- using 1 sigma clipping could cut strong emission lines
   - set w1 and w2 to cut off messy regions.


SCOMBINE

    (group = "apertures")    Grouping option
    (combine = "average")      Type of combine operation
    (reject = "sigclip")      Type of rejection\n
    (first = no)             Use first spectrum for dispersion?
    (w1 = 6100.)          Starting wavelength of output spectra
    (w2 = 10250.)         Ending wavelength of output spectra
    (scale = "none")         Image scaling
    (zero = "none")         Image zero point offset
    (weight = "exposure")     Image weights
    (nkeep = 2)              Minimum to keep (pos) or maximum to reject (neg)
    (mclip = yes)            Use median in sigma clipping algorithms?
    (lsigma = 1.)             Lower sigma clipping factor
    (hsigma = 1.)             Upper sigma clipping factor
    (rdnoise = "0.")           ccdclip: CCD readout noise (electrons)
    (gain = "1.")           ccdclip: CCD gain (electrons/DN)
    (snoise = "0.")           ccdclip: Sensitivity noise (fraction)
    (sigscale = 0.1)            Tolerance for sigma clipping scaling corrections