Compare sets of calibration images.

[sco@mcs t2]$ caldif /hetdata/20160430/virus/virus0000105/exp10/virus /hetdata/20160423/virus/virus0000105/exp10/virus 
Set1:  virus zro ___ List.1   Number=36
Set2:  virus zro ___ List.2   Number=36
20160430T025800.7_074LL_zro_DIF.fits 64513.4648 0.0505 15.9606 100000
20160430T025800.7_074LU_zro_DIF.fits 64526.9492 0.1433 45.3217 100000
20160430T025800.7_074RL_zro_DIF.fits 54662.5195 10.8522 3431.7588 100000
20160430T025800.7_074RU_zro_DIF.fits 9043.1133 0.8864 280.3046 100000
20160430T025800.7_075LL_zro_DIF.fits 8.1122 0.0154 4.8811 100000
20160430T025800.7_075LU_zro_DIF.fits 7.6272 0.0245 7.7631 100000
20160430T025800.7_075RL_zro_DIF.fits 26.5568 0.0280 8.8624 100000
20160430T025800.7_075RU_zro_DIF.fits 11.9718 0.0297 9.3847 100000
20160430T025800.7_084LL_zro_DIF.fits 1.8068 0.0412 13.0152 100000
20160430T025800.7_084LU_zro_DIF.fits 5.4363 0.0208 6.5927 100000
20160430T025800.7_084RL_zro_DIF.fits 8.3392 0.0189 5.9850 100000
20160430T025800.7_084RU_zro_DIF.fits 8.0085 0.0307 9.6926 100000
20160430T025800.7_085LL_zro_DIF.fits 15.2601 0.0157 4.9741 100000
20160430T025800.7_085LU_zro_DIF.fits 14.4878 0.0157 4.9630 100000
20160430T025800.7_085RL_zro_DIF.fits 10.0773 0.0173 5.4787 100000
20160430T025800.7_085RU_zro_DIF.fits 12.6734 0.0267 8.4381 100000
20160430T025800.7_094LL_zro_DIF.fits 16.9539 0.1213 38.3489 100000
20160430T025800.7_094LU_zro_DIF.fits 20.8253 0.0250 7.8924 100000
20160430T025800.7_094RL_zro_DIF.fits 140.5905 0.0362 11.4528 100000
20160430T025800.7_094RU_zro_DIF.fits 14.1892 0.0165 5.2239 100000
20160430T025800.7_095LL_zro_DIF.fits 10.3732 0.0182 5.7571 100000
20160430T025800.7_095LU_zro_DIF.fits 12.5232 0.0175 5.5418 100000
20160430T025800.7_095RL_zro_DIF.fits 11.2863 0.0285 9.0153 100000
20160430T025800.7_095RU_zro_DIF.fits 4.1890 0.0369 11.6710 100000
20160430T025800.7_103LL_zro_DIF.fits 12.8352 0.0204 6.4468 100000
20160430T025800.7_103LU_zro_DIF.fits 10.2250 0.0307 9.7147 100000
20160430T025800.7_103RL_zro_DIF.fits 9.0599 0.0162 5.1089 100000
20160430T025800.7_103RU_zro_DIF.fits 6.6234 0.0157 4.9576 100000
20160430T025800.7_104LL_zro_DIF.fits 4.6717 0.0163 5.1406 100000
20160430T025800.7_104LU_zro_DIF.fits 3.7650 0.0415 13.1346 100000
20160430T025800.7_104RL_zro_DIF.fits 5.8117 0.0217 6.8484 100000
20160430T025800.7_104RU_zro_DIF.fits 5.2871 0.0492 15.5524 100000
20160430T025800.7_105LL_zro_DIF.fits 9.9786 0.0149 4.7093 100000
20160430T025800.7_105LU_zro_DIF.fits 12.1705 0.0172 5.4438 100000
20160430T025800.7_105RL_zro_DIF.fits 7.9519 0.0148 4.6822 100000
20160430T025800.7_105RU_zro_DIF.fits 6.9143 0.0167 5.2760 100000
  
To view the difference images: 
ds9 -geometry 1000x800 -zscale -zoom 0.35 *.fits

Other notes: 

# Typical data structures for VIRUS:
# virus0000105/exp10/  zro   bias
# virus0000104/exp10/  drk   dark
# virus0000103/exp05/  flt   flat (ldls)
# virus0000102/exp05/  cmp   comparison arc (Cd)
# virus0000101/exp05/  cmp   comparison arc (Hg)

# Typical data structures for LRS2:
#  /hetdata/20160429/lrs2/lrs20000101/exp10/lrs2   cmp       Hg
#  /hetdata/20160501/lrs2/lrs20000202/exp10/lrs2   cmp       Cd
#  /hetdata/20160501/lrs2/lrs20000203/exp10/lrs2   flt       Qth
#  /hetdata/20160501/lrs2/lrs20000204/exp10/lrs2   flt       ldls
#  /hetdata/20160501/lrs2/lrs20000205/exp10/lrs2   drk       ___
#  /hetdata/20160501/lrs2/lrs20000206/exp10/lrs2   zro       ___

To compare virus sets:

bias:
/hetdata/20160430/virus/virus0000105/exp10/virus
/hetdata/20160423/virus/virus0000105/exp10/virus
So, I would use:

% caldif /hetdata/20160430/virus/virus0000105/exp10/virus /hetdata/20160423/virus/virus0000105/exp10/virus
darks:
/hetdata/20160430/virus/virus0000104/exp10/virus
/hetdata/20160423/virus/virus0000104/exp10/virus