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Processing TRES data begins by making and going to a date-specific
processing directory separate from the raw data directory. Then all
of the spectra taken in a night are sorted by type, configuration,
and exposure time.
Bias and dark frames are processed by configuration and are used to monitor instrument performance, but not currently for anything else, though they may be optionally subtracted from all flat, comp, and object spectra.
Flat fields are processed to get templates for spectrum extraction, apflattening correction images, scattered light correction masks, and echelle blaze correction spectra.
Thorium-argon comparison lamp spectra are extracted using the flat template and cross-correlated against a reference spectrum with a known dispersion. The shift is applied, and the dispersion function is refit optionally interactively for the first spectrum of a configuration and fiber. Pixel dispersion shifts through the night are tabulated.
After all of the night's calibration files are set up, TRES is such a stable instrument that object spectra can be extracted and calibrated automatically with a single command.
0. Start IRAF and load the tres package by typing ecl> tres #-----------------------------------------------------------+ # TRES Data Reduction Package | # Smithsonian Astrophysical Observatory | # Telescope Data Center | # Version 1.3.6 July 24, 2009 | # Processing steps at | # http://tdc-www.harvard.edu/instruments/tres/reduce.html | #-----------------------------------------------------------+ btres tcal tflatlist tmakemask trsavg trsproc ctres tcal1 tfset tmakeref trscode trssum dtres tcemsao tgcomp tmaskfile trsdate tscat ftres tcosmic tharadd tmodid trsdb tsetbcv otres tdata tharlist tmonth trsdecode tskysub qtres tdir tharplot tpmake trsdump ttres skyplot tdisp tharset tpreamp trsfiles tvxcsao stres tdispref thartable tpreproc trsgroup txdelete tapref textract thistogram tproc trslist txdisp tarith tfib tidref tpxcsao trsmed txhead tbias1 tfib1 tlog tquick trspec txstat tblaze tflat tmakeflat trelearn trsplot tres> If the banner message says *** Run trelearn to update parameters *** type tres> trelearn If this task crashes, run it again. I haven't figured out how to deal cleanly with deleted parameters, but added parameters will now appear in your parameter files with their default values. 1. Go to the processing directory for the date you wish to process tres> trsdate yyyy.mmdd will put you in the correct working directory. The date is saved as a parameter, so if you have to leave IRAF for some reason, or make sure that you are in the right directory, all you have to to is type tres> trsdate Date for images (now=today) (2009.0311): [return] tres> pwd /home/user/tresq/2009.0311 2. Make lists of similarly configured files. tres> trsgroup> If trsgroup.redo=yes, the default value, old lists and the data.db file will be deleted and a new, updated data.db file and derived lists will be written. Useful lists for the most commonly used medium aperture, binned by 2b configuration include: BIASmbNNx0.0.list DARKmbNNx600.list and/or DARKmbNNx900.list FLATmb1FNx0.1.list FLATmb2NFx0.1.list COMPmb1CNx0.5.list COMPmb2NCx0.5.list 3. Check bias files tres> btres BIAS__NNx___.list Run btres on lists of similarly configured bias files (BIASmbNNx600.list, for example). A file called "bias"|apsize|binning".fits" (i.e. "biasmb.fits") will be created. I check the bias count distribution by running the thistogram task on these files. 4. Check dark files tres> dtres DARK__NNx___.list Run dtres on lists of similarly configured dark files (DARKmbNNx600.list, for example). A file called "dark"|apsize|binning".fits" (i.e., "darkmb.fits) will be created. I check the dark count distribution by running the thistogram task on these files. 5. Process flat field files tres> ftres FLAT__1FNx0.1.list tres> ftres FLAT__2NFx0.1.list Run ftres on lists of similarly configured flat files for each aperture (FLATmb1FNx0.1.list and FLATmb2NFx0.1.list, for example). The list of files will be processed and combined according to the ftres parameters. Currently, I use cosmic=no and sumspec="median" to removed cosmic rays without being affected by shifts in the cross-dispersion direction. The resulting file is used as an aperture template using aptrace. I usually run interact=yes so I can check the traces. A resulting aperture mask file, "flat"|apsize|binning|fiber|".fits" and its associated database/ap file, as well as a flattening file, "flat"|apsize|binning|fiber|".flat.fits", will be created for each input list. The task which is called by ftres to make these files from the reduced flat field image is called tmakeref. Here is an example of how it runs. When you run the second fiber for a given configuration, the two flattening files will be combined into a single one, "flat"|apsize|binning|"12.flat.fits", and a mask file for removing scattered light, "flat"|apsize|binning|"12.mask.fits", will be derived from it. Scattered light will be removed from each flat image using that mask file, and spectra will be extracted from the corrected image. Those spectra, one per fiber, are normalized by their mean and used to remove the echelle blaze function from object spectra. Two blaze correction files, "flat"|apsize|binning|"1n.fits" and "flat"|apsize|binning|"2n.fits" are created. After wavelength calibration files are processed, the blaze correction spectra can later be dispersion corrected and made into a spectrum of the relative throughput between the two fibers using tpmake. The background removal task, tskysub will call tpmake if the throughput correction file is needed and not yet made. 6. Process Thorium Argon wavelength calibration files tres> ttres COMP__1CNx0.5.list tres> ttres COMP__2NCx0.5.list Run ttres on all of the exposures of each fiber of each configuration. You should run the longest exposure first, if there are multiple exposure times for a configuration. I have been using the first exposure of the night as the reference from which a running offset is computed. To set a medium fiber binned standard, for example tres> cat COMPmb12.list 0035.COMP.fits 0036.COMP.fits 0037.COMP.fits 0062.COMP.fits 0096.COMP.fits 0124.COMP.fits tres> ttres COMPmb12.list compstd="first" compid+ compstd="first" will run tcal1 to fit dispersion functions for both apertures of the first calibration file using a default ThAr spectra. compid+ will put you in interactive mode to examine the lines which are found and the fit the ecidentify task gets to them. Later ThAr spectra in the list will use that first solution as the reference and run reidentify after cross-correlating multiple orders in pixel space to get a shift in wavelength which is then tabulated in a file called "comp"|apsize|binning|fiber".shifts" You can check the dispersion function by labelling major ThAr emission lines: tres> tharplot [compfile].ec.fits 7. Process object spectra. tres> trsproc o trsproc runs otres on lists of similarly configured object spectra. Simply edit the list of lists, "obj.list", to just the files for which you want spectra, commenting out the others by prepending a "#" to the line with the name of the file containing the list of files for the undesired object. otres can be run on individual object .list files, too. 8. To cross-correlate all (or most) of the orders of a resulting spectrum against a template, use the tpxcsao task to do it in pixel space or tvxcsao to do it in velocity space. I run twilight skies (object=SOLAR) against each other as a test.