Note: there are two different kinds of arcs, ones for N&S, and standard arcs. Check the MASKNAME in the PHU to check which type it is and be sure to use the correct type with the data.

Prepare arc with GSREDUCE

- GSREDUCE ga*

      inimages = "ga*"           Input GMOS images or list
      (outimages = "")	         Output images or list
      (outpref = "gs")	         Prefix for output images
     *(fl_over = no)             Subtract overscan level
     *(fl_trim = yes)            Trim off the overscan section
     *(fl_bias = yes)            Subtract bias image
      (fl_gscrrej = no)          Clean images for cosmic rays
      (fl_dark = no)             Subtract (scaled) dark image
     *(fl_flat = no)             Apply flat field correction
     *(fl_gmosaic = yes)         Mosaic science extensions
     *(fl_fixpix = no)           Interpolate across chip gaps if mosaicing
     *(fl_gsappwave = yes)       Run gsappwave on reduced image
     *(fl_cut = yes)             Cut slits into separate spectra if mosaicing
      (fl_title = yes)           Put object id in title of cut spectra (MOS only)
      (fl_vardq = no)            Create variance and data quality frames
     *(bias = "bias.fits")       Bias image name

==> gsreduce fl_over- fl_trim+ fl_bias+ fl_gmos+ fl_gsap+ fl_cut+

- GSWAVELENGTH both arcs seperately

- bad lines: 6057.5, 6298, 6306.65, 6368, 6482.27, 7313, 7352.9
6058.7, 6307, 6368, 6482, 7313, 7352.9, 6298?

- Gemini South: bad lines = 6033, 6058, 6113, 6367, 6482, 7313, 7385

It may be a good idea to print wavelength calibration lines and trace for future reference.

=> 2 gsga (with two central wavelengths)
cleanup: mv ga* proc_images/