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HIRES USER`S MANUAL - WM Keck Observatory

1. UE 14 Cross Disperser C Dy 18 cee Poet Ce eR 19 Cortector LENSES ooa A Cl decidat 20 Primary een dit uisi cess 20 Field Plattener Dewar Windows s asia optata oet ea AUNT 20 ied Glo cad ta ge ere Geena 21 Dewar GE Me e 22 Enclosure Electronics Bay and Clean Room Ante Chamber 22 Electronics Control System sete ieie i 23 Software Control Gp eu 24 Chapter 3 The HIRES Spectral Format 5 25 Section 1 Before starting some words about Con guration Files 26 Section 2 Starting the format Simulator eese 27 Section 3 Graphical inne 29 Modifying the display 30 Section 4 Command Line Interaction 34 Chapter 4 Preparation for 34 ii List of Figures Figure T HIRES Schematic 4 Table 1 TV Sli DT 6 Figure 2 TV Camera Field irte See tec P LOU 7 F
2. hn esos paws h eser sesso h esses 11080555 rele a wree 2 eus s vus D peos 0005 ao 2 ees 2 fosos 30600 2o oos uwexs bear responsibility for choosing the correct combination of blocking filters and may have to refer to lter transmission curves In particular real filters do not have in nitely sharp cut on curves and this can make a difference in some cases However as a rst cut guide to selecting appropriate filters the following table lists some useful combinations Figures 3 and 4 show the transmission of the various HIRES filters provided for order blocking Note that different combinations of filters require refocusing of the collimator and this refocusing is now handled automatically whenever new filter combinations are selected The focus change will be approximately T 3 where T is the total thickness of all filters in 13 HIRES Manual Instrument Description the beam Adding filters requires moving the collimator farther from the slit by a distance T 3 All Schott filters in Filter Wheel No 1 are 3 mm thick The CuSO4 filter is 5 mm thick The OCLI detector trimmer d t is 0 533 mm thick All Schott and CuSO4 filters have been AR coated with an optimized multi layer broad band overcoat
3. Field Flattener Dewar Window The field flattener is a thick meniscus lens made of Corning 7940 fused silica As with the corrector lenses it is AR overcoated with sok gel so must never be touched at any time with anything for any reason period This lens also functions as the dewar vacuum window It is sealed to the dewar with a single o ring and positioned axially by a precision machined surface Radial locating is accomplished with three radial retainer clips The lens must be properly centered to within 0 02 A light shroud around the edge of the lens helps to keep the CCD reasonably dark but is not completely leak proof A slow operating dark cover consisting of a cap which moves into place over the field flattener helps to keep fingers and other foreign invaders away from the sol gel surface of the lens and provides some protection from flashlights or other low level lighting used by personnel entering the room Again this dark cover is not 20 HIRES Manual Instrument Description expected to be completely light proof so care should be taken when entering HIRES to avoid using any more photons than necessary unless one is prepared to suffer potential image afterglow effects And the dark cover should always be put back into place when the system is not in use to provide maximum mechanical and dust protection for the sok gelled lens Detector We will be using the engineering grade CCD from the LRIS instrument at rst light
4. Exposure Control Shutter During observing the CCD is normally left open to the room Its darkcover is a relatively slow mechanism intended primarily to protect the sol gel coating on the field flattener Timing of exposures requires a much faster mechanism so starting and stopping of exposures is controlled by a fast shutter behind the slit This shutter is actuated by a signal from the CCD controller crate The minimum exposure time is 1 second Collimators The f 13 7 beam is collimated into a 12 diameter beam by either of two identical collimators These collimator mirrors are spherical with matched radii and tilted by 1 75 such that the beam is reflected up towards the echelle at an angle of 3 5 One of the collimator mirrors has an enhanced 2 layer dielectric over aluminum coating and is for use over the 0 3 to 0 5 micron spectral region This is called the Blue collimator The other collimator is coated with an enhanced silver recipe the holy grail and features somewhat higher reflectivity in the 0 34 to 1 1 micron range but drops off sharply below 0 34 microns This collimator is called the Red collimator Figure 5 shows the reflectivity s of both collimators Echelle The echelle is a mosaic of 3 of the largest echelles currently available The mosaic is 12 by 48 in size The ruling is 52 68 grooves mm and the blaze angle is 70 5 The collimator to camera angle 22 is 10 0 The echelles are intentionally pistoned in
5. Check the locations of these araes yourself to see that things are where you expect them You don t need le names for zero dark at etc since these les will already have the correct IMAGETYP FITS header keywords and the routine will be smart enough to recognize them as such For this example we will be tting the overscan region interactively using a cubic spline So before moving on let s summarize what we are now about to initiate when we g out of this parameter list We are set up to do overscan correction bias zero frame correction and dark current correction of each object image note that we are including our quartz and our thar images as object images which dso need correcting The images will also be trimmed of their prescan and overscan regions When happy with the set up type g which will send you onward Note if IRAF has some trouble locating or otherwise deciding upon correct image types for your data les it may well return immediately to the command line prompt without actually doing anything nor telling you that it didn t do anything The processing will take a while so if it returns immediately something is probably wrong If all is well IRAF will begin trimming the frames and extracting baseline information Since we speci ed interactive baseline tting it will put you into the interactive baseline tting mode for each frame Try playing with the baseline tting from the tektronix plot wind
6. HIRES Manual Instrument Description Two 8 position filter wheels are also provided at the CCD TV for brightness and color control One wheel contains neutral density filters while the other contains colored glass filters Table 1 shows the available ND and colored filters for the TV The neutral density filters in combination with the TV lens aperture stop control and tv integration time give the camera some 20 stellar magnitudes of dynamic range The color filters provide some capability for distinguishing and or guiding on different color sources For example a colored filter may be necessary for accurate guiding if the wavelength being sampled by the spectrometer is not the same as that sensed by the CCD TV In particular the Photometrics CCD is not sensitive below about 0 4 microns so ultraviolet spectral observations require special offset guiding especially if significant atmospheric dispersion is present Table 1 TV Filters 03 3 The aperture and focusing of the TV camera lens is also under computer control The aperture is generally to be left wide open but can be stopped down to increase the dynamic range of the camera Re focusing will be necessary as one switches from guiding off the slit jaws to guiding off the decker plates Some refocus is also necessary if different total thickness filter combinations are used The TV camera system automatically refocuses for the different filter thickness combinatio
7. Y label position fraction of mean sysid yes Include system banner and step value yscale yes Draw Y scale title u vogt IRAF demo solar final ec imh Plot title xlabel wavelength X axis label ylabel intensity Y axis label xmin INDEF X axis left limit xmax INDEF X axis right limit ymin 0 Y axis bottom limit ymax INDEF Y axis top limit logfile Logfile graphic stdgraph Graphics output device cursor Cursor input mode ql If you set fractio 0 the continuum level for all orders will remian at a constant ordinate value all the way across the spectrum plot The spectrum will be very highly compressed in the wavelength direction but can be expanded about any point with the lt wx gt command as many times as you need and then lt wl gt and lt wr gt to pan left and right Unfortunately there doesn t seem to be an unexpand key stroke so you have to lt wa gt to redraw the entire plot if you ve overexpanded or get tired panning left right in too small increments It is instructive to look carefully at the order overlap regions to see how well these overlap regions agree These are independently observed and reduced spectral regions and offer a useful consistency check Some disagreement is expected in the continuum level because it is very hard to rectify the continuum of each echelle order right near the near the ends of each order splines have a way of heading off on their own at the end of a data
8. 0 at typical resolutions of 30 000 to 80 000 A discussion of the various key science drivers which weighed heavily in the design of HIRES can be found in the HIRES Phase C proposal Vogt 1988 and will not be discussed here A preliminary overview of the as built instrument was published by Vogt 1992 HIRES is a fairly standard configuration in plane echelle spectrograph with grating cross dispersion It resides permanently at the right nasmyth focus of the Keck telescope HIRES is designed primarily to go quite faint by traditional high resolution spectroscopy standards on single objects and to give a relatively large throughput or slit width times resolution product without the need in general to image slice at the entrance slit The nominal throughput of HIRES is about 39 000 arcsecs which means that a 1 arcsec entrance slit yields a resolution of about 39 000 It achieves this relatively large throughput in spite of the very large diameter of the telescope primary by a combination of a large 12 diameter collimated beam a large 48 long echelle grating mosaic and very fast f 1 0 exquisitely achromatic camera The optics and image quality are optimized for use over the entire 0 30 to 1 0 micron spectral region without refocus and could readily be extended to 2 0 microns by replacing the optical CCD with an IR array detector A generous amount of room has intentionally been left between echelle
9. 46 HIRES Manual Instrument Description dispersion fitscat yes Fit scattered light interactively fitsmoo yes Smooth scattered light interactively line 900 Dispersion line nsum 10 Number of dispersion lines to sum buffer 1 Buffer distance from apertures apscat1 Fitting parameters across the dispersion apscat2 Fitting parameters along the dispersion mode ql Note that we ve set all the nd recenter resize edit and trace aperture parameters to no since we will be using the apertures found from the quartz spectrum The line 900 was set to try to avoid the dark blob but the routine started anyway at column 1024 so this didn t seem to matter It will start by giving you a cut down column 1024 Identify what you think are the scattered light points and t them interactively using order low high and niter commands to adjust the order the low and high reject threshholds etc In general you ll want to set the high threshhold pretty low to reject high points which come from edges of orders etc And you ll want to set the low threshold pretty high so as not to reject many low points because most of them will contain useful dark information Again try to stay with as low an order as you can to avoid introducing ripples When satis ed with each column s t type to quit and you will be prompted for a new column value You must reply with a col 100 to t along column 100 etc I suggest tt
10. Astronomy Observatories Tucson Az Vogt S S 1992 ESO Workshop on High Resolution Spectroscopy with the VLT ESO Garching 11 13 February 1992 223 Vogt S S 1988 HIRES Phase C proposal UCO Lick Technical Report No 57 Willmarth D 1987 A CCD Atlas of Comparison Spectra Thorium Argon Hollow Cathode 3180 A 9540 A F National Optical Astronomy Observatories Tucson Az Appendix A Some useful numbers This section not yet completed Appendix B Spectrograph Technical Data This section not yet completed Appendix Detector Technical Data This section not yet completed Some items for potential inclusion format at led response dark current cosmetic defects noise and gain full well capacity cosmic ray rate orientation and useful ampli Appendix D Telescope Technical Data 25 HIRES Manual Instrument Description This section net yet completed Some items for potential inclusion Effective light gathering area Image scale at f 15 nasmyth 1 3789684 arcsec mm at nasmyth see p 6 5 of HIRES book V of 4 30 92 notes Typical pointing accuracy Typical guiding accuracy Zenith blind spot limits 1 1 Altitude limits 33 3 nasdeck region 5 3 to 146 2 azimuth 15 elsewhere dome shutter starts vignetting Field rotation at nasmyth yes indeedy Appendix E Tables of Spectral orders FORMAT IN FIRST ORDER OF THE CROSS DISPERSER ECHELLE grooves mm 52 68 Blaze A
11. Dick Kanto and Jim Ward did the mechanical fabrication Bill Brown assisted with optical coatings Lloyd Robinson and Mingzhi Wei developed the CCD detectors Marlene Couture and Joe Calmes did the accounting with Ted Cantrall providing help with the project scheduling and purchasing 63
12. Na D etc ended up with accurate wavelengths In splot use the lt gt and lt gt keys to move among the orders and lt wx gt lt wl gt and lt wr gt to expand in x and move left and right around any feature You ll see that you have a pretty decent looking spectrum at this point but that there is still the strong echelle blaze pro le dominating the continuum shape We will remove that in the next section Flattening the Continuum To atten the continuum we will use the task continuum We will use solar ds ec imh as the input and save the continuum attened version as solar nal ec imh Here is the parameter le IRAFImage Reduction and Analysis FacilityPACKAGE echelleTASK continuum input solar ds ec Input imagesoutput solar final ec Output images lines Image lines to be fit type ratio Type of output replace no Replace rejected points by fit wavesca yes Scale the X axis with wavelength logscal no Take the log base 10 of both axes overrid no Override previously fit lines listonl no List fit but don t modify any images logfile logfile List of log files interac yes Set fitting parameters interactively sample Sample points to use in 52 HIRES Manual Instrument Description fit naverag 1 Number of points in sample averaging functio spline3 Fitting function order 1 Order of fitting function low_rej 2 Low rejection in sigma of fithigh 0 High rejection in sigma of fit niterat
13. about 4800A and ends near 6000A The absorption spectrum thus yields a very stable zero velocity reference spectrum superimposed on the spectrum of the object being observed It is intended to be used primarily for very accurate radial velocity studies involving asteroseismology and searches for planetary companions of stars A detailed description of the iodine cell and its use for ultra precise radial velocity work can be found in Marcy and Butler 1992 Decker Tray and Deckers Immediately above the slit is a tray containing a series of 4 decker plates These decker plates are highly reflective for guiding and made of type 420 Stainless steel which were EDM d to shape and then polished in the UCO Lick optical Lab These deckers define the length of the effective slit seen by the spectrometer Some of the deckers in plate A define slit length only while others define both slit length and width As such these latter deckers are to be used without the underneath slit i e the slit gets opened up wide so it is out of the way They may be more effective for guiding on faint objects since there is then only a single focal plane whereas using the deckers in plate A in conjunction with the slit results in two slightly separated focal planes with some resulting corruption to the reflected guide image If one is using a decker which also de nes slit width i e spectral resolution and wavelength zero point one must bear in mind that wavelength zero
14. have all the necessary les read in and converted IRAF imh les with appropriate names and keywords you are ready to begin the actual data processing The rst step is to inform IRAF what instrument set up con guration you are using and get it loaded Type setinstrument to load the setinstrument package for HIRES You will be asked the question Instrument ID type for a list hires Assuming it is the HIRES instrument le you will be using hitting a simple lt return gt will load the default option hires and then move you onward to the ccdred task in the imred package You will not see the parameter list for setinstrument but it can of course be accessed by epar ing on setinstrument It looks like this Image Reduction and Analysis FacilityPACKAGE ccdredTASK setinstrument instrume hires hstrument ID type for a list site keck Site ID directo ccddb Instrument directory review yes Review instrument parameters query Instrument ID type q to quit mode ql CCDRED You are now in the epar mode in the parameter list for the package ccdred This is what you ll see Image Reduction and Analysis FacilityPACK AGE imredTASK ccdred pixelty real real Output and calculation pixel datatypes verbose yes Print log information to the standard output logfile logfile Text log file plotfil Log metacode plot file backup Backup directory or prefix instrum ccddb keck hires dat CCD instrument file ssfile subset
