- Form: WSCALE dest [ORD=n] [TTY] [INT] [redirection]
-
- dest
- selects the spectrum for which the wavelength scale is to apply,
- ORD=
- determines the order of the polynomial
expressing the relation between channel number and wavelength,
- TTY
- sends more extensive output to the terminal,
- INT
- allows interactive selection of lines. INT implies TTY.
WSCALE calculates the wavelength calibration polynomial using the
wavelengths and line centers of the calibration spectrum lines identified
by the LINEID command. The resulting calibration is associated with the
spectrum specified by 'dest'. The line centers determined with the LINEID
command are fit to a polynomial of order specified by 'ORD=n'. If the
keyword 'INT' is specified, interactive line weighting can be done. The
program will ask for all unspecified parameters.
The resulting wavelength scale becomes associated with the 'dest'
spectrum. You can then use the COPW command to associate the wavelength
scale with any other spectrum you wish.
Also, note that it is the REVERSE fit which is actually used by the command
ALIGN to linearize a spectrum (see below).
Examples:
- WSCALE 4 ORD=2
- Computes the wavelength scale for spectrum
4, doing a second-order fit to wavelength versus channel number. The
resulting wavelength scale is printed on the terminal.
- WSCALE 4 ORD=2 >fit.txt:
- Does the same as example 1, but
this time sending the output to the file fit.txt in the
current working directory.
- WSCALE 4 ORD=1 INT
- Does a first order fit to wavelength
versus channel number for spectrum 4. The user can interactively
give weights to the identified lines being fit (0 weight discards a
line).