## Quick and Not So Dirty Kast Reduction ##

May 18, 2002 (De Vries, Whalen, Reuland and Dawson)

0. Rename the *.ccd files to *.fits
   rename *.ccd fits field=extn

1. Master bias
   R: Rbias.list
   B: Bbias.list

  cl> imstat @Rbias.list
  #               IMAGE      NPIX      MEAN    STDDEV       MIN       MAX
                   r208    216000     6.682     46.38       -4.     1610.
                   r210    216000     6.646     46.33       -4.     1611.

  cl> imcombine @Rbias.list Rbias.fits comb=average scale=none
      Output image = Rbias.fits, ncombine = 15

  cl> imstat @Bbias.list                                          
  #               IMAGE      NPIX      MEAN    STDDEV       MIN       MAX
                   b207    216000     1.589      51.6      -13.     3098.
                   b209    216000     1.529     51.54      -12.     2882.
  cl> imcombine @Bbias.list Bbias.fits comb=average scale=none

2. Subtract bias
   cl> imarith @rn1_all.list - Rbias @rn1_all.list//b
   cl> imarith @bn1_all.list - Bbias @bn1_all.list//b
   
3. Trim Images (last bias column, and stuff 
   cl> imcopy @rn1_all.list//b[1:1190,10:169] @rn1_all.list//bt
   cl> imdel  @rn1_al.l.list//b ver-
   cl> imcopy @bn1_all.list//b[1:1190,10:169] @bn1_all.list//bt
   cl> imdel  @bn1_all.list//b ver-

4. Make flats
   Ideally, use flat taken immediately after science frames to correct
   for flexure and stuff.
   Median scaled as they have different exposure times
   cl> imcombine @Rdflat.list Rdflat comb=average scale=median 
reject=minmax nlow=3 nhigh=3
   Output image = Rdflat, ncombine = 22
   cl> imcombine @Bdflat.list Bdflat comb=average scale=median 
reject=minmax nlow=3 nhigh=3
   Output image = Bdflat, ncombine = 15

   Construct response function using flats

   response Rdflat Rdflat Rdflat_resp interac=yes
   response Bdflat Bdflat Bdflat_resp interac=yes

   imarith @rn1_all.list//bt / Rdflat_resp @rn1_all.list//btf
   
5. Szap without restoring background  
   (ie cosmic ray zap & background subtraction in one go!)

   Set background parameters:

   cl> epar background
       axis=2
       sample = "5:45,100:108,125:158"
       function=chebyshev
       order = 5

   cl> szap r163btf r163btfzs inter=yes restore=no
   Interactive mode because of shifting spectra....


6. Pairwise subtract
   cl> imarith r161btfzs - r163btfzs r161m163btfzs

7. Apall using b, w, a, s, z
   cl> apall r161m163btfzs

8. Rolling!!
   splot r161m163btfzs.ms