15. in the reductions For example quartz s might be labelled quartz1 quartz2 etc Darks of various exposure times might be called dark100s dark500s etc Try to stick with short names to minimize typing and keep names fairly distinct so that you can make most use of command line interpreters when wild carding to again save typing You should now start up from a separate xwindow the SAOIMAGE tool The reason we start this up from a separate xwindow is because it sends text at you from time to time and it is annoying to have that chatter break in on your IRAF text Now from a different xterm window than the one you used to start up SAOIMAGE move into your IRAF directory and type lt cl gt to get IRAF going Then cd into the demo subdirectory where the images are I don t understand why you can t just start IRAF from this demo subdirectory but that s ok for now Reading FITS les into IRAF The very rst task is to get your FITS les read into IRAF as imh les Get into the parameter editing mode of the r ts task by typing epar r ts This is what you will see IRAFImage Reduction and Analysis FacilityPACKAGE dataioTASK rfits fits_fil solar fits quartz fits thar fits dark fits zero fits FITS data sourcefile_lis 1 File listiraf_fil solar quartz thar dark zero IRAF filename make_im yes Create an IRAF image long_he no Print FITS header cards short_h yes Print short header datatyp ushort IRAF data type blank
16. pixel datatype keeplog _ keeplog Keep log of processing logfile _ logfile Log file imlist tmp ims7334a Gmfd tmp ims7334a input flat flat flt flat mode ql Note that atten will write the at elded images back over the originals so if you want to go back to un attened solar imh and thar imh you will have to imdel these les and r ts in both solar ts and thar ts again It is also a good sanity check now to display the newly attened solar and thar They should look clean with nice dark spaces between orders and perhaps a bright line along the edges of each order Note that they have only had the high frequency pixel to pixel variations removed at this point and will still show the low frequency blaze variation in intensity That will be removed later It is also humbling and scary to roam around a bit on the histogram equalized thar frame searching for ghosts You ll see a number of them as well as the meteor Removing scattered background light The next task is to measure and remove the scattered background light This is light which shows up between the orders and which results from scattered light ghosts and other re ections inside spectrograph You will use the task apscatter in the echelle package of routines so bye out of the generic package if you aren t already out and get into the echelle package now Basically apscatter will allow one to interactively t a function
17. point will change if the decker tray slide which moves perpendicular to the slit axis is repositioned Thus one may expect to have to take new wavelength calibrations if the decker tray is repositioned while using such deckers Also the collimator mirror must be refocused when using deckers only rather than deckers slit since the decker plane is about 3 16 above the slit plane The instrument control system automatically refocuses the collimator for the particular slit decker filter thickness collimator mirror combination used Table 3 shows the complete selection of available deckers HIRES Manual Instrument Description Table 3 HIRES Deckers Projected Projected Height Width height width Comments arcsec pixels pixels fo 1046 00000 pe 8 e sky B3 14 0 0 574 73 2 2 00 R 60 000 14 for sky sky U E E E 5 12 10 HIRES Manual Instrument Description Table 3 Continued HIRES Deckers Projected Projected height width Comments pixels pixels sky sky C2 14 0 0 861 73 2 3 00 R 45 000 14 for sky dU 2222 3 C4 3 5 1 148 18 3 4 00 R 34 000 3 5 a sky d Eu c D4 14 0 1 722 73 2 R 23 000 14 for sky 05 0 119 0 179 0 623 0 624 projects to 15x15 microns for tests Slit The slit is a b parting mechanism which means that the slit centroid should not change position as
18. set But the shapes and relative depths of all spectral features should match very closely if everything has been done properly 53 HIRES Manual Instrument Description Once you have a view of some piece of the spectrum you like you can get a hard copy by simply typing snap If you are correctly set up in the system this should output the hardcopy directly to the local laser printer That brings us to the end of our initial foray into IRAF data reduction of HIRES spectra You are now no doubt well aware that this was only a very simple but entirely respectable shot at reducing a data set IRAF is a very powerful data reduction environment with lots of rooms and corridors to explore Data sets which push the limits of dark current cosmic ray exposures low S N etc may require more calibration frames and more extensive reduction treatments Chapter 7 HIRES Exposure Estimator An exposure estimating program rst written by UCSC graduate student Don Penrod and later enhanced by UCSC graduate student Michael Keane is available to help the user estimate signal to noise under various conditions This S N estimator is fully self prompting and very easy to use It knows about the overall ef ciency of the telescope and spectrometer It also includes provisions for calculating slit losses under various seeing conditions absorption by the atmosphere at any input airmass and effect of moonlight on sky background subtraction This program resi
19. the mosaic such that the two gaps are maximally shadowed minimizing light loss at the gaps The echelle mosaic alignment is intended to be passive and should never need adjustment Alignment is maintained by clamping the echelles to a large granite subplate minimally constrained so as not to intro duce any moments or unwanted forces The mounting scheme is intended to be 14 TRANSMISSION HIRES Manual Figure 3 Blue Blocking Filters wG36d KV370 WAVELENGTH microns 15 Instrument Description Instrument Description HIRES Manual Figure 4 Red Blocking Filters Detector trimmer s s 1 3 M 5 e NOISSINSNVMS WAVELENGTH microns 16 REFLECTIVITY HIRES Manual Instrument Description Figure 5 Collimator Re ectivities red collima enhanced tor silver blue collimator 2 layer enh anced Al 0 3 0 4 05 06 07 WAVELENGTH microns 17 08 0 9 1 0 1 1 HIRES Manual Instrument Description thermally insensitive provided the environment is isothermal i e it will remain aligned at any temperature provided the temperature is stable The echelle is mounted in a precision rotation stage Rotation of the stage allows the echelle form
20. the thar imh for scattered light since I will only use it for wavelength calibration anyway Here is the parameter le for this Image Reduction and Analysis FacilityPACKAGE echelleTASK apsum input solar ds thar List of input images output List of output spectra format echelle Extracted spectra format referen quartz List of aperture reference images profile List of aperture profile images 47 HIRES Manual Instrument Description interac yes Run task interactively find no Find apertures recente no Recenter apertures resize no Resize apertures edit no Edit apertures trace no Trace apertures fittrac no Fit the traced points interactively extract yes Extract apertures extras no Extract sky sigma etc review yes Review extractions line INDEF Dispersion line nsum 10 Number of dispersion lines to sum backgro none Background to subtract nonelaveragelfit weights Extraction weights nonelvariance pfit fitld Profile fitting type fitldlfit2d clean no Detect and replace bad pixels skybox 1 Box car smoothing length for sky saturat INDEF Saturation level readnoi 0 Read out noise sigma photons gain 1 Photon gain photons data number lsigma 4 Lower rejection threshold usigma 4 Upper rejection threshold nsubaps 1 Number of subapertures per aperture mode ql By not putting explicit names in the list of output spectra we will be accepting the defa
21. tipped slightly such that the collimator could also act as the camera and produce an image up near the slit This image could be picked off by a small mirror and sent to a detector mounted up near the slit Finally HIRES can also be extended out through the future expansion door in the wall near the cross disperser A symmetrical outrigger could be added to the optical bench structure and the cross disperser used to steer the light to perhaps a different focal length camera Image rotator Atmospheric Dispersion Compensator Image slicers or adaptive optics tip tilt system Appendix I Acknowledgments HIRES was built by a superb team of people at UCO Lick Observatory Former UCO Lick director Bob Kraft and present director Joe Miller contributed much useful scienti c technical and managerial input Neal Jern was the overall project manager Jack Osborne and Bruce Bigelow were the mechanical engineers Harland Epps did the optical design optimization Carol Osborne assisted with drafting Master Optician Dave Hilyard did the optical fabrication with help from opticians 62 HIRES Manual Instrument Description Darrie Hilyard and Gerard Pardeilhan Terry Ricketts did the electronics design Lance Bresee and Cal Delaney assisted with the electronics fabrication and checkout Bob Kibrick Richard Stover Al Conrad Dean Tucker Steve Allen Kirk Gilmore and Mike Keane provided software support Erich Horn Jeff Lewis Terry P ster
22. using to the interorder light both in the row and column directions This 2 4 functional t to the background is then subtracted from the given image Note here that scattered light will depend strongly on the illuminating source and thus each individual data frame will have different scattered light characteristics Furthermore features like the meteor would require quite high order to t accurately and may be quite tricky to remove In many cases it may be better depending on the data and application to simply steer clear of the regions contaminated by the meteor So here is the parameter list for apscatter set up to use solar imh as the input quartz imh as the reference image for the apertures and to write the output as solar ds imh solar de scattered Note that we are again getting our aperture information from the quartz image Image Reduction and Analysis FacilityPACKAGE echelleTASK apscatter input solar List of input images to subtract scattered lightoutput solar ds List of output corrected images scatter List of scattered light images optional referen quartz List of aperture reference images interac yes Run task interactively find no Find apertures recente no Recenter apertures resize no Resize apertures edit no Edit apertures trace no Trace apertures fittrac no Fit the traced points interactively subtrac yes Subtract scattered light smooth yes Smooth scattered light along
23. very difficult to re do They can be cleaned by a high pressure ethanol spray but only after removing from their cells and by qualified technicians These coatings also have 35 times the surface area of the part they are on so they are a very effective magnet for dust Thus their covers must be kept closed as much as possible and the HIRES enclosure must be periodically wiped down for dust Hextek Primary Mirror The camera mirror is a 44 diameter f 0 76 sphere It is fabricated from a lightweighted mirror blank manufactured by Hextek Corp in Tucson Az The mirror blank weighs only about 183 Ibs It is supported axially at 6 points which attach to the mirror s honeycomb structure at the center of gravity plane Radial support is accomplished through a diaphragm ring structure glued to the center rear surface of the mirror The mirror is enclosed in a dust tight housing and its doors should be kept closed whenever possible for obvious reasons Eventually two identical mirrors will be available one overcoated with enhanced aluminum and the other overcoated with a multilayer silver recipe At present only a single mirror is available overcoated with a standard telescope grade aluminum coating Switching between mirrors or removing the one presently available mirror is done with a manually operated overhead crane The mirror cell assembly is kinematically located on three ball feet and held in place by both gravity and hold down clamps
24. 0 Blank value scale yes Scale the data oldiraf no Use old IRAF name in place of iraf_file offset 0 Tape file offset mode ql On the rst line for 265 91 enter the names of les to be read in I ve already typed in the ts 21 and iraf 21 lines for you These lenames will all be entered on one line with commas and no spaces between names They solar ts quartz ts thar ts dark ts zero ts Using the same sequence of names for iraf 71 parameter will give the IRAF les the same names but the extension will imh I like to do it this way to avoid getting confused with renamed les It is also very important that the datatyp parameter be set to either ushort unsigned short or real and that the scale parameter be set to yes Once nished type lt g gt to exit and execute You may now wish to check your directory to see that all the corresponding imh les have been created You might also want to check your disk space with a df gt to make sure you have enough room to keep going Once data les are read in with r ts and converted to imh les each imh will actually be carried around as both a header le imh and a corresponding pix pixel le i e where all the pixel information is kept The pixel les live in a 38 HIRES Manual Instrument Description directory speci ed by the logical variable imdir In my setup imdir is set to HDR pixels This setup puts the pixe
25. 1 718 13 839 42 764 38 26 1 1589 4004 3 45 0 1 756 14 152 44 500 38 69 1 1688 4049 8 46 0 1 795 14 476 46 276 39 13 1 1887 4096 4 47 1 1 836 14 810 48 091 39 58 1 1986 4144 0 48 2 1 878 15 157 49 948 40 04 1 2085 4192 8 49 3 1 921 15 516 51 847 40 51 1 2284 4242 7 50 5 1 966 15 887 53 790 40 99 1 2383 4293 8 51 7 2 013 16 273 55 779 41 49 1 2582 4346 2 53 0 2 061 16 672 57 816 41 99 1 2681 4399 8 54 3 2 111 17 086 59 902 42 51 1 2880 4454 8 55 7 2 163 17 516 62 039 43 04 1 2979 4511 2 57 1 2 217 17 962 64 228 43 59 1 3178 4569 0 58 6 2 273 18 426 66 473 44 15 1 3377 4628 4 60 1 2 331 18 908 68 774 44 72 1 3476 4689 3 61 7 2 392 19 409 71 135 45 31 1 3675 4751 8 63 4 2 454 19 930 73 558 45 91 1 3874 4816 0 65 1 2 520 20 472 76 044 46 53 1 40 80 73 4882 0 66 9 2 588 21 037 78 597 47 17 1 42 72 49498 68 7 2 659 21 626 81 220 47 82 1 44 71 5019 5 70 7 2 732 22 239 83 914 48 50 1 46 70 50912 72 7 2 809 22 879 86 684 49 19 1 48 69 5165 0 749 2 890 23 547 89 533 49 90 1 50 68 52410 77 1 2 974 24 245 92 464 50 64 1 52 67 53192 79 4 3 061 24 974 95 481 51 39 1 54 66 5399 8 81 8 3 153 25 737 98 587 52 17 1 57 65 54829 844 3 249 26 535 101 786 52 97 1 59 64 5568 5 87 0 3 349 27 371 105 084 53 80 1 62 63 5656 9 89 8 3 454 28 247 108 484 54 66 1 64 62 57482 92 7 3 564 29 166 111 992 55 54 1 67 61 5842 4 95 8 3 680 30 130 115 613 56 45 1 70 60 5939 8 99 0 3 802 31 143 119 353 57 39 1 73 59 6040 4 102 4 3 929 32 209 123 217 58 36 1 75 58 6144 6
26. 10 Number of rejection iterations grow 1 Rejection growing radius in pixels markrej yes Mark rejected points graphic stdgraph Graphics output device cursor Graphics cursor inputask YES mode ql Note that we ve set high_rej 0 and low_rej 2 in order to try to avoid having the continuum t being pulled down by absorption lines But these tting parameters should be played with according to the user s judgement Again though try to stick with the lowest order possible on continuum 218 Show and Tell of the Final Result You will now have in solar nal ec a respectable solar spectrum There are several ways to explore this nal result and make hard copies You can certainly use splot to plot order by order I like to use specplot which can display all orders at once Here is the parameter le Image Reduction and Analysis FacilityPACKAGE echelleTASK specplot spectra solar final ec List of spectra to plot apertur Apertures to plot bands 1 Bands of 3D images to plot autolay yes Use automatic layout algorithm autosca yes Scale to common mean for automatic layout fractio 0 Fraction of automatic minimum separation step units wavelength Coordinate units scale 1 Default intensity scale offset 0 Default intensity offset step 0 Default separation step ptype 1 Plotting type labels user Type of labels ulabels User labels file xlpos 1 02 X label position fraction of range ylpos 0
