The COSMOS software does not do
everything, and may very well not do the things it does the way you
would like. If you would like to customize the processing, a good
starting place would be with the output of adjust-map.
The mapfile produced by adjust-map
provides all the information you need to extract the spectral data,
using any method you may chose. The information necessary to locate
any wavelength and slit position is given as a set of
polynomials.
The mapfile has the following
format:
Xdispersion = dirflat
Fit
orders = ord_disp ord_sag ord_tilt ord_sagit ord_len
Scale
~ telscale
Lambda =
lamin lamax
SLIT slitnum
objectname
LENGTH = slitlength
CHIP
chipnum slmax slmin lammin lammax nfint
dispersion
polymonial
inverse-dispersionn polynomial
sag
polynomial
tilt polynomial
sagitta
polynomial
slit-length polynomial
CHIP
chipnum slmin slmax lammin lammax nfint
.
.
.
SLIT
slitnum objectname
.
.
.
END
The
first 4 lines give general parameters:
Xdispersion =
dirflat
.dirflat = 1 if the dispersion is along the x direction of the chips (i.e. along the rows), otherwise dirflat = 0.
Fit orders = ord_disp ord_sag ord_tilt ord_sagit
ord_len
|
ord_disp |
order of the dispersion fit, and the inverse dispersion fit |
|
ord_sag |
order of the spectrum "sag" fit |
|
ord_tilt |
order of the spectrum tilt fit |
|
ord_sagitta |
order of the slit curvature fit |
|
ord_len |
order of the slit length fit |
Scale ~
telscale.
.Image scale at ccd focal plane. (Hard-wired into map-spectra.)
Lambda =
lamin lamax
.minimum and maximum wavelengths of spectrum fits in this file
For each slit, there
is a line:
SLIT slitnum objectname
.slitnum is the sequence number, and objectname the name given in the SMF file
Only well-behaved
slits have the following data. A well--behaved slit is one in which
both ends of the slit fall onto the same chip (the spectrum may well
span several slits in the dispersion direction).
LENGTH =
slitlength
.slitlength is the nominal length of the slit, in pixels
for each chip that
the spectrum traverses, the following data is given:
CHIP chipnum slmax slmin lammin lammax nfint
|
chipnum |
chip number |
|
slmin |
distance to "left" end of slit from object, in pixels |
|
slmax |
distance to "right" end of slit from object, in pixels |
|
lammin |
minimum wavelength of spectrum on this chip |
|
lammax |
maximum wavelength of spectrum on this chip |
|
nfint |
an almost useless number; ingore |
fit of lambda vs pixel coordinate in the
dispersion direction and the inverse fit of pixel
coordinate vs lambda
fit of pixel
coordinate of the object perpendicular to the dispersion direction
(i.e. along the
slit. Note that this is
equal to the slit center only if the mask design places the object
midway along the
slit.