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sumspec

sumspec combines extracted 1-d or 2-d spectrum files. The output spectra are a straight sum of the input spectra. CR rejection can be applied to 2-d files if there are multiple input files. The output file format is the same as the input format, as described in the documentation for extract-2dspec.

 

USAGE	sumspec -o outfile infiles
INPUT	infiles is a list of input files root names (e.g. ccdnnnn)
OUTPUT	outfile is the name of the new file created. It must end in _1spec or _2spec
PARAMETERS	clean remove cosmic rays? siglimit CR rejection threshold in units of sigma both remove both positive and negative residuals? iterations number of iterations of cleaning grow rejected region grow width, in pixels

 

Details:

Unless cosmic ray rejection is requested, sumspec simply sums the intensity values from each file. If the input files contain a second plane with error data, the error values are combined appropriately. If CR rejection is requested (2-d data only), the data are first scaled by exposure time, then summed and data points more than siglimit higher than the mean given zero weight, after which a final sum is made. CR rejection requires input data produced with newer versions of COSMOS which include the exposure time.

For normal (as opposed to nod&shuffle) data, rejecting only positive deviations (both = 'n') usually works best, and is the only way to CR clean frames when there are only two. Nod&shuffle data must have the shuffled region subtracted before using sumspec, and then requires that both positive and negative deviations be removed, and a minimum of three frames.

If the grow parameter is set to a non-zero value, a border of additional rejected pixels is added to any region of rejected pixels.

The spectrum files to be summed must match identically: data sampling and object list. To ensure this, the extraction of all spectrum files should start with the same initial map file, created with map-spectra. (The final map files will differ slightly, of course, since each will have been modified using adjust-map and a different comparison arc.)

 

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