27. 105 9 4 064 33 329 127 212 59 37 1 78 57 6252 4 109 7 4 205 34 509 131 344 60 41 1 82 56 6364 0 113 6 4 354 35 753 135 622 61 49 1 85 55 6479 7 117 8 4 512 37 065 140 053 62 61 1 88 54 6599 7 122 2 4 678 38 451 144 646 63 77 1 92 Appendix F System ef ciency A plot of the overall system ef ciency is shown in Figure 9 This plot shows the results of several attempts at measuring system ef ciency on several different dates with different ux standard stars Since conditions were not always perfectly 59 HIRES Manual Instrument Description photometric some variation is expected The ordinate is the combined absolute ef ciency of telescope HIRES Tektronix CCD It does not include losses from the slit from an ADC from an image rotator or from atmospheric absorption Solid line curves represent measured ef ciencies based on actual measure ments of ux standards through wide open slit Dotted line curves are predicted ef ciencies based on the measured Ist order ef ciency and knowledge of the wavelength dependence of the optical system ef ciency Since these curves also include the ef ciencies of the three telescope mirrors they may be expected to decline as the telescope gets dirty By way of passing interest HIRES by itself peaks at about 13 ef ciency But there are three aluminum telescope mirrors out there in the telescope ahead of HIRES in the photon path Each telescope mirror primary secondary and tertiary when cleaned h
28. 627 mCD GRATING 250 gr mm ORDER 2 Order Blaze A FSR A DEL mm DEL asec HEIGHT mm LENGTH mm DISP A mm 119 2994 8 25 2 0 995 7 916 4 863 28 94 0 87118 3020 2 25 6 1 011 8 051 5 866 29 18 0 88117 3046 0 26 0 1 028 8 189 6 885 29 43 0 88116 3072 3 26 5 1 046 8 330 7 922 29 68 0 89115 3099 0 26 9 1 064 8 476 8 977 29 94 0 90114 3126 2 27 4 1 082 8 625 10 050 30 20 0 91113 3153 9 27 9 1 101 8 778 11 141 30 47 0 92112 3182 0 28 4 1 120 8 936 12 251 30 74 0 92111 3210 7 28 9 1 140 9 098 13 381 31 02 0 93110 3239 9 29 5 1 160 9 264 14 531 31 30 0 94109 3269 6 30 0 1 181 9 435 15 702 31 59 0 95108 3299 9 30 6 1 203 9 610 16 894 31 88 0 96107 3330 7 31 1 1 225 9 791 18 107 32 18 0 97106 3362 1 31 7 1 248 9 976 19 343 32 48 0 98105 3394 1 32 3 1 271 10 167 20 602 32 79 0 99104 3426 8 32 9 1 295 10 364 21 885 33 11 1 00103 3460 1 33 6 1 320 10 566 23 192 33 43 1 00102 58 HIRES Manual Instrument Description 3494 0 34 3 1 345 10 774 24 524 33 76 1 01101 3528 6 34 9 1 371 10 989 25 882 34 09 1 02100 3563 9 35 6 1 398 11 210 27 267 34 43 1 04 99 3599 9 36 4 1 426 11 437 28 679 34 78 1 0598 3636 6 37 1 1 455 11 672 30 119 35 14 1 0697 3674 1 37 9 1 484 11 914 31 588 35 50 1 0796 3712 3 38 7 1 514 12 163 33 087 35 87 1 0895 3751 4 39 5 1 546 12 421 34 616 36 25 1 0994 3791 3 40 3 1 578 12 687 36 178 36 63 1 1093 3832 1 41 2 1 611 12 961 37 773 37 02 1 1192 3873 8 42 1 1 646 13 244 39 401 37 43 1 1391 3916 3 43 0 1 681 13 537 41 064 37 84 1 1490 3959 8 44 0
29. 7 02 1 1192 3873 8 42 1 0 846 6 622 37 293 37 43 1 1391 3916 3 43 0 0 865 6 768 36 438 37 84 1 1490 3959 8 44 0 0 884 6 920 35 564 38 26 1 1589 4004 3 45 0 0 903 7 076 34 670 38 69 1 1688 4049 8 46 0 0 924 7 238 33 757 39 13 1 1887 4096 4 47 1 56 HIRES Manual Instrument Description 0 945 7 405 32 823 39 58 1 1986 4144 0 48 2 0 966 7 578 31 868 40 04 1 2085 4192 8 49 3 0 989 7 758 30 891 40 51 1 2284 4242 7 50 5 1 012 7 944 29 891 40 99 1 2383 4293 8 51 7 1 036 8 136 28 867 41 49 1 25 4346 2 53 0 1 061 8 336 41 99 1 26 27 819 81 43998 543 1 087 8 543 26 745 42 51 1 28 80 4454 8 55 7 1 114 8 758 25 648 43 04 1 29 79 4511 2 57 1 1 142 8 981 24517 43 59 1 31 78 4569 0 58 6 1 170 9 213 23 362 44 15 1 33 77 46284 601 1 200 9 454 22 477 44 72 1 34 76 4689 3 61 7 1 232 9 704 20 961 45 3 1 36 75 4751 8 63 4 1 264 9 965 19318 45 91 1 38 74 4816 0 651 1 298 10 236 18 433 46 53 1 40 73 4882 0 66 9 1 333 10 519 17 118 47 17 1 42 72 49498 68 7 1 370 10 813 15 767 47 82 1 44 7 5019 5 70 7 1 408 11 120 14 379 48 50 1 46 70 50912 72 7 1 447 11 440 12 952 49 19 1 48 69 5165 0 74 9 1 489 11 774 iasi 49 90 1 50 68 5241 0 77 1 1 532 12 122 9 974 50 64 1 52 67 53192 79 4 1 577 12 487 8 420 51 39 1 54 66 5399 8 81 8 1 624 12 869 6 820 52 17 1 57 65 5482 9 84 4 1 674 13 268 5 172 52 97 1 59 64 5568 5 87 0 1 725 13 686 3 473 53 80 1 62 63 5656 9 89 8 1 779 14 124 1 722 54 66 1 64 62 5748 2 92 7 1 836 14 583 0 085 55 54 1 67 61 5842 4 95
30. 8 1 895 15 065 1 950 56 45 1 70 60 5939 8 99 0 1 958 15 572 3 876 57 39 1 73 59 6040 4 102 4 2 023 16 104 5 866 58 36 1 75 58 6144 6 105 9 2 092 16 665 7 922 59 37 1 78 57 6252 4 109 7 2 164 17 254 10 050 60 41 1 82 57 HIRES Manual Instrument Description 56 6364 0 113 6 2 241 17 876 12 251 61 49 1 85 55 64797 117 8 2 321 18 533 14 531 62 61 1 88 54 65997 122 2 2 406 19 225 16 894 63 77 1 92 53 6724 3 126 9 2 496 19 958 19 343 64 97 1 95 52 68536 131 8 2 591 20 733 21 885 66 22 1 99 51 6987 9 137 0 2 691 21 555 24 524 67 52 2 03 50 71277 142 6 2 797 22 426 27 267 68 87 2 07 49 7273 2 148 4 2 910 23 351 30 119 70 27 2 11 48 74247 154 7 3 030 24 334 33 087 71 74 2 16 47 75827 161 3 3 157 25 381 36 178 73 26 2 20 46 7747 5 168 4 3 293 26 497 39 401 74 85 2 25 45 79197 176 0 3 437 27 689 42 764 76 52 2 30 44 80997 184 1 3 592 28 962 46 276 78 26 2 35 43 8288 0 192 7 3 757 30 326 49 948 80 08 2 41 42 84854 202 0 3 934 31 788 53 790 81 98 2 46 41 86923 212 0 4 124 33 358 57 816 83 98 2 52 40 8909 6 222 7 4 328 35 048 62 039 86 08 2 59 39 9138 1 2343 4 548 36 870 66 473 88 29 2 65 38 9378 6 246 8 4 786 38 837 71 135 90 61 2 72 37 9632 0 260 3 5 042 40 966 76 044 93 06 2 80 36 9899 6 275 0 5 320 43 275 81 220 95 65 2 88 FORMAT IN 2ND ORDER OF THE CROSS DISPERSER ECHELLE grooves mm 52 68 Blaze Angle 70 4 Theta 5 0 DIAMETERS Collimated Beam 0 3028 mTelescope 10 90 m Collimator Focal Length 4 1547 mCamera Focal Length 0 7
31. E CENTERING PARAMETERS width 40 Profile centering width radius 40 Profile centering radius thresho 10000 Detection threshold for profile centering AUTOMATIC FINDING AND ORDERING PARAMETERS nfind 30 Number of apertures to be found automatically minsep 50 Minimum separation between 1000 Maximum separation between spectra order increasing Order of apertures RECENTERING PARAMETERS apertur Select apertures npeaks INDEF Select brightest peaks 42 HIRES Manual Instrument Description 55 shift yes Use average shift instead of recentering RESIZING PARAMETERS limit INDEF Lower aperture limit relative to center ulimit NDEF Upper aperture limit relative to center ylevel 0 1 Fraction of peak or intensity for automatic widt peak yes Is ylevel a fraction of the peak bkg no Subtract background in automatic width r_grow 1 1 Grow limits by this factor avglimi yes Average limits over all apertures TRACING PARAMETERS t_nsum 8 Number of dispersion lines to sum t_step 16 Tracing step t_nlost 128 Number of consecutive times profile is lost befo t_funct spline3 Trace fitting function t_order 3 Trace fitting function order t_sampl Trace sample regions t naver 1 Trace average or median t niter 10 Trace rejection iterations t low 2 5 Trace lower rejection sigma t high 2 5 Trace upper rejection sigma t grow 0 Trace rejection grow
32. HIRES USER S MANUAL KECK TELESCOPE UCO LICK OBSERVATORY Steven S Vogt Santa Cruz California May 4 1994 HIRES Manual Introduction Contents iii Histor Tables M PE iv Chapter eon oo 1 Chapter 2 Instrument Description ga ee Fee eek FER ENS 2 Chapter Introd ct n ae qu ecu d eet i ee 1 Chapter 2 Instrument Descriptio aie epo eee nte diee edi se Ble 2 Section Summary of Characters CS scissors vans tasses rode ERES D RETOURS 2 section 2 Description of Light Path oo ends Neves 2 Section 3 Detailed Description of Principal Components 5 Entrance FECI S 5 Atmospheric Dispersion Compensator 5 Image o deii ind Pasce uto Me ose 5 TV 4 Camera 5 Calibration Lamp saves 6 Absorption Cell cs titan a uie e EUH CU REV gn 9 Decker Tray and asc s bo ted 9 DI ced Sande 11 Bebind The Shit Filter Wheels iee 11 Exposure Control Shutter 14
33. LAY variable is not set the program will prompt the user to enter one of the terminal types known to Lick Mongo The simulator then searches the current directory and the library directory looking for a setup le to be used to display the Echelle format A list of all the setups found in these directories is presented and the user is asked to choose which setup Only two options are presently of relevence to HIRES users the others are for other developmental experiments Pick either 2 for the rst order CD format or 3 for 2nd order CD format Once selected using the information contained in the setup le the simulator draws a picture of the Echelle format At this point it would be wise to position this relatively large graphic window such that it does not completely obscure the prompt line of your present window You may sometimes be asked to enter data from this window and unless it s prompt line is visible you may forget that this window exists In the large window showing the spectral format for each Echelle order within the speci ed wavelength limits one free spectral range FSR centered on the Echelle blaze is drawn Most of the light in any Echelle order is within one FSR of the Echelle blaze wavelength for that order There is some light in each order more than one FSR away from the blaze but the intensity drops rapidly On a display which supports color the simulator extends the length of each Echelle order by drawing ano
34. Tektronix plot window If the orders all look good you have successfully located and traced all the echelle orders and are done with apall Generate the Flat Field Image The next task is to generate a at eld image from the quartz which can remove pixel to pixel predominantly high spatial frequency variations We do this using the task apnormalize This task will take the quartz image remove the low spatial frequency variations i e blaze pro le and create a normalized at eld image which I will call at The reason we would like to normalize out the low frequency quartz spectrum variations is that doing a straight division by a quartz frame will give excess weight to those pixels where the quartz illumination happens to be low either away from 44 HIRES Manual Instrument Description blaze or away from the center of the aperture One could not go on to perform an optimal extraction if you at elded in this manner Here is the apnormalize parameter le for doing this using quartz imh as the input at imh as the output Image Reduction and Analysis FacilityPACKAGE echelleTASK apnormalize input quartz List of images to normalizeoutput flat List of output normalized images referen List of reference images interac yes Run task interactively find no Find apertures recente no Recenter apertures resize no Resize apertures edit no Edit apertures trace no Trace apertures fittrac y
35. The instrument simulator accepts these keywords and carries their values from input to output unchanged An observer may have a number of key spectral features which need display ing at their respective positions on the echelle format The Echelle Simulator will accept a le containing the wavelengths of spectral lines and display those lines with any desired velocity shift on its graphics The existence of such a le can be indicated using the WAVEFILE keyword in the Setup Con guration le and it can also be indicated interactively during the execution of the program Each line of the le contains a description of one spectral line The program looks for a wavelength expressed in Angstrom a boolean value T or F which describes whether the line is telluric and thus should not be redshifted and a statistical weight The statistical weight is used by the program during the design of new spectrographs It is intended to assist the program in choosing an Echelle groove spacing which places certain spectral lines near the blaze Section 2 Starting the format Simulator Starting the Echelle Simulator can be done by typing the command echelle or echelle amp if you want to run it in the background and keep the window available for other input If the user is running the X Window System and the user s environment de nes the DISPLAY variable the simulator will assume that the graphics should be displayed in an X Window If the DIS P
36. This detector is a Tektronix 2048EB2 CCD This CCD is optimized for the visible and shows a pronounced roll off in quantum efficiency in the ultraviolet The science grade Tek CCD for HIRES has not yet been nor may ever be received The CCD features 24 micron pixels in a 2048 by 2048 format It is a thinned backside illuminated chip with surface treatment and AR coating Figure 7 shows the quantum efficiency for this CCD as measured at UCO Lick at operating temperature Note that the QE drops very rapidly below 0 38 microns This is rather a shame since the CCD effectively dies before the 2nd order CD efficiency curve rises to a peak thus producing a dip in the overall instrument throughput in the 0 35 micron region All the rest of the HIRES optics transmit very efficiently all the way down to below 0 3 microns One very prominent distinguishing cosmetic defect of this CCD is a large felt tip pin mark near the center of the CCD It was kindly added by some technician at Tektronix to remind us that this virtually flawless 100 000 CCD is only an engineering grade device Unfortunately the folks at Tektronix seemed to have forgotten how to make science grade devices so we are stuck with this annoying blob It is marked in the HIRES format simulator as a red square though it is irregular in shape Take care to avoid this region when positioning critical spectral regions on the CCD 21 HIRES Manual Instrument Description Figure 7 Tektroni
37. accelerator keys Modifying the display The overall display can be modi ed by the use of single accelerator keystrokes or menu clicks Key Show OpticalHW nd the complete menu of optical Show All Setup Display the complete menu of instrumental setup Default Setup Restore the originally displayed menus Refresh All Redraw everything Zoom the display to show only the region where the detector is currently located 1 1 1 t th Display more information abou detector s 30 HIRES Manual Instrument Description Quit the graphical interaction and begin Exit2CmdLinMod command line interaction see Section 4 below Display Wavelen Un Display the wavelengths of every fth order Un Display the order numbers of eve Display Orders or ER y Un Plot a temporary outline of the detector s at the current location of the Mark Detector detector These outlines will be visible in a hardcopy Identify the spectral line nearest to the X ra 1 Cursor IM the detector s over the Echelle format the readout window of det Modifying the Setup 31 HIRES Manual Instrument Description Modifying the Optics The Echelle Simulator can be used during intial design studies of new Echelle spectrographs It is possible to modify the properties of many of the optical elements while the program is running Under normal circum
38. am by either of two red blue optimized collimator mirrors The collimated beam is then sent to an echelle grating 1 x 3 mosaic and then to cross disperser grating 2 x mosaic It makes a 40 turn off the cross disperser and into a large 30 diameter entrance aperture prime focus camera The camera features two large corrector lenses with very special sol gel anti reflection coatings a large light weighted Hextek primary mirror and a thick fused silica field flattener which also serves as the dewar vacuum window Inside the dewar at the camera s prime focus is a Tektronix 2048 2 1 CCD A slowly actuated 15 also provided at the field flattener dewar window to keep this sol gel coated optic clean and to keep the CCD reasonably dark if lights must be turned on inside the spectrometer room The LN2 dewar near the CCD is filled automatically about once per day from a large LN2 storage dewar sitting outside the HIRES room The storage dewar needs manual re filling about once per week by qualified CARA technical personnel Section 3 Detailed Description of Principal Components Entrance Hatch The entrance hatch is a simple hinged door It is normally kept closed when not using the instrument for any extended period It serves to isolate the slit area from dome light such that calibrations can be made during the day or while someone else is using the telescope It also serves the important function of kee
39. ane at UCO Lick is championing this Hopefully it will soon be available as a UCO Lick Technical Report You may also wish to run a session of the HIRES echelle simulator to aid in nding features If you get it set up fairly closely to how the data was obtained you can read wavelengths off at any column in any order quite rapidly Wavelength tting is a bit tricky since if you get a few wrong identi cations near the start you can end up going down an incorrect path and arrive at an incorrect solution This is largely because there are so many Th Ar lines that the routine can almost always nd one near where it thinks one should be And then if you let it start nding its own lines without properly constraining it enough it will quickly accumulate a list of incorrectly identi ed lines which will overwhelm your relatively small list of proper identi cations and converge on the wrong solution 48 HIRES Manual Instrument Description So you have to start out slowly giving it a few tens of lines scattered across the format and letting it nd small numbers of its own When con dent that it is nding lines correctly then you can turn up maxfeat to the maximum of 3000 and really let it go hog wild But to begin with suggest setting maxfeat at about 20 and inputting 10 to 20 features manually Of course the easiest landmarks to identify are the very bright Argon lines which appear redward of about 7000 A but if you don t have any of th
