GMOS Standard

Review of reduction steps needed on flux standard: (to reduce a standard telluric, see standard GMOS reduction page)

1. Find and prepare flux standard as described in Gemini Getfiles

2. prepare flats: GMOS Flats

3. prepare arcs: GMOS Arcs

4. gsreduce target - see gsreduce.txt

5. gstransform target - gstransform gsgsgtNfilename wavtran=gsgaNfilename

6. gsskysub tgsgsgsgt*

7. gsextract stgsgsgsgt*

8. gsstandard estgsgsgsgt*

- graphs=srei, sens.fits is the calibration spectrum - Note: You may need to add points to constrain wobbles in the fit. Also watch the scatter in error. If it has a pattern, try a higher order.

- Apply flux calibration to flux calibrator - gscalibrate estgsgsgsgt*

GSSTANDARD parameters:

 
input   = estgsgsgsgtS20070914S0117.fits  Input image(s)
sfile   =                  std  Output flux file (used by SENSFUNC)
sfunctio=                 sens  Output root sensitivity function image name
(sci_ext=                  SCI) Name or number of science extension
(key_air=              AIRMASS) Header keyword for airmass
(key_exp=              EXPTIME) Header keyword for exposure time
(fl_inte=                  yes) Run the task interactively
(starnam=                 eg21) Standard star name(s) in calibration list
(samesta=                  yes) Same star in all apertures
(apertur=                     ) Aperture selection list
(beamswi=                   no) Beam switch spectra
(bandwid=                INDEF) Bandpass width
(bandsep=                INDEF) Bandpass separation
(fnuzero=  3.6800000000000E-20) Absolute flux zero point
(caldir =         home$caldir/) Directory containing calibration data
(observa=         Gemini-South) Observatory
(mag    =                     ) Magnitude of stars
(magband=                     ) Magnitude types/bands (U|B|V|R|I|J|H|K|L|Lprime|
(teff   =                     ) Effective temperature of spectral types
(ignorea=                  yes) Ignore apertures and make one sensitivity functi
(extinct=                     ) Extinction file
(out_ext=          extinct.dat) Output revised extinction file
(functio=              spline3) Fitting function
(order  =                    6) Order of fit
(graphs =                 srei) Graphs per frame
(marks  =       plus cross box) Data mark types (marks deleted added)
(colors =              2 1 3 4) Colors (lines marks deleted added)
(verbose=                  yes) Verbose?
(logfile=                     ) Logfile name
(status =                    0) Exit status (0=good)
(scanfil=                     ) For internal use only
(mode   =                   ql)