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Re: DS20 aid needed
Tom wrote:
> As you know, the dark files are incorrectly labeled "bias" in the fits
> headers. How can I do a global edit on a directory of .fits files to
> change the "bias" to "dark"? (If worst comes to worst, I will just go take
> a new set of darks, but it seems like it will be useful to know how to do
> this
Others have given Tom advice on this issue: how to change the
values of keywords in FITS file headers.
Let me point out that I designed my pipeline, in part, so that this
would NOT be necessary. Let me explain. One of the first steps in the
pipeline is to look at all the FITS files in a directory, and read
some information from the header of each one. That information is
then written into a simple ASCII text file, with one line per image.
Each entry looks something like this:
hira2011797.fits I 2452012.79786 100.3 object 204.5 0.0
The fifth word in the line denotes the type of the image: "object",
or "dark", or "flat," or something else.
The default name of this summary of the night's image is "make_list.out",
but one can modify the name in one of the parameter files read by
the pipeline.
Now, one can use an ordinary text editor to modify this file after
it has been created. One could change all occurences of "object"
to "dark", or one particular image from "dark" to "bias", or whatever
one would like.
When one runs subsequent stages of the pipeline, it will read
this ASCII text file to determine the characteristics of each image --
NOT the FITS headers! So changing this summary file (which is easy)
takes the place of changing all the FITS headers (which is hard).
I usually run the pipeline on data several stages at a time,
look at the result, make minor changes if necessary, and then run
the next few stages.
A future version of the pipeline will write additional information
to this summary ASCII file (such as FWHM of each image, number of objects
found, sky value, etc.).
Michael Richmond