40. ar 19 00 What type of magnitude Johnsonz1 2 1 Lunar phase days 0 Sky brightness at 5500A is 21 9 magnitudes arcseconds 2Enter airmass 1 300 Enter exposure time seconds 3600 Star counts 284 16 9Sky counts 73 8 6Dark counts 26 5 1 Readout 2 2Net star 284 20 3 54 HIRES Manual Instrument Description Net S N 14 per 41 mA pixel 26 per 142 mA resolution element The entries within the square brackets are the default parameters which will be used if you just hit lt return gt on each line If you enter new values the defaults will be updated to your latest values In the summary table of counts at the bottom the middle column represents signal level from each source and the right column lists the relative contribution of each source to the total noise One normally exits the S N estimator with a If you wish to generate a of the results you create when running the S N estimator before you run the program type script lename where lename is the name of where your S N estimator will be saved Then remember to exit from that script after terminating the S N estimator program with a cntrld Chapter 8 References Epps H W and Vogt S S 1993 Applied Optics 32 6270 Leach R 1988 Publ Astronomical Society of the Paci c 100 1287 Marcy G W and Butler R P 1992 P A S P 104 270 Massey P 1992 A User s Guide to CCD Reductions with IRAF National Optical
41. are used in conjunction with the slit while all other decker apertures define both slit length and width and are used in place of the slit jaws When using the latter the slit jaws must be fully opened to get them out of the way HIRES Manual Instrument Description Figure 1 HIRES Schematic collimators echelle mosaic shutter cell FW1 FW2 field cross disperser mosaic corrector lenses camera mirror An Iodine absorption cell can be moved into position directly in front of the slit for very precise wavelength calibration Quartz halogen incandescent lamps and hollow cathode lamps located up near the ceiling of the slit area provide for flat fielding and wavelength calibration Light from these calibration lamps gets fed into the HIRES optical axis by reflection off a feed mirror which slides into place when calibration is desired The calibration lamp system has a filter wheel for chromatic and intensity control and one position of that filterwheel contains a Fabry Perot etalon for producing Edser Butler fringes along the echelle orders to aid in wavelength calibration Immediately behind the slit are two filter wheels mainly for filters required for blocking unwanted cross disperser orders Behind the filterwheels is a shutter for controlling the start and stop of an exposure HIRES Manual Instrument Description The f 13 7 beam then expands and gets collimated to a 12 diameter be
42. as only about 85 ef ciency So 1 0 853 or almost 40 of the light is lost to the telescope and thus never makes it to the HIRES entrance slit HIRES is attached to effectively a 7 7 meter telescope Clearly there are gains to be had with using silver on some or all of the telescope mirrors but at the price of losing the region below about 3400A Keck II will apparently have all silver mirrors It is my hope that we may be able to borrow the silver tertiary for HIRES on Keck I occasionally Also worth noting is that all of the HIRES lenses and mirrors transmit ex tremely well down to the atmospheric cut off The rapid fall off in system ef ciency towards the ultraviolet is due partly to the roll off of the cross disperser s blaze function in 1st order and also to the roll off in of the rst light engineering grade Tektronix CCD A uv blazed rst order CD is under construc tion to improve this This plot is simply meant to be a rough guide as to which order to choose of the cross disperser and what the approximate throughput will be Ef ciencies are for the center of the echelle free spectral range at any order For more accurate ef ciency estimates one must include also the slit losses for given seeing and atmospheric absorption as well as the effects of sky background dark current readout noise and binning on the nal signal to noise of the data This is easily done using the HIRES S N estimator program described in a previous s
43. at to be positioned as desired left right on the CCD and looks to the user as though one is moving the CCD left right around a fixed echelle format The echelle mosaic is housed in a dust tight enclosure Since these gratings can never be cleaned one should never attempt to touch them or even to get near them And their cover should be kept closed when not in use Cross Disperser CD The cross disperser hereafter CD is a mosaic of 2 12 by 16 gratings mosaiced such that the effective length of any ruling 15 24 and the total ruled width is 16 The mosaic concept is quite similar to that of the echelle The cross disperser ruling is 250 grooves mm The collimator to camera angle is 40 The intended blaze angle of this CD was supposed to have been 5 343 but came out 4 3 The effect of this error was to put the first order blaze peak near 0 56 microns rather than the intended 0 7 microns and the 2nd order blaze peak at 0 28 microns rather than the intended 0 35 microns This CD is intended to be used in Ist order in the visible and in 2nd order in the ultraviolet blue Note that the orders get uncomfortably close together down in the uv with the CD in Ist order but the spacing doubles n 2nd order Appropriate order blocking filters will have to be used to eliminate unwanted CD orders In 2nd order one will generally be limited to a wavelength span per observation of 3 2 times the bluest wavelength observed becau
44. ators A cross disperser which gives much more order separation in the visible would also probably be used in this mode and could provide enough interorder space for perhaps 100 objects while still achieving good wavelength coverage Also a mirror could be installed in place of the cross disperser for multi object or longslit single order work Infrared arrays HgCdTe are also now becoming available which provide excellent sensitivity and low noise imaging capability out to at least 2 6 microns The HIRES optical train is designed to be quite ef cient and to produce quite good images out to these wavelengths and such an IR array could be easily installed in the camera in place of the conventional CCD s A different cross disperser would also be purchased for use with this detector HIRES is nominally designed to be used up to resolutions of about 100 000 without image slicers However in conditions of bad seeing or for much higher resolution work image slicers can be added to maintain high throughput at the slit The collimators are oversized to accept the square beam from a Richardsor style slicer and the camera s image quality will be good enough to provide resolutions of at least 200 000 CCD s with 7 5 micron pixels will also be required for such resolutions and appear to be now available in 40962 formats One could also envisage a double pass very high resolution mode with the cross disperser rotated to send the light back to the echelle but
45. ble to where your object orders will be To nd and trace the echelle orders we will use the task apall Here is its parameter list IRAFImage Reduction and Analysis FacilityPACKAGE echelleTASK input quartz List of input images output List of output spectra format echelle Extracted spectra format referen List of aperture reference images profile List of aperture profile images interac yes Run task interactively find yes Find apertures recente yes Recenter apertures resize no Resize apertures edit yes Edit apertures trace yes Trace apertures fittrac yes Fit the traced points interactively extract yes Extract spectra extras yes Extract sky sigma etc review yes Review extractions line 900 Dispersion line nsum 10 Number of dispersion lines to sum DEFAULT APERTURE PARAMETERS dispaxi 1 Dispersion axis 1 along lines 2 along columns lower 20 Lower aperture limit relative to center upper 20 Upper aperture limit relative to center apidtab Aperture ID table optional DEFAULT BACKGROUND PARAMETERS b_funct chebyshev Background function b_order 1 Background function order b_sampl 28 21 21 28 Background sample regions b naver 3 Background average median b niter 0 Background rejection iterations b low r 3 Background lower rejection sigma b high 3 Background upper rejection sigma b grow 0 Background rejection growing radius APERTUR
46. ccelerator keys are single keystrokes An accelerator which is associated with a Boolean parameter will toggle that parameter from one state to the other An accelerator which is associated with a string or numeric parameter will prompt the user for a new value If the display is an X11 server the prompt will change the cursor into a question mark and the prompt will be visible at the bottom of the screen On other displays the prompt will appear on the text screen if one exists or on the graphics screen Again this is where you will want to be sure your text screen is not buried under the graphic screen Mouse drag can only be used on X11 displays Dragging can be done with xed size objects or with rubber objects The Instrument Simulator allows the readout window if windowed down to some subset of the full CCD format to be indicated by dragging a rubber rectangle over the display The position of the detector s can be modi ed by dragging a xed size rectangle of the same size as the detector When dragging a xed size rectangle it may be grabbed at any of 9 locations de ned by the corners and points halfway between Menu click can be used for items which are displayed in the lists of text at the side of the display It requires that the display have some kind of moveable cursor The cursor is moved over the menu item and any unassigned key or mouse button is hit The user will then be prompted for a change in the same manner as for
47. ccurate measurement of instrumental profiles and flat fielding Light from the calibration lamps is first collected and collimated by a cemented doublet HTF1 Fused Silica lens located just above the filter wheel The collimated beam then Silica NaCl Fused Silica lens and then off a retractable folding pupil and adds a central obstruction The beam then passes through a 12 position filter wheel to a cemented triplet Fused flat which directs the beam into the spectrometer The triplet lens produces a beam of proper numerical aperture f 13 7 focused at the slit plane and a virtual pupil of the correct size a 45 arcsecs HIRES Manual Instrument Description and distance 58 diameter 785 ahead of the slit to accurately mimic the telescope s exit pupil The HTF1 element a glass very similar in dispersive properties and transmission to CaF but without hygroscopic problems and NaCl element were required in order to control pupil distortion and pupil walk over the very wide chromatic range 0 3 to 2 microns of the spectrometer The NaCl element was encapsulated between the fused silica elements to avoid hygroscopic problems The optical system provides a 2 1 magnification so the typically 3 5 mm diameter spot of light produced by hollow cathode lamps is only 6 10 mm or 8 14 arcsec at the slit far too small for longslit wavelength calibration For longslit work the lamp is simply scanned along the slit direction A li
48. ce with FITS les the keywords are up to 8 characters long Many of these keywords are identical to the keywords which will be used by the Keck Data Acquisition System when it is documenting actual observation Each keyword is followed immediately by in columns 9 10 The values may be found anywhere after the starting in column 11 The principal difference between the Echelle Simulator con guration les and true FITS headers is the existence of carriage control Echelle Simulator con guration les contain carriage control and are intended to be edited by any text editor Each time the Echelle Simulator is run it outputs hidden versions of the three con guration les These are named ech spc ech det and ech set These can be compared with the original inputs and any changes made by user interaction to verify that the program is working as desired Upon request of the user the program also writes out an observation setup le in either of 2 formats The rst format is identical to the inputs described below The second format contains FIORD commands designed to command the Keck HIRES spectrograph to the 26 HIRES Manual Instrument Description given con guration The user can also edit these les as desired without going back and rerunning the simulator using your favorite text editor There are several keywords which are de ned by the Keck HIRES data acquisition system which are not used by the instrument simulator
49. des on the UCO Lick network computer system as home umbra mk bin sparc sn Keck observatory should also have a version for public release Contact aconrad keck hawaii edu for assistance Be sure you get up to date version there are some older versions oating around with incor rect ef ciency numbers Then just answer the questions as prompted If in doubt about an input value the default will often suf ce The program also remembers all previously used values and reuses these as new defaults to speed up repetitive inquiries Ef ciencies used for the S N calculations are our best estimate from actual rst light performance at the telescope during commissioning Here is a sample of the prompts you will receive when computing the S N for a given set up of HIRES Wavelength of interest A 5500 Blaze center A 5517 Free spectral range A 86 20 Enter cross disperser order 1 Spectrograph efficiency at 5517A blaze peak is 18 4 Blaze function is 87 9 Single order efficiency at 5500A is 16 1 Extinction at 5500A is 0 12 magnitudes airmass Enter slit height arcseconds 13 13 Enter slit width arcseconds 1 000 Enter seeing FWHM arcseconds 0 8000 Slit throughput is 74 1 Slit width projects to 3 5 pixelsStar rows 13Sky rows 56 Enter dark count electrons unbinned pixel hour 2 000 Enter readout noise electrons pixel 4 300 Enter binning factor dispersion 1 Enter binning factor cross dispersion 4 Enter magnitude of st
50. e closest reference spetrum in time There are keywords and options for doing many such operations The point is that refspec is much more powerful than illustrated here Applying Dispersion Correction to Object Spectrum We would now like to use the task dispcor to linearize the dispersion of our program object spectrum solar ds ec imh Epar into the parameter list now for dispcor Image Reduction and Analysis FacilityPACKAGE echelleTASK dispcor input solar ds ec List of input spectraoutput List of output spectra lineari yes Linearize interpolate spectra databas database Dispersion solution database table Wavelength table for apertures wl INDEF Starting wavelength w2 INDEF Ending wavelength dw INDEF Wavelength interval per pixel nw INDEF Number of output pixels log no Logarithmic wavelength scale flux yes Conserve flux samedis no Same dispersion in all apertures global no Apply global defaults ignorea Ignore apertures confirm no Confirm dispersion coordinates listonl no List the dispersion coordinates only verbose Print linear dispersion assignments logfile Log file mode ql There are many options here but we want just a simple ux conserving linear interpolation After running this task you should do a quick sanity check and use splot to browse around the spectrum checking against known reference spectra easy to 204 for the Sun to see that obvious fetures like H
51. ection Our best estimate of actual system ef ciency has been incorporated into this simulator Feedback from observers though on their measured ef ciencies are always welcome not only to aid in converging on true ef ciency numbers but also to check for and guard against system ef ciency decline with time Figure 9 Spectrometer Telescope Ef ciency 60 HIRES Manual Instrument Description 7 25 93 HR 5401 10 8 93 HR 9087 1st orde 4 T 7 18 83 HR 8634 System Efficiency 96 order 02 03 04 05 06 07 08 09 1 0 Wavelength microns Appendix G Special considerations for low S N and or long integration observations This section not yet completed Appendix H Future HIRES upgrades The instrument described thus far is simply the core version of the nal in strument There were not enough funds available to build the entire instrument by rst light In the future as further funding becomes available and providing science needs dictate I expect to add a number of useful features For instance one can add new cross dispersers to best match the order separation wavelength coverage required of any given project It may prove worthwhile in the future to consider adding other echelles particularly if detector formats evolve consider ably For example an R 1 5 echelle optimized for wide wavelength coverage in the ultraviolet in conjunction with a rst order uv cross disper
