manual 78 0 2P2 MAN ESO 90100 0008 vii This page was intentionally left blank Chapter 1 Introduction This is the FEROS User s Manual It is primarily intended as the main reference for observers who wish to use or have been awarded time to use FEROS in either visitor or service mode 1 1 On the contents of the FEROS User Manual The current version of the FEROS User Manual is available as retrievable postscript and PDF files from the ESO home page on the World Wide Web http www ls eso org lasilla sciops 2p2 E2p2M FEROS Before the observing proposal application deadlines the User Manual is normally updated any signif icant changes are announced on the FEROS webpages If you have no access to the WWW a printed copy can be requested from ESO s Visiting Astronomers Section on Internet visas eso org in Garching Germany Paper copies of a new version of the FEROS User Manual are printed out only after a major revision of the document The reader is referred to the web version of this document for the best quality of the included color figures The first Chapter of this manual is addressed to
98. y special constraints needed time critical observations etc 5 Define calibration needs over and above the standard calibrations as defined in the calibration plan 6 Compute time to be requested including overheads Chapter 4 The calibration of FEROS data 4 1 The FEROS Calibration Plan The observatory s calibration strategy for the FEROS instrument is summarised at http www ls eso org lasilla sciops 2p2 E2p2M FEROS CalPlan Table 4 1 provides a summary of the calibration plan as at the time of this writing Nov 2005 for scientific FEROS data A minimum set of calibrations see below are acquired each afternoon in both the 225kHz 1 low 1x1 and 225kHz 1 low 2x2 readout modes as part of the Daily Health Check More extensive sets of calibrations see below are semi automatically acquired each morning daily according to the science data obtained in the previous night The same calibrations are applicable for both OBJSKY and OBJCAL mode If additional calibrations are needed the corresponding Observation Blocks have to be provided by the Visitor observer or the Service mode PI using the data and instructions provided in the following sections In a nutshell the FEROS Calibration Plan provides for the acquisition of daytime calibrations in the afternoon before and the morning after each night s observations Each afternoon a Daily Health Check OB which allows the verification of the basic health of the instrument as well as in

Download Pdf Manuals

Related Search

Related Contents

Mobiflex 200-M - Lincoln Electric  Samsung HT-D350 Наръчник за потребителя  Manual - Advantage Controls  TASER CAM™ - Fortress Tactical  ドーム型防犯カメラ 取扱説明書  Manual, Slide & Remote Control Installation and User  C D A B    

Copyright © All rights reserved. Failed to retrieve file