Astronomy 920 Commissioning of the Prime Focus Imaging Spectrograph

1. Astronomy 920Commissioning of the Prime Focus Imaging Spectrograph Meeting 7 SALT IRAF Package Ken Nordsieck Ast 920 Meeting 7

2. PFIS First Light Night NGC 1866 (LMC) 6290 Interference Filter 5 sec Ast 920 Meeting 7

3. Quiz Question • Why did we go to all that expense to get large diameter etalons? Ast 920 Meeting 7

4. Scanning • PFIS control system allows arbitrary sets of discrete steps (equal exposures) • linear scan for line profiles • dithering onto continuum for absorption lines • Off axis, must take account of wavelength gradient due to cos θ center to edge gradient: λ(r)/ λ0 = 1/ cos θ ~ (1- .00365*(r/4’)2 ) (24 Ang at Hα) • Inside “bullseye”, wavelength changed by less than resolution: D(bullseye) = 1.4’ (10,000/R)1/2 - if object larger than bullseye, extend scan to cover same wavelengths - if object not round, pays to move telescope and rescan, instead of extending scan Ast 920 Meeting 7

5. Accessing SALT IRAF package • Source (environment variable $salt) • Unix: /usr/local/salt • MAC: /usr/local/iraf/irafext/salt cl> salt [ loads salt task ] cl> help pfis [ lists pfis commands ] cl> pfis [ loads pfis subtask ] cl> cd working directory/yyyymmdd Ast 920 Meeting 7

6. PFIS commands PFIS/ SALT IRAF Package Hierarchy implemented lower level pprepare p pireduce r pmosaic m imcoadd pgainpbiaspsreduce ps pstransform t psskysub s psextract e scombine piflat psflat pswavelength pscalibrate c psstandard pbpm pscut • Raw data • name: Pyyyyddddssss.fits, ie P200510200079.fits • "multiextension" fits file, one for each of 6 amplifiers; open in DS9 with "open other/ open mosaic IRAF" • Each stage of processing prepends a letter or two • Imaging: (pireduce, pmosaic) mrpP200510200097.fits • Spectroscopy: (psreduce) psP2..... Ast 920 Meeting 7

7. Imaging • pprepare (p) • check header validity, • get data from calibration database • pireduce (r) • remove crosstalk • subtract mean of overscan in each amp, trim • divide by gain for each amp • subtract bias, if specified • subtract dark, if specified • divide by flat, if specified • pbias: run pireduce on bias frames, bias/ dark/ flat turned off • pflat (TBI) run pireduce on flat frames, dark/ flat turned off • pmosaic (m) • combine amplifiers and ccd's into single fits files • can now be opened as normal image by DS9 • imcoadd (TBI) • remove distortion • combine mosaiced images, registering and removing cosmic rays Ast 920 Meeting 7

8. Spectroscopy • psreduce (ps) • run pireduce • run pmosaic • using slitmask definition file (MDF), cut into one piece for each slit (pscut) • apply first guess wavelength calibration to each • psflat (TBI) run psreduce on spectral flats (tungsten continuum spectrum) • pswavelength identify lines and update wavelength dispersion calibration for wavecal frame • pstransform (TBI) resample cut spectra onto linear wavelength vs space grid • psskysub, psextract (TBI) extract to 1-d raw spectra • pscalibrate compute flux cal from flux standard Ast 920 Meeting 7

9. Configuration Data • Instrument configuration data: $salt/pfis/data (IRAF pfis$data) • PFISamps gain and noise for ccd amps • PFISxtalk crosstalk coefficients • PFISgeom orientation of CCD's in mosaic • PFISdistortion correct pincushion distortion of collimator (r ~ R + AR3 + BR5) • PFISfilters. filter list with pointers to transmission curves in /filters • PFISgratings. grating list with alignment calibration • /masks. mask definition files • /linelists. linelists for calibration lamps: Xe, Ne, HgAr Ast 920 Meeting 7