52. eduction and Analysis FacilityPACKAGE echelleTASK refspectra input solar ds ec List of input spectra referen thar ec List of reference spectra apertur Input aperture selection list refaps Reference aperture selection list ignorea no Ignore input and reference apertures select match Selection method for reference spectra sort Sort key group Group key time no Is sort key a time timewra 17 Time wrap point for time sorting overrid no Override previous assignments confirm yes Confirm reference spectrum assignments assign yes Assign the reference spectra to the input spectr logfile STDOUT logfile List of logfiles verbose no Verbose log output answer yes Accept assignment mode ql This now takes the solution computed for thar ec imh and attaches it to solar ds ec imh At this point though you only know the true wavelength for each 51 HIRES Manual Instrument Description pixel in each order You will generally want to linearize or logarithmize or whatever the dispersion to some convenient sampling scale with the task of the next section Attaching wavelength references is generally far more complex than simply attaching a single solution to a single frame Often one will have pre and post Th Ar spectra and will want to interpolate between these Or one may wish to attach a solution from a group of reference spectra and to perhaps a group of program objects Or one may wish to attach th
53. ent Light from the telescope enters from the left in this schematic coming to focus at the f 15 nasmyth focus An entrance hatch at the front of HIRES seals off the slit area such that the instrument can be run during the day under high light level conditions in the dome The hatch also protects the slit area from dirt contamination and should be left closed when the instrument is not in use for any prolonged period The f 15 it s f 13 7 actually out to the farthest corners of the hexagonal primary beam then proceeds to focus at the HIRES slit plane The HIRES slit is actually 1 83 behind the nominal telescope nasmyth focal plane but well within the focus range and good imagery range of the telescope The slit plane is tilted such that light can be reflected up at an angle and re imaged onto a CCD TV acquisition and guiding camera This camera is a simple xed CCDTV staring at a 45 arcsec by 60 arcsec field centered on the entrance aperture of the spectrometer The TV camera has both color and neutral density filters for brightness and chromatic control on the guide target and also has variable focus and aperture control At nasmyth focal plane a brparting precision slit is provided for adjusting spectral resolution A series of decker plates just above and in very close proximity to the slit jaws is provided for de ning the entrance slit length Some of these decker apertures decker plate A slots are for defining slit length only and
54. erscan strip presently image columns 2070 to 2112 The baseline will be measured in the overscan area for each row and then a smoothed version of this baseline measure will be subtracted row by row from the image Trim yes will trim each image stripping off the rst 22 prescan columns which do not contain real image pixels and the columns beyond 2070 which at present are reserved for 40 HIRES Manual Instrument Description overscan pixels Zerocor yes will cause the image with IMAGETYP zero in its FITS header i e our named zero imh to be subtracted from each image to remove the bias level curently set near 1100 dn Darkcor yes will instruct the routine to use the image with the IMAGETYP dark keyword in the FITS header i e our le called dark imk to determine the dark current dn pixelsec and then scale that dark current to the correct exposure time for each image before then subtracting that dark current The other processing switches won t be used right now Most are fairly self explanatory Readaxi line tells the routine that the readout axis is along the row line direction We don t have a x le image yet for descibing and xing bad lines or columns The biassec and trimsec parameters shown here are correct for de ning the overscan and trim regions for the present single ampli er readout con guration They will be different for duakampli er readout and they may change also as we do more optimizing of the CCD
55. es Fit traced points interactively normali yes Normalize spectra fitspec yes Fit normalization spectra interactively line INDEF Dispersion line nsum 10 Number of dispersion lines 10 sum cennorm no Normalize to the aperture center thresho 10 Threshold for normalization spectra backgro none Background to subtract weights none Extraction weights nonelvariance pfit fitld Profile fitting type fitldlfit2d clean no Detect and replace bad pixels skybox 1 Box car smoothing length for sky saturat INDEF Saturation level readnoi 4 Read out noise sigma photons gain 2 38 Photon gain photons data number lsigma 4 Lower rejection threshold usigma 4 Upper rejection threshold functio spline3 Fitting function for normalization spectra order 3 Fitting function order sample Sample regions naverag 1 Average or median niterat 3 Number of rejection iterations low_rej 3 Lower rejection sigma high_re 3 High upper rejection sigma grow 0 Rejection growing radius mode If you do it interactively as you should the rst time through you will have the opportunity to play with all the tting parameters Try to use the lowest order spline as possible when tting out the quartz s low frequency variations or you will risk introducing ripples into your at elded spectrum Again be careful how you answer questions about resizing and editing apertures etc If you want to stick with the apert
56. ese in your spectrum stick with the strongest features at rst Here is a reasonable starting parameter list for ecid Image Reduction and Analysis FacilityPACKAGE echelleTASK ecidentify images thar ec Images containing features to be identified databas database Database in which to record feature data coordli linelists thorium dat User coordinate list match 1 Coordinate list matching limit in user units maxfeat 20 Maximum number of features for automatic identif zwidth 10 Zoom graph width in user units ftype emission Feature type fwidth 4 Feature width in pixels cradius 5 Centering radius in pixels thresho 10 Feature threshold for centering minsep 2 Minimum pixel separation functio chebyshev Coordinate function xorder 4 Order of coordinate function along dispersion yorder 4 Order of coordinate function across dispersion niterat2 5 Rejection iterations lowreje 3 Lower rejection sigma highrej2 3 Upper rejection sigma autowri no Automatically write to database graphic stdgraph Graphics output device cursor Graphics cursor input mode ql Another much easier way to wavelength calibrate is to use the solution from a previous calibration run and use ecreidentify to match to the previous solution making slight shifts etc This works quite well if the reference spectrum is near to the one you are working on I have not yet tried to see how far one can reach out to reference spectra which are sign
57. for as many features as you wish A lt gt will give you the position of the feature nearest the cursor When done marking lines in any order or at any time you may switch to other orders using the lt j gt and lt k gt keys to move backwards or forward among your orders Many other helpful options can be displayed as usual using lt gt in the plot mode I try to mark a few lines in the rst several orders a few near the center and a few near the last few orders before btting the routine go to try nding its own lines When nished marking a reasonable sampling of identi ed lines across the orders you are ready for some initial tting Type lt f gt in the plot window this stands t dispersion One uses a combination of maxfeat and threshhold to control the number of peaks found It will only nd peaks above the speci ed threshhold and will nd up to maxfeat of these We have the maxfeat parameter set at only 100 right now so it will nd a maximum of only 100 peaks above threshhold but that s ok for a rst timid try Make sure they are reasonably well distributed across the full eld of apertures you don t want it to nd all of them near the beginning etc You will now be presented with a plot of tting residuals w pixel Use the cursor and the d key to delete bad points and the lt f gt to re t the affect all features switch is already turned on If you ve done things right most of your residuals should be d
58. g at order widths and decide upon the correct value for width by measuring the width of the widest order Actually all orders should be very nearly all the same width save for slight anamorphic and distortion effects 43 HIRES Manual Instrument Description Here are some other noteworthy parameters The parameter line is the column where the order tracing routine starts its search set it at 900 to avoid starting in the dark blob near chip center which may confuse the algorithm This blob is a mark from a felt tip pen kindly put on this 100 000 CCD by some technician at Tektronix to remind us that this is an engineering grade device The parameters lower and upper de ne the lower and upper limits of the tracing aperture relative to order center The parameter b sampl de nes the background sample region and has been set to run just outboard of the tracing window here The parameter n nd must be at least as big as the number of orders to be found The parameter minsep must be set correctly but the parameter maxsep can be any number much larger than your order separation So when ready type g to exit and execute apall and start answering interactive mode prompts It will ask questions about whether or not you want to resize apertures for quartz edit apertures for quartz etc Your answers will depend on whether this is your rst time through or whether you have already run the routine and have previous aperture informat
59. h allows the user to write the data in FIGARO style format and thus bypass the FITS to FIGARO conversion if so desired At this time due partly to lack of a well supported and fully developed FIGARO system and partly to lack of in nite software manpower resources a FIGARO HIRES reduction suite of routines is not available from the HIRES development team No doubt existing FIGARO echelle packages will work with enough patience and tuning Section 2 IDL KHOROS and Others 36 HIRES Manual Instrument Description Since the HIRES data is in FITS format many other data reduction analysis packages can be used Gibor Basri and co workers at U C Berkeley prefer IDL and have many useful scripts and routines written to do echelle data reduction Others like the Khoros package All should work just ne though each will have its own particular bugs and irregularities to overcome before becoming user friendly for a task as complex as echelle data reduction Section 3 IRAF IRAF is the reduction environment recommended by the for HIRES An optimized version of IRAF utilities which have been set up to know about many of the actual instrument parameters lives on the CARA network and will be maintained by the project s software of ce First time users of IRAF and or echelle spectrometers would be very well advised to obtain a copy of A User s Guide to CCD Reductions with IRAF Massey 1992 This is an excellent guide to basic IRAF data red
60. holes begin occurring redward of about 5100 A Avoiding these holes and ensuring that the desired spectral range falls properly on the CCD requires accurate positioning of the echelle format on the CCD For extragalactic objects redial velocity must also often be taken into account To aid the observer in optimal positioning of the CCD on the echelle format a simulator was developed by Steve Allen at UCO Lick The underlying mathemat ics are described in the textbook by the original author of the code D J Schroeder Astronomical Optics Academic Press 1987 These algorithms provide a complete description of the Echelle format within the constraints of the 2 dimensional grating equations They do not handle the more general problem of modelling the 3 dimensional grating equations Other important algorithms used in the code are based upon the text by E Hecht amp A Zajac Optics Addison Wesley 1974 The code is able to model a spectrograph where an Echelle grating is fed by a collimated beam The beam leaving the Echelle grating may be cross dispersed by at most 1 cross dispersing grating and or up to 9 cross dispersing prisms This simulator also serves as a convenient means by which set up les for most all of the HIRES parameters can be created off line i e before going to the mountain while preparing for a run etc These set up les can then be uploaded to Mauna Kea and stored in the instrument computer prior to starting the obse
61. i cantly offset Eventually we hope to build a library of Th Ar reference spectra which can be used at any place around the HIRES format and thus always allow wavelength calibration to be done by ecreidentify If you had a reference spectrum called thar ref ec this is what your parameter list for ecreidentify would look like Image Reduction and Analysis FacilityPACKAGE echelleTASK ecreidentify images thar ec Spectra to be reidentifiedreferenc thar ref ec Reference spectrum shift 0 Shift to add to reference features cradius 5 Centering radius thresho 10 Feature threshold for centering refit yes Refit coordinate function databas database Database logfile STDOUT logfile List of log files mode ql Anyway here we go now in ecid The rst thing which will be displayed is a plot of the Ist aperture Move the cursor to a line you think you recognize and type lt m gt to mark If it beeps without marking try shifting the cursor a tiny bit to the right often you have to position the cursor slightly right of line center to get it to mark that line It will then respond with the column number and await an input wavelength If you change your mind and do not want to mark that line just hit return and then without moving the cursor hit lt d gt for delete then lt r gt for redraw the plot Using 49 HIRES Manual Instrument Description the lt m gt and lt d gt keys you can mark or delete and enter wavelengths
62. igure 3 Blue Blocking Filters 2 acri ie cie tores fece 15 Figure 6 Cross disperser efficiency 19 Figure 7 Tektronix CCD Quantum Effieiency cece eee cece 22 Figure 8 Typical appearance of the Simulator during interactive use 29 HIRES Manual Introduction List of Tables Fable 1 T V Filters e estt ee Ert tte 6 Table 2 Emp Pipers uu eed uide uiid abe 8 Table 3J HIRES De6Kets tvs et Ei eroe vecti n tote ri n des ada 10 Table 4 HIRES PIlterSEs a SN ne 12 Table 5 Some useful lter 13 iv HIRES Manual Instrument Description Chapter 1 Introduction HIRES was conceived in early 1987 in response to a call for instrument proposals for rst light of the Keck Ten Meter Telescope It went through three rounds of proposals before being selected as one of the initial complement of Keck rst light instruments It took about 5 years to build at a total cost of about 4 0 million It was designed and built in the technical laboratories of the UCO Lick Observatory at the University of California at Santa Cruz The name HIRES stands for High Resolution Echelle Spectrometer HIRES was designed to take advantage of the Keck telescope s large collecting area to push high resolution optical spectroscopy out to about V 20
63. ing at every 100 columns across the CCD You can go across the CCD once tting every 100 columns and you can return to places later for re tting if necessary until you ve got it just the way you want There is presently a diffuse halo in the scattered light like the ring nebula at very low light level centered roughly on the center of the CCD You may notice the double peaked signature of this halo as your cuts move across the chip It may require even 5 7 orders to t well But out near the edges away from this halo a lower order spline should suf ce Hopefully anti re ection coating the eld attener lens will reduce this halo Once you ve got a full set of columns t quit out of the routine It will then go away for a long time many mnutes calculating the proper smoothed t to the background in the row direction When t returns it will display a row cut across the image at row 1024 and you must repeat the above process for a series of rows across the image Again it is good to do a t every 100 rows across the CCD keeping the order as low as possible When nished quit out of the routine You should then use display and or implot to examine your de scattered light result to see that all looks as expected Extracting Orders and Compressing to 1 4 Spectra You are now ready to use apsum to extract the orders and compress them into l d spectra We will extract both solar ds imh and thar imh for this demo I didn t bother correcting
