Program: CONREMCHEB
Purpose: Removes continuum from channel maps by fitting a
polynomial or a Chebychev series to the continuum channels.
Category: ANALYSIS, COMBINATION
File: conrem.py
Author: M.G.R. Vogelaar
Keywords:
INSET= Set and subsets from which to subtract the continuum:
FITSET= Set and subsets for which to fit the continuum:
Number of profiles with fit data must be equal to number
of input profiles
DEGREE= Degree of pol. or series to be fitted: [1]
Maximum degree depends on the number of available
x values in the fit.
OUTSET= Set and subsets for the result:
The result depends on the value of SUBTRACT=
FUNCTION= Fit standard Polynomial or Chebyshev series? P/[C]
Default is a Chebyshev series.
FITOUTSET= Set to write fit results only: [skip]
Write the fitted continuum to a set. The set is created and
has the same size and header as the input set.
Description: A polynomial or a Chebyshev series of degree NPOLY= is
fitted to the subset selected with FITSET= for each
grid position in the subset separately.
This fitted polynomial can then be subtracted
from the subsets selected with INSET= and/or can be used
to calculate an interpolated continuum in OUTSET=.
The program is especially useful for removing the continuum
from a series of line maps.
Example: CONREMCHEB
CONREM Version 1.0 (Jul 30 1991)
CONREMCHEB INSET=NGC4214 3:58
Set NGC4214 has 3 axes
RA-NCP from -127 to 128
DEC-NCP from -127 to 128
FREQ-OHEL from 1 to 63
CONREMCHEB FITSET=NGC4214 3:16 42:58
Set NGC4214 has 3 axes
RA-NCP from -127 to 128
DEC-NCP from -127 to 128
FREQ-OHEL from 1 to 63
CONREMCHEB DEGREE=1
CONREMCHEB OUTSET=NGC4214_SUB
Set NGC4214_SUB has 3 axes
RA-NCP from -127 to 128
DEC-NCP from -127 to 128
FREQ-OHEL from 3 to 58
CONREMCHEB FUNCTION=P
CONREMCHEB FITOUTSET=fit4214
CONREMCHEB +++ FINISHED +++
Updates: Aug 28, 2013: VOG Document (based on conrem.dc1) created
Note: This program provides functionality as in CONREM but besides a
standard polynomial, you can also fit a Chebychev series, which
is less sensitive to oscillations at the edges of a fit interval
(Runge's phenomenon).
With versions of NumPy >= 1.7.1 the fit functions accepts multiple
profiles to fit. This makes the program (much) faster than versions
with an older NumPy.#<