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Hi,I'm trying to use the IRAF task "response" (in noao.twodspec.longslit),
but I'm confused about its output. When I run it on a flatfield, I end up
with a "response calibration image", but that image looks like it's been
processed, not like something I should be using to calibrate other images.
It also seems to melike there should be a way to find/use the parameters
from the interactive fitting, but I can't find them anywhere in the FITS
header of the image. According to the help file,"When the task finishes creating a response image the fitting
parameters are updated in the parameter file." Does this mean the parameter file for response in the uparm directory, or
something else? Thanks for your help-Alex----------------------------------------
Alexandria Ware
Department of Physics, UC Santa Barbara
aware@xmmom.physics.ucsb.edu
http://xmmom.physics.ucsb.edu/~aware/
----------------------------------------

Good Afternoon, I am not sure what you mean by
...When I run it on a flatfield, I end up with a "response calibration
image", but that image looks like it's been processed, not like something
I should be using to calibrate other images... The 'response' task removes the shape of the flat field lamp source from
the flat field. It does this by removing a uniform (fit to an average flat
field spectrum) function from every point across the dispersion. Because it
divides each line/column of the 2D flat field by the average flat field
spectrum the values across the slit direction are not necessarily 1, only the
average is 1. In other words, the slit response is still present in
the flat. Is this what you are seeing in your output image? With regard to the interactive fitting, as you note the task says "When the task finishes creating a response image the fitting
parameters are updated in the parameter file." Indeed, this means the values of the 'response' parameter file have been
updated to the values used by the task. In effect, the file in the UPARM
directory has been updated, but you do not (and really should not) use this
file. If you simply do an cl> lpar response after the task has been run, you will see the values have been updated.
These values can then be used in your interactive session or by a CL script
you have written. Information regarding to the fitting process is not
written to the header of the output file. Best,
Michele De La Peña