64. ing radius EXTRACTION PARAMETERS backgro none Background to subtract skybox 1 Box car smoothing length for sky weights none Extraction weights nonelvariance pfit fitld Profile fitting type fitldlfi2d clean no Detect and replace bad pixels saturat INDEF Saturation level readnoi 4 Read out noise sigma photons gain 2 38 Photon gain photons data number Isigma 4 Lower rejection threshold usigma 4 Upper rejection threshold nsubaps 1 Number of subapertures per aperture mode ql Obviously there are a large number of parameters in this very generalized and powerful task The ones shown here worked well for a shot in Ist order of the cross disperser in the 4800 to 7000 angstrom range where the decker used projects to a height of about 38 rows You will probably have to modify several parameters if your order spacing and or order widths set by the decker length usually are different Some of the most crucial parameters to set properly are width and radius I m told that the width parameter must be just slightly bigger than the width in rows or lines of the widest echelle order In our example this is about 38 rows so I set width to 40 Also the radius parameter should be set to the same value Eventually we will be able to use the instrument keywords and or set up routines to set this parameter automatically but for now you must display your image in SAOIMAGE using the task display roam around lookin
65. ing the bad lines and columns biassec 2100 2112 Overscan strip image section trimsec 23 2070 Trim data section zero Zero level calibration image dark Dark count calibration image flat Flat field images illum Illumination correction images fringe Fringe correction images minrepl 1 Minimum flat field value scantyp shortscan Scan type shortscanllongscan nscan 1 Number of short scan lines interac yes Fit overscan interactively functio spline3 Fitting function order 3 Number of polynomial terms or spline pieces sample Sample points to fit naverag 4 Number of sample points to combine 52 niterat 5 Number of rejection iterations low_rej 5 Low sigma rejection factor high_re 1 75 High sigma rejection factor grow 3 Rejection growing radius mode ql Input the names of the images you wish to correct i e reduce or the name of a which contains a list of the images to be corrected For our example these will be solar imh quartz imh thar imh dark imh and zero imh Type them all in on one line with commas but no spaces between The ccdtype parameter being set to object tells the routine to perform dark current correction only to les with IMAGETYP object in their FITS headers The max_cac parameter can be increased as allowed by available memory to speed processing time Oversca yes means we will be correcting each image for row to row baseline variations using the ov
66. ion les to give it the information necessary to compute a simulated HIRES spectrometer and its particular detector The complete description of an Echelle spectrograph requires copious amounts of information Most of this information does not change and it is convenient to store it in con guration les The simulator searches for con guration les in several directories The rst directory searched is the current working directory Next if the environment de nes EFDIR that directory is searched otherwise the program looks in the built in default directory 1 The simulator accepts 3 kinds of con guration les The rst 2 kinds of les rarely need changing they describe the telescope spectrograph optics spc and the detector at the focal plane det These les will be maintained and updated by Keck Observatory folks and will be write protected from general users The third kind of le contains the settings of all the moveable parts of the spectrograph which are expected to change from one observation to the next set It is this type of le that the observer will be creating modifying and storing for later use with HIRES On the UCO Lick systems this is home hires sla echelle lib The con guration les for the Echelle Simulator look like FITS les More detailed descriptions of these con guration les can be found in Steve Allen s UCO Lick Technical Report No 68 Con guration parameters are stored as keyword value pairs In accordan
67. ion stored away in the database subdirectory so answer carefully When satis ed with each t to each order type q to quit and move on to the next order As with all interactive question and answer sessions within IRAF If you get tired of answering yes s just type YES all caps If all the parameters are set reasonably well apall should have no problem nding all orders If it does have problems and you should check by going through in interactive mode at least once then try playing around with parameters And you can always do an end run around the auto order nding routines and just mark them by eye interactively if you wish It is very important at this stage to verify that your apertures are reasonably well t to the orders so I suggest looking at them in detail in the interactive mode of apall Be sure that apertures from adjacent orders do not ever overlap and that all orders except perhaps for the rst and or last which are often partial since they fall off the chip edges are present and accounted for When nished you will be asked if you want to write the apertures to the database You should answer yes and IRAF will create a subdirectory called database where it saves all the aperture information along with lots of other information to come Now you can extract and review each quartz order to check that they all look reasonable If you wish some hard copies just type snap and you ll get a laser print of the
68. kers alone will be preferable For work requiring a longer slit or narrower slit than 0 6 arcsecs requires use of the normal slit jaws In any case once either the slit or the decker is selected the collimator will automatically be refocussed properly Basically the system looks to see if decker plate A is being used If so it assumes you are to be using the slit jaws If not it wil refocus for the decker plates There is about a 1 8 difference in the focal planes of these two entrance apertures Section 5 CCD Readout Mode windowing binning fast slow readout modes MPP full well vs dark current modes Multiple vs single ampli er modes Section 6 Focussing Section 7 Taking Calibration Exposures Flat elds Wavelength calibration and instrumental pro le Th Ar hollow cathode lamps Observing at Keck HIRES Manual E B bands Iodine Absorption Cell Spectrum Dark Frame s Bias zero Frame s Day Twilight Sky and or Moon Spectra Section 8 End of the Evening Final calibration frames ShutdownDewar auto ll Section 9 End of the Observing Run Section 10 Observing Checklist Section 11 Observing Log Sheets Chapter 6 Data Reduction Section 1 FIGARO FIGARO is the CARA standard for quick look data reduction at Keck Obser vatory The HIRES data frames are normally written to disk in FITS format and FIGARO can read these FITS format les The FITS format is the default standard for HIRES However there is a switch selectable option whic
69. l information in a subdirectory called pixels and you can cd there and ls them to see that they really do now exist The point here is that IRAF image les are actually associated pairs of header and pixel les Thus when copying deleting etc such les it is generally much easier to use the commands imcopy or imdel etc since these commands also keep track of all the housekeeping for the associated image les Checking Header Information It is useful at this point to check your headers to see that all looks well and more importantly that you have the right keywords describing the type of images in each case Initially this is a must since we are still working out FITS keyword assignments but soon this step will not be necessary unless of course you screwed up and recorded say an object frame which was really a dark frame or something else In this case you would want to go in and edit the appropriate keywords to keep IRAF from getting confused over which are which You can use ccdlist to get a brief review of your les or imhead with long yes to check out what s in their headers followed by hedit if necessary to actually make any changes For example to add the keyword IMAGETYP and set it equal to object in the header for solar imh you would do hedit solar imagetyp object ver or else do it from the epar route on hedit Setting the Instrument Parameters Once you are satis ed that you
70. lt j gt and lt k gt to move among the orders now identifying a decent sampling of lines throughout the orders I keep the Th Ar atlas by the keyboard at this point and just run through the format picking out the stronger lines and verifying that the wavelength predicted for each marked feature agrees to within 4 places with the atlas Whe done again type f for t dispersion Again use cursor and d key to zap out outliers and re t 50 HIRES Manual Instrument Description Once you feel sure that you have a solid preliminary solution you can let the routine nd many more lines automatically But this time increase maxfeat to 3000 to allow it to nd all the features contained in the linelist database But be careful if you haven t yet input enough correct line id s and or your match parameter is too large it can quickly nd many incorrect id s and head off toward an incorrect solution Use y to nd up to maxfeat features above threshhold and then lt l gt to match features to entries in the linelist database using the current dispersion solution Again when all the features have been identi ed type lt f gt to re t the dispersion Now with so many features it becomes time to tune in the order of the tting functions in x and y Again check your residuals and zap out outliers as needed Use xorder and yorder to vary the order of the t in either direction Use show to see the tting parameters and the
71. ng up the xhires and xpose control windows plus any other instrument status information windows desired by the user The HIRES CCD dewar gets lled automatically about once per day It is a good idea to note dewar level and decide whether an automatic may occur during 34 HIRES Manual Instrument Description the eveining observing hours The auto ll procedure does dump some cold into the spectrograph and probably moves the CCD dewar by a very small amount due to the added weight of the liquid nitrogen plus various thermal excursions in the surrounded metal structure For highest precision work I advise that one NOT allow an auto ll during observing Thus if an auot ll during the night looks probable take time in the late afternoon to force an auto ll before starting calibrations Section 3 Selecting a Spectral region Collimator choice The most fundamental decision a user wil have to make concerns optimizing the ef ciency of the optical train for the desired spectral region The rst choice in this regard concerns which collimator red or blue to use Consult the curves in Figure 5 for this choice Cross disperser choice The next decision concerns both ef ciency for the spectral region and desired order separation At present we have only one CD but this can be used in either 1st or 2nd order Most applications redward of 0 4 microns will use the 1st order while most blueward of here will use 2nd order Consult both the ef ciency c
72. ngle 70 4 Theta 5 0 DIAMETERS Collimated Beam 0 3028 mTelescope 10 90 m Collimator Focal Length 4 1547 mCamera Focal Length 0 7627 m CD GRATING 250 gr mm ORDER 1 Order Blaze A FSR A DEL mm DEL asec HEIGHT mm LENGTH mm DISP A mm 119 2994 8 25 2 0 510 3 958 55 026 28 94 0 87118 3020 2 25 6 0 518 4 025 54 512 29 18 0 88117 3046 0 26 0 0 527 4 094 53 989 29 43 0 88116 3072 3 26 5 0 536 4 165 53 458 29 68 0 89115 3099 0 26 9 0 545 4 238 52 917 29 94 0 90114 3126 2 27 4 0 555 4 313 52 367 30 20 0 91113 3153 9 27 9 0 565 4 389 51 807 30 47 0 92112 3182 0 28 4 0 575 4 468 51 237 30 74 0 92111 3210 7 28 9 0 585 4 549 50 658 31 02 0 93110 3239 9 29 5 0 595 4 632 50 068 31 30 0 94109 3269 6 30 0 0 606 4 717 49 467 31 59 0 95108 3299 9 30 6 0 617 4 805 48 855 31 88 0 96107 3330 7 31 1 0 629 4 895 48 233 32 18 0 97106 3362 1 31 7 0 640 4 988 47 598 32 48 0 98105 3394 1 32 3 0 652 5 084 46 952 32 79 0 99104 3426 8 32 9 0 665 5 182 46 293 33 11 1 00103 3460 1 33 6 0 678 5 283 45 622 33 43 1 00102 3494 0 34 3 0 691 5 387 44 938 33 76 1 01101 3528 6 34 9 0 704 5 494 44 240 34 09 1 02100 3563 9 35 6 0 718 5 605 43 529 34 43 1 04 99 3599 9 36 4 0 733 5 719 42 804 34 78 1 0598 3636 6 37 1 0 747 5 836 42 064 35 14 1 0697 3674 1 37 9 0 763 5 957 41 309 35 50 1 0796 3712 3 38 7 0 778 6 082 40 539 35 87 1 0895 3751 4 39 5 0 795 6 210 39 753 36 25 1 0994 3791 3 40 3 0 811 6 343 38 950 36 63 1 1093 3832 1 41 2 0 828 6 480 38 130 3
73. no refocusing A de tailed description of this camera was presented by Epps and Vogt 1993 Some sacrifice of image quality was necessary with this final design to accommodate at the last minute the unanticipated curved surface of the CCD 65 radius of curvature Backup designs featuring 12 6 micron rms image diameters over a 6 7 field of view with flat focal plane are also in place for the time when the flat CCD s become available 19 HIRES Manual Instrument Description Retrofitting to the flat focal plane design requires only fabricating and installing a new field flattener Corrector Lenses These lenses are made of Corning 7940 fused silica The front corrector lens corrector No 1 is a biconvex element and corrector No 2 is a meniscus These two large corrector lenses are heavy enough and thin enough that they sag under their own weight Finite Element Analysis FEA was done to design mounting cells which would remove most of this sag The lenses thus have push supports just outside their clear apertures which remove the sag and must be properly adjusted when re installing these lenses The corrector lenses are anttreflection overcoated with sol gel This sok gel AR coat is a dip coat process and is a very fragile overcoat It must never be touched The slightest touch such as lightly brushing with a sleeve etc will damage the coating These sol gel coatings can only be done at Lawrence Livermore National Labs and are thus
74. ns but presently assumes that the focus for guiding the deckers and for guiding off the slit are the same Calibration Lamp System A series of lamps are provided for wavelength calibration and flat fielding A Thorium Argon hollow cathode lamp is provided for the former and a quartz halogen 3400K incandescent source is provided for the latter A Deuterium lamp is also provided for flat fielding in the deep ultraviolet A solid state laser is also available It produces a very intense beam and is used only for alignment and scattered light experiments The laser actually produces a spectrum of intense lines spanning about one full order of the echelle Should an observer be so foolish as to attempt to observe the light HIRES Manual Instrument Description from this laser with the CCD they can expect to suffer the consequences not the least of which may be a very prolonged residual image All calibration lamps are housed in a light tight thermally insulated housing above the slit area The lamps are mounted on a translating table which runs parallel to the slit Figure 2 TV Camera Field 45 arcsec diam clear 4 60 aresecs passes through a defining stop which sets the size of the projected The calibration lamp optical system was designed to ensure that calibration light enters the spectrograph as similarly as possible as that coming in from the telescope at all wavelengths This is crucial for a
75. ntroller is based on the design described in Leach 1988 that utilizes a programmable digital signal processor to generate timing signals and manage communication with the host computer and allows remote programming of the timing waveforms and CCD clocking voltages The CCD clocks are generated with digital to analog converters while a 23 HIRES Manual Instrument Description conventional preamplifier dual slope integrator and 16 bit analog to digital converter process the CCD video signal All of the electronics are housed in a separate thermally insulated enclosure adjacent to the spectrometer This electronics enclosure is cooled via the ob servatory s recirculating coolant system Since we were obliged to use standard observatory VME electronics modules which are not rated for use below 0 C we will actually be holding the electronics enclosure at a temperature of 5 C Software Control System The software for instrument control at Keck Obser vatory is written in programming language and runs under UNIX on a network of Sun computers The observer controls a given instrument through a software user interface which allows both command line input through keywords and scripts and window style graphical input using X11 windows with the MO TIF toolkit Both types of input can be intermixed The user interface also allows for multiple invocation of control processes which is important for distributed observing Here the prima
76. o the directory u vogt IRAF demo The data frames to be used in this sample reduction are solar ts a 100 second observation of the solar spectrum quartz the spectrum of a quartz halogen incandescent lamp dark ts an 1800 second observation of the dark level in the spectrograph zero ts a zero length 1s exposure on dark to determine bias levels thar ts a 1 observation of the Thorium Argon hollow cathode lamp used for wavelength calibration Note that for full blown data reductions one might well have several zero frames several quartz frames and several dark frames These would then be combined into more noise free calibration frames by median ltering out cosmic rays by simple 37 HIRES Manual Instrument Description averaging to reduce readout noise and by suitable interpolation if necessary between bracketing calibration exposures There are a number of strategies which can be used within IRAF to combine calibration data frames to squeeze out the last bit of instability from the instrument as needed for the particular project Note also that these frames could and generally would end up with much more abstract names such as n0045 ts data0131 ts when read into the subdirectory in which you plan to work If they do you might wish to consider changing their names before you get started to more obvious descriptions of what they represent so that you don t get confused later
