coefs -- Extract dispersion coefs from mtn HeNeAr headers
coefs input records database
- The input image root name for the spectral images containing the dispersion coefficients.
- The range of records for which the root name applies.
- The database file name which will contain the coefficients.
The spectra specified by the combination of the root name and the records are scanned for the presence of dispersion coefficients. If present, the coefficients and necessary information are written to the file indicated by the database parameter. This file an then be used by the linearization program DISPCOR to correct any spectra for which the database is appropriate.
Each invocation of COEFS appends to the database file, or creates a new file if necessary.
The following assumptions are made concerning the coefficients, which are always correct for IIDS and IRS mountain reduced data at Kitt Peak.
- The coefficients represent Legendre polynomials.
- The coefficients apply to pixels 1 through 1024 in the original data.
The following example reads the coefficients from the headers for nite1 arc spectra taken near the beginning and end of the night and creates a database file called nite1.db:
cl> coefs nite1 3-4,201-202 nite1.db
Approximately 1 second per spectrum is required. This is primarily overhead due to file access.