iraf.net

I am trying to use `scombine' in `echelle' to combine the various
orders of a flux-calibrated MagE spectrum in MS format into a
single 1D spectrum on a linear, equidistant wavelength scale.When I `scombine' the object or sky orders with the following
params:
scombine.combine = "average"
scombine.reject = "none"
the 1D spectrum looks just fine. (I use a script to restrict
the pixel range of each order, so order-boundary effects are
minimized.)However, when I am trying to `scombine' the *sigma* orders, in
admittedly primitive fashion, with the following params:
scombine.combine = "average"
scombine.reject = "minmax"
scombine.nlow = 0
scombine.nhigh = 1
scombine.nkeep = 1
the 1D spectrum looks awful. According to the help file for
`scombine', the above params should make `scombine' always choose
the *lower* value of the two sigma orders where they overlap.
Instead, `scombine' insists on averaging both orders in the
overlap zone.Replacing the "average" of `scombine.combine' with "sum" does not
help. On the contrary, now the sum of both orders is presented
in each overlap zone, which is twice the average.FYI, the overlap zones always contain only 2 orders, never 3.
Hence, `scombine' always faces either one pixel, in which case it
takes it, or 2 pixels in an overlap zone, in which case it takes
both instead of only the lower one under the `reject = "minmax"'
option.Can someone please tell me how I can make `scombine' pick the
lower of two values when two spectra are to be combined?