77. orders to allow for adequate sky sampling a factor which can become quite important in bright or grey time when pushing to faint limits This interorder room could also be used for image slices though image slicers have not been provided as of this writing HIRES Manual Instrument Description Chapter 2 Instrument Description The HIRES instrument sits permanently on the nght nasmyth platform of the Keck I telescope It is enclosed in a thermally insulated light tight dust tight room which is kept under clean room conditions A word of warning is necessary here Access is restricted solely to authorized Keck personnel All personnel entering the HIRES enclosure are required to don appropriate cleanroom garb full suit booties cap and mask It should never be necessary for astronomers or other users of HIRES to enter the enclosure Indeed entry by unauthorized or untrained personnel is likely to result in damage to the HIRES optical components and also to the person entering there are powerful remotely controlled mechanisms which can move without warning HIRES is designed to be run remotely either from the control room at the telescope from Waimea and also from just about anywhere in the world over the Internet It can also be run from multiple locations simultaneously such as shared observing by a collaborating group Section 1 Summary of Characteristics Before discussing the principal components of HIRES it seems usef
78. ow displayed If totally lost as to what to do next from the tektronix plot window just type lt gt and you ll get a help summary But you must q twice out of the help summary to get back to interactive mode in the tektronix window Useful commands to play around with in interactive tting of the baseline or for many interactive tting tasks are high high reject level sigma units low low reject level niter number of iterations order and show to display these parameters Try to get as low order of a spline as possible that ts the baseline reasonably well When done type q to quit out of each interactive tting session and move on to the next frame to be baselined When all nished in ccdproc go take a look at your les with ccdlist and you should see all the processing operations that have now been done on them along 41 HIRES Manual Instrument Description with the dates of when the operations were done This may begin to give you a warmer feeling that something useful is now happening to your data Tracing the Echelle Orders The next step is to use the quartz spectrum to locate the positions and track the shapes of all the echelle orders We generally use the quartz since it is a nice high S N smooth spectrum with easy to nd orders But one could use a spectrum of a star or some other reference if desired The point is that you want the echelle orders of this reference frame to correspond as closely as possi
79. own well below a pixel by this point If you already know which order corresponds to a given aperture you can use the o option in t to set this If you are not setting the order number directly check to see if it solved correctly for the order offset the offset between your aperture number and the true interference order at the echelle If it got the offset correct this is a good indicator that you are on your way to a solid and correct solution Be careful though it could still be off slightly in echelle order you may need more features to really nail this down Now you can type lt q gt to quit out of this tting subroutine and return to displaying the orders again You can now either manually hunt down and mark other features to improve the t or quit out and write your initial solution to the database To identify other lines quickly by hand say by looking at the Th Ar atlas simply move the cursor near a line and hit spacebar to mark the nearest line It will then prompt you with the pixel position and the computed wavelength from the current solution If this computed wavelength matches within a window set by the match parameter a line in the linelist database it will return the tabled wavelength Otherwise it returns with INDEF and waits for you to input a wavelength If you are happy with its tabled wavelength just hit return This enormously speeds the entering of many more lines to really pin down the dispersion t Use
80. ping dirt and airborne contaminants out of the slit area so please keep it closed when the instrument is not in use Atmospheric Dispersion Compensator ADC An atmospheric compensator ADC will eventually be installed though there will not be one at first light Since the HIRES slit will not in general lie along the parallactic angle losses particularly in the ultra violet could become substantial at the slit if atmospheric dispersion is not correctly accounted for in the guiding A guiding option which calculates and correctly offsets for atmospheric dispersion is available though of course is not as effective as the eventual ADC unit will be Image Rotator An inage rotator has also been designed for HIRES but has not yet been funded So no image rotation will be available at first light The consequences of not having control of the position angle of the slit on the sky should be carefully considered when planning and executing observations TV Acquisition Guide Camera A Photometrics CCD TV is provided for object acquisition and guiding A Canon 200 mm f 1 8 lens provides a 45 arcsec by 60 arcsec field of view centered on the entrance slit CCD TV pixels are about 1 6 arcsec square but can be made bigger by on chip binning if desired with no increase in the field coverage of course A view of the slit area with the TV camera field is shown in Figure 2 Here one sees a portion of decker plate A overlying the widely open slit
81. rms t You can watch the rms t statistic as you play with xorder and yorder to decide upon the best compromise Try always to use the lowest order number possible consistent with the desired or expected tting accuracy In my limited experience I have found that 4 works well for both xorder and yorder and rms ts of 0 0022 Angstroms are commonly achieved You can also display your tting residuals in many other meaningful and entertaining ways by using the x and y keys to rede ne the abcissa and ordinates of the residual plot Try yo and then xp to show a map of where all your identi ed features were located Check for areas clusters where many points may have been deleted If necessary you may have to go back in and pin down more lines in these areas Try yv and xw to show velocity residuals with wavelength etc When convinced that the solution looks solid and correct quit out and save what you ve done to the database Next time through near this position on the format you can we this spectrum as a reference and use ecreidentify to do the wavelength solution quickly and painlessly You are now done computing the wavelength solution for the Th Ar reference spectrum Attach Dispersion Solution to the Solar Spectrum We must now use the task refspec to attach the dispersion solution just found for the Th Ar reference spectrum to our program object spectrum solar ds ec imh Here is the parameter le for this Image R
82. roughput slit width times resolving power product is about 39 000 arcsecs The slit must be used with one of the notches in Decker Plate A to de ne slit length and keep orders from overlapping If instead the user wishes to use one of the apertures from Decker plates B D which de ne both slit width and length the slit must be opened fully to keep it from blocking any light This is done at present by doing the command m slitwid 11 1 but will eventually be an option in xhires slit length Slit length de ned either by one of the notches in Decker plate A or by one of the apertures on the other decker plates must be chosen according to the available order separation at the spectral region of interest and the need for sky 35 HIRES Manual Instrument Description subtraction Consult the echelle format simulator for the minimum order separation available in your chosen spectral region and set the slit length to be less than this If sky 15 not important to measure a slit length only a bit bigger than the seeing disk 15 adequate However it is generally prudent to make the slit length as long as possible to measure as much sky as possible but short enough such that one still leaves rooom for some rows of dark between orders decker vs slit considerations The guide star image looks much worse when guiding off the slittdecker A combination than it does guiding off a simple decker Thus for faint object work use of the dec
83. rving run A detailed description of the HIRES echelle format simulator can be found in Steve Allen s user s manual which is published as UCO Lick Technical Report No 68 But if you don t happen to have a copy of that manual in hand simply reproduce with my own comments added much of the user interaction section from Steve s manual here The executable code for the simulator will reside on the Keck Observatory computer system Observers will have to get guest accounts at Keck to access this code Alternatively binary versions of the code running under SunOS may become available from UCO Lick Observatory and can be FTP d to the user s institution The most common platform on which the instrument simulator will be used is probably a high resolution monitor running version 11 of the X Window System from MIT However it is essential to note that the instrument simulator 15 NOT 11 program The instrument simulator uses the Lick Mongo package to do its graphics and user interaction 25 HIRES Manual Instrument Description This allows the instrument simulator to be run on a variety of platforms dating back to Tektronix storage tube terminals Because of this the instrument simulator cannot do multiple popup windows and menus as would be expected of a modern X11 based user interface Section 1 Before starting some words about Con guration Files The simulator is a general purpose tool which requires con gurat
84. ry observer can le quite remote from the telescope i e in Waimea or back in California while graduate students and or technical observers at other sites or at the mountaintop can cooperate in the set up and running of the instrument during an observing run The primary tool for interacting with HIRES is a graphical user interface called xhires It is a self explanatory click on icon pop up menu style control interface It can be run in active mode where it will actually move spectrograph parts or in simulator mode not connected to the real spectrograph The simulator mode is very useful for practicing before actually going out for a run and instrument set ups can be generated and saved for use later during observing Al Conrad aconrad keck hawaii edu wrote xhires and is the contact for this software 24 HIRES Manual Instrument Description Chapter 3 The HIRES Spectral Format Simulator Like most echelle spectrometers the spectral format is larger than the available detector real estate The HIRES optical system was designed to feed a 2 by 2 mosaic of Ford Loral 2048 CCD s This mosaic would have been some 61 mm on a side What we ended up with at frst light was 49 mm square Tektronix CCD When the length of the free spectral range of any echelle order is longer than the 49 mm dimension of the CCD holes will appear in the data since those regions of each order falling off the CCD imaging area will not be recorded These
85. s Subset translation file graphic stdgraph Interactive graphics output device cursor Graphics cursor input version 2 October 1987 mode ql A crucial parameter here is pixelty which must be real for both output and 39 HIRES Manual Instrument Description 51 calculation types This does eat up more disk space but you run the risk of data over ow if you don t do this Note that the instrum parameter is already set up for you When done with this parameter list exit by typing g to exit and execute This will move you over into the epar mode in the ccdproc task of the ccdred package CCDPROC You will now be in the epar mode of the task ccdproc Image Reduction and Analysis FacilityPACKAGE ccdredTASK ccdproc images solar quartz thar dark zero List of CCD images to correct ccdtype object CCD image type to correct max_cac 32 Maximum image caching memory in Mbytes noproc no List processing steps only fixpix no Fix bad CCD lines and columns oversca yes Apply overscan strip correction trim yes Trim the image zerocor yes Apply zero level correction darkcor yes Apply dark count correction flatcor no Apply flat field correction illumco no Apply illumination correction fringec no Apply fringe correction readcor no Convert zero level image to readout correction scancor no Convert flat field image to scan correction readaxi line Read out axis columniline fixfile File describ
86. s There is no attempt to thermally control the nterior temperature Rather it is expected to track the dome interior temperature from day to day but not from hour to hour A slow flow of filtered and dried dome air is continually forced into the enclosure through a hose and adjustable valve that is the hissing noise you always hear when inside All attempt has been made to keep all sources of heat out of the interior of HIRES and not to dump heat into the dome Most of the control electronics are contained in a separate Electronics Bay a similar style thermally insulated enclosure and heat inside the electronics bay is carried away by the observatory s recirculating liquid coolant system Electronics inside the HIRES enclosure which drive the CCD and other electronics which control the TV camera are contained in their own thermally insulated footlockers These footlockers are also cooled by the observatory s coolant system psuedo clean room ante chamber is also provided Personnel entering HIRES will be required to don appropriate clean room garb in this ante chamber Dust accumulation is a serious concern for HIRES and personnel entering HIRES are expected to do all they can to eliminate dust and dirt particularly that brought in on shoes Sticky mats get a lot of it and must be renewed frequently But even the mats do not get it all Clean room suits with booties are thus mandatory Electronics Control System The control
87. se of the need to block 3rd order In 181 order a wavelength span of twice the bluest wavelength will be possible if there is enough CCD real estate A plot of the efficiency of the CD is presented in Figure 6 Because of the above mentioned blaze angle error the efficiency of this CD below 0 35 microns will be somewhat lower than hoped A new Ist order CD blazed for 0 39 microns and with 395 grooves mm is being manufactured to correct this situation Like the echelles the CD is housed in a dust tight enclosure Since these gratings can never be cleaned one should never attempt to touch them or even to get near them And their cover should be kept closed when not in use 18 HIRES Manual Instrument Description Figure 6 Cross disperser efficiency curves HIRES CD MR122 1 2 250 gr m 5 degree blaze angle 40 deg included angle average of S and P polarization Absolute Efficiency 0 2 03 04 05 06 07 08 09 1 0 WAVELENGTH microns Camera The camera is an all spherical f 1 0 polychromatic catadioptric system It uses two corrector lenses an f 0 76 primary mirror and a thick meniscus field flattener which also serves as the dewar vacuum window This style of camera is extremely achromatic The camera delivers 21 6 micron rms diameter averaged over all field angles and colors images over a 5 2 diameter field of view over a spectral range of 0 3 to 1 1 microns with
88. ser would be quite useful for QSO work Or a coarser echelle could be used to provide shorter orders in the red and near IR to avoid gaps in the spectrum The addition of each new echelle or cross disperser is relatively expensive but easy to fund from individual research grants if the science warrants The rst addition will be probably an image rotator This is quite necessary for highest performance of the instrument when doing long exposures on faint objects both to compensate for eld rotation and to eliminate light losses at the slit from atmospheric dispersion The prob lem of atmospheric dispersion of point like objects can be overcome by using the rotator to set the HIRES slit along the parallactic angle such that the dispersed image lies along the slit Field derotation 61 HIRES Manual Instrument Description will also be required for long exposures on gravitationally lensed QSO s Ultimately an atmospheric dispersion comper sator must also be provided as well to provide dispersion compensation on lensed QSO s or other extended objects When probing the chemical abundances of globular cluster members multi ber input feed would be quite desirable and would yield enormous speed gains in the multiplexing Probably the ber head would feed both HIRES and the Low Resolution Imaging Spectrograph LRIS HIRES bers would terminate at the curved focal plane of a spherical collimator which would drop down in front of the normal collim
