COMB-Corrects for S-distortion using continua

Description:

This is a program to correct data for s-distortion by moving data in the cross-section direction to line it up for a comb of continua spectra.This correction is then applied to the data itself. A comb dekker is used to produce about ten continuum spectra across an image (this is done at the telescope). This image is then used by the program:- The program requests two adjacent "teeth" to be marked, it locates the remaining teeth and follows them along the image (in the channel direction), finding the line centres by fitting gaussians. The points so obtained are fitted with Chebyshev polynomials (for each tooth), The intermediate positions are interpolated from these, which are then used to evaluate the required movement for each data point. The coefficients are written to a file which may then be read by the program to apply correction to the actual data. Alternatively if QUICK is specified centriods are used rather than Gaussians.

Parameters:

IMAGE

IMAGE = FILE (Read) Name of image for input This should be a file containing continua spectra.

ARC_OPTS

ARC_OPTS = CHARACTER (Read) Enter arc fit option NEW : set up a new wavelength calibration REPEAT : Itterate on previous calibration. CLONE : CLone a previous calibration. OLD : Correct using previous results

OUTPUT

OUTPUT = FILE (Write) Name of output file File to contain corrected data.

XSTART

XSTART = INTEGER (Read) analysis lower limit The data between the limits xstart and xend is extracted and the resultant spectrum is used to locate the lines.

XEND

XEND = INTEGER (Read) analysis upper limit The data between the limits xstart and xend is extracted and the resultant spectrum is used to locate the lines.

XBLOCK

XBLOCK = INTEGER (Read) Enter averaging width in channels Each window is of this width (except perhaphs the final one).

ITERATION

ITERATION = INTEGER*2 (Read) New value of iteration

LEVEL

LEVEL = REAL (Read) Level of edge of tooth

ORDER

ORDER = INTEGER (Read) order for polynomial fitting This is for the continuity correction of the data. Idealy the arc should have been pre-processed with ARCSDI, so a low order e.g. 2 should be used.

MAXLINES

MAXLINES = INTEGER (Read) Maximum number of lines to allow room for This must be greater than or equal to the number of lines fitted, so room should be allowed in case any more are to be added later.

CLFILE

CLFILE = FILE (Read) Name of image for cloning from This should be a file containing an arc spectrum.

TOLS

TOLS = CHARACTER (Read) For use in batch only

KEEP_ITT

KEEP_ITT = LOGICAL (Read) keep itteration files?

QUICK

QUICK = LOGICAL (Read) Centriod rather than fit gaussians?

PRFITS

PRFITS = LOGICAL (Read) Print out details of fitting

PLOTCORR

PLOTCORR = LOGICAL (Read) Plot correction?

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