89. slit width is varied The slit jaws cannot be closed completely since this would damage their sharp edges Slit width can be specified either in microns in seconds of arc as projected on the sky or in pixels as projected on the CCD A wide opened slit is about 11 1 mm Behind The Slit Filter Wheels There are two 12 position filter wheels behind the slit These are primarily for blocking unwanted orders from the cross disperser Eleven Height Width arcsec arcsec 11 HIRES Manual Instrument Description positions are for 2 by 2 square or 2 diam round filters while position No 1 is a long narrow clear slot and cannot be loaded with a filter Table 4 shows filters currently available Filter positions marked clear are empty and can be used temporarily for a user s personal filters Personal filters may only be loaded by the Keck technical personnel and should be removed at the end of one s run If users wish any filters to be permanently added to the selection please contact S Vogt Table 4 HIRES Filters 6 5893 30 Proper choice of order blocking filters absolutely crucial to one s success in isolating any particular spectral region of interest Ultimately the user must 12 HIRES Manual Instrument Description Table 5 Some useful lter combinations Order Range microns 1 Position 2 Position 1 2 pon 12 peos 3006339 h esos 0
90. st of filters available in the comparison lamp system is given in Table 2 Position 1 vignets the beam and should never be used Position 11 contains the Fabry Perot etalon used for wavelength calibration Position 12 is presently open and available for public use though loading one s favorite filter can only be done by a qualified technician and does take some effort and time Table 2 Lamp Filters UGS Imm UGI ima BGI2 mmy Table 2 Continued Lamp Filters 0 C 2 The light from the calibration system is fed into the HIRES optical axis by a feed mirror which automatically slides into place in front of the slit when calibration lamps are requested When stowed this mirror retracts into a dust tight housing off to one side The mirror has angular adjustments which allow the calibration system pupil to be aligned with the telescope pupil The adjustments must only be made by a qualified technician HIRES Manual Instrument Description Iodine Absorption Cell An iodine absorption cell can also be slid into position directly in front of the slit This cell is basically a sealed glass bottle with a small amount of iodine crystal within When heated to a temperature above 35C the iodine sublimes and the gas then produces an absorption spectrum on the beam from the telescope as it enters the spectrometer The iodine absorption spectrum is a rich forest of deep very narrow lines This forest of lines starts at
91. stances these capabilities are not desired by the user and they are disabled ooro 32 HIRES Manual Instrument Description WAVLMIN MinDispWavel ECDELTAD 33 HIRES Manual Instrument Description Section 4 Command Line Interaction When the user has quit from the graphical interaction by simply typing q while in the graphic window the program enters another mode where the interaction is done on the text screen All commands in this mode must be followed by a carriage return lt CR gt R Refresh graphies and rom 1o gt Wit KICS stp Mew disk and Chapter 4 Preparation for Observing This section is not yet written Some possible items for inclusion are 1 checklist for caveats on program object observability etc 2 nder charts coordinates offset stars 3 blind offsets and faint object acquisition and guiding 4 choice of targets 5 choosing wavelength ranges resolutions sky sampling 6 estimating exposure times 7 common acquisition observation problems 8 running the simulator creating and uploading set up les 9 plan on arriving early 10 remote observing 11 pre observing run checklist Chapter 5 Observing at Keck Some of these sections are not yet complete Section 1 Arrival at the Mountain top Section 2 Starting Up the Instrument The mountain staff will take care of starti
92. system for HIRES is a VME based system which uses only Keck Observatory standard modules HIRES is one of an initial complement of five first light instruments which connect to a scientific instrument LAN at the mountaintop Each instrument is controlled by its own VME bus based Sun 3E 68020 CPU realtime controller running VxWorks which connects over the scientific Ethernet LAN to either of two SUN Sparc series instrument computers The main instrument control computer for HIRES is makua keck hawaii edu Another Sparc station lanikai keck hawaii edu is also used during HIRES observing primarily for data reduction and analysis Since there are multiple instrument computers two or more separate instruments can be electronically online at the same time as will often happen as one team prepares an observing run following another One instrument computer also serves as a back up for the other The instrument computers are then connected to the Keck Observatory Ethernet LAN which provides a link with similar computers at the headquarters down in Waimea The HIRES VME chassis includes one SUN 3E120 CPU card one SUN 3E340 Ethernet card eight Galil DMC 330 10 Motor controller cards three XYCOM XVME 212 input port cards three XYCOM XVME 220 output port cards and one XYCOM XVME 540 Analog logic card Most moving mechanical devices are driven by Galil DC servo motors Each optical instrument which uses a CCD has its own CCD controller system The CCD co
93. ther FSR in grey on either side of the blaze In the case of an Echelle 27 HIRES Manual Instrument Description spectrograph with grating cross dispersers the simulator displays the selected order of cross dispersion and several nearby orders of cross dispersion Any spectral lines which were de ned are plotted on the Echelle format twice The position of the spectral line closest to the blaze is drawn with a dot and the position next closest to the blaze is drawn as open dot It will usually be best to choose to observe a spectral line in the order where it is closest to the blaze since that will be where most of the light at that wavelength is located The secondary line locations are shown for cases where the Echelle format is large compared with the detector Information concerning the blaze wavelength and or order number of each echelle order can be toggled onto or off of the display by clicking on appropriate menu items The simulator also draws a schematic of the detector s properly positioned on the Echelle format Any bad spots on the detectors are indicated by rectangular regions on the display If you are windowed down to some subset of the CCD the readout regions are indicated by dotted lines The simulator also displays text lists which give the details about the optics their settings and the current location of the cursor At this point the simulator is ready for interactive graphical use 28 HIRES Manual Ins
94. trument Description Figure 8 Typical appearance of the Simulator during interactive use Other Menus Optical HW All Setup DetectorMosaic Refresh All ZoomOrDetector Setuphame twoamp Observer E Tilt deg1 1 265 X Tilt deg 0 000 ight Deck Fgt m1 0 001000 Deck 1 1 379 Slit bkid m120 001000 Slit 12 1 1 379 SlitWid pixJ 4 614 SlitVellm sl 9619 7 1 Xa dea 25 34 X binring 1 Curs 5403 9 EchOrc 66 abl AJ 5401 7 0 030 Disp A mm 1 57 SepL 1212 97 1 68 0 1 31 66 Len mr 52 288 Chip Fixelz 1 193 1 2361 DeckHet pix1 7 224 413820 32 077 Most of user interaction with program is accomplished with single keystrokes or mouse clicks while the graphics are displayed Many of the possible commands are visible Section 3 Graphical Interaction on the menus at the left side of the screen The scarcity of screen real estate on some types of displays prevents all possible commands from being visible There are 3 methods by which the user can graphically interact with the program 1 2 3 Accelerator Key Mouse Drag Menu Click 29 HIRES Manual Instrument Description A glance through the following tables will reveal that some parameters may be modi ed using more than one of these methods A
95. uction of echelle CCD images Read it carefully before starting any reductions In fact a careful read through before observing will give you a much better feeling for what kind of calibration frames to obtain with your program object data and how they will be used I will now try to walk you through a very basic set of reductions on a typical data set from HIRES This will be only a simple example but will illustrate many of the most important aspects of the data reduction I will assume you are generally familiar with running IRAF in using its eparameters feature in nding your way around within its libraries of routines and understanding what kinds of data it creates and where such data lives Getting set up with data in the appropriate directory I will also assume that you have logged onto some Sun Sparc station running X11 windows with the latest version of IRAF installed and that you have moved over into some directory which contains your images This directory will also end up containing as subdirectories all the databases etc generated by IRAF when it munches on your data I like to break my directory up as IRAF in the top level and then subdirectories containing groups of data les which are to be combined together in a reduction For this example I will assume we have obtained a group of exposures of the day sky solar spectrum plus calibration spectra at some place in the echelle format and that these data les have been put int
96. ul to briefly list a summary of HIRES characteristics and capabilities 1 Spectral range 0 30 to 1 1 microns 2 Spectral resolution up to 84 000 3 Slit length up to 28 arcsecs Defined by a selection of deckers 4 Typical spectral span per exposure 1200 to 2500 A 5 Order separation 8 to 43 arcsecs 6 Resolving power times slit width 39 000 arcsecs 7 Detector Tektronix 2048x2048 CCD 24 micron pixels 8 CCD readout noise 5 6 electrons rms 9 CCD dark current lt 10 e pixel hour 10 2 pixel projected slit 0 60 arcsecs 11 Image de rotation none 12 Atmospheric dispersion compensation none 13 Acquisition and guiding fixed Photometrics CCD TV staring at a 45 arcsec by 60 arcsec field centered on the entrance aperture 14 Calibration sources quartz halogen Deuterium lamp Th Ar hollow cathode Iodine absorption cell Edser Butler FP diode laser Section 2 Description of the Light Path A simplified schematic of the HIRES instrument is shown in Figure 1 This figure was also used as the model for xhires the graphical user interface through which the user controls the instrument It is well worth studying this conceptual diagram and using it as a guide HIRES Manual Instrument Description when setting up the instrument When configuring HIRES for a given observation I like to go through this diagram as a photon travels element by element checking the options for and settings of each elem
97. ult whereby extracted spectra keep the same name but with addition of a ec exptension Again we will be using the quartz imh image as the reference for apertures Also for this run we will not be extracting sky since there really is none in these data We will do a simple sum along columns in the aperture window for this extraction but of course more complex extractions such as optimally weighted summation can also be done here You should review each extracted order interactively or use splot to again sanity check for correctness Wavelength Calibration We will now use the task ecid to do a wavelength calibration using the thar ec imh spectrum IRAF has a catalog of some 3000 Th Ar lamp emission lines and will use this information in conjunction with the many line positions found in your thar reference spectrum to compute a very accurate wavelength solution for each order You might wish to obtain a copy of A CCD Atlas of Comparison Spectra Thorium Argon Hollow Cathode 3180 A 9540 A Willmarth 1987 from NOAO It is helpful for recognizing and indentifying features in your Th Ar spectrum Unfortunately it doesn t look that similar to the speci c lamp used in HIRES so don t expect line strengths or line strength ratios to be the same Only line spacings can be trusted and some lines won t even be there A better aid is the Th Ar atlas ve are currently working on taken with the actual HIRES lamp Graduate student Mike Ke
98. ures you just found in apall be sure not to nd recenter resize or edit the aperutres When nished you should do a sanity check using the task display to display atimh and visually inspect for unexpected results etc You should have nice uniform intensity quartz spectrum orders with lots of clear dark space in between If you histogram equalize the image you may also be able to see the meteor which is a scattered light feature of the spectrograph It generally runs diagonally across the chip and is brightest when crossing each order You will also see the prominent dark blob near CCD center Again if you need hardcopy output use the print button under the etc menu in SAOIMAGE Flat Fielding the object images With the normalized at eld image in hand from the previous step you are now ready to use the task atten located in the generic package to remove the high spatial frequency pixeLto pixel response variations We will at eld correct both solarimh and thar imh using the at eld image atimh attening routine resides in a package called generic so load this 45 HIRES Manual Instrument Description package by typing generic and then epar into atten The parameter list for atten should look like this IRAFImage Reduction and Analysis FacilityPACKAGE genericTASK flatten images solar thar Images to be flattenedflatfiel flat Flat field minflat INDEF Minimum flat field value pixtype real Flattened image
99. urves of Figure 6 and the HIRES spectral format simulator for this decision Order blocking lters Once the CD order decision is made you will have to think carefully about how to block unwanted orders from the CD Here Table 5and Figures 3 and 4 will help in this decision Once these lters are selected the collimator will be automatically refocussed for the new thickness combination Section 4 Choosing the Entrance Aperture slit width The user must set the slit width to give the desired spectral resolution Basically the de projection factor from actual slit width to projected slit width in the echelle dispersion plane at the CCD is about 1 8 715 which results in a scale of about 12 44 arcsecs mm at the CCD in the echelle dispersion direction The present CCD pixel size is 24 microns or 0 024 mm Thus a 2 pixel projected slit is about 0 60 arcescs wide as projected on the sky The resultant spectral resolution will be some thing like a gaussian quadrature sum of the projected slit the pixel size and the camera aberrations blur circle Effectively this 0 6 arcsec slit translates to a spectral resolving power of about 54 000 60 000 A 0 9 arcsec slit width projects to about 3 pixels width and results in a resolving power of about 45 000 A 1 1 arcsec slit projects to 4 pixels width and yields a resolving power of about 34 000 In the limit of larger slits where camera aberrations and nite pixel widths are small the effective th
100. x CCD Quantum Efficiency Quantum efficiency 02 03 04 05 06 07 08 09 10 wavelength microns Dewar Focus Fine focus of the camera can be done by using the dewar focus mechanism This mechanism moves the entire dewar CCD plus field flattener along the camera axis Total travel is only about 0 03 but with very high precision The camera is so fast f 1 0 that some care is required to get proper focus Focus errors of 0 001 may degrade spectral resolution unacceptably A powerful focusing algorithm is being developed which should assist the user in this task At some point it will probably be possible to fully automate the focus procedure The camera frame is a thermally stabilized design and camera focus should thus not be a function of temperature During the first 4 months of HIRES use we have not seen any reason to refocus the camera but it should be periodically checked Focusing can also be done using the collimator focus and refocusing for various thickness filters etc will generally be done using the collimator focus Changes of X in collimator focus are equivalent to changes of X 30 in camera focus Enclosure Electronics Bay and Clean Room Ante Chamber The spectro graph is enclosed in a modular insulated light tight dust tight housing This housing provides 22 HIRES Manual Instrument Description about a 9 hour thermal time constant between inside and outside temperature

HIRES USER`S MANUAL - WM Keck Observatory

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