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velfit - fit rotation curve to coplanar disk (WWB73 method)
velfit
[parameter=value]
VELFIT fits a theoretical velocity pattern
to an isovelocity image, weighted by the intensity image and a geometric
factor specified by model input paramaters. The default option is to fit
a rotation curve to an isovelocity image of a rotating disk. The rotation
curve and rms for the fit are printed out and can be used to find the best
fit to the other parameters. For more details see Warner, Wright and Baldwin
(1973MNRAS.163..163W).
Optionally an output map can be generated with amusing
quantities.
The following parameters are recognized in any order
if the keyword is also given:
- in=
- input velocity field, in image(5NEMO)
format. No default.
- radii=
- radii of the ring boundaries. For N rings, N+1
values need to be give. They need to be sorted by increasing radius.
- pa=
- position angle of disk, in degrees. [0]
- inc=
- inclination angle of disk,
in degrees [45]
- center=
- rotation center (mapcenter if left blank, 0,0=lower
left)
- vsys=
- systemic velocity [0]
- den=
- input density image, used to
weigh the velocities. If missing, weights are uniform (but see coswt= below).
Default: none.
- frang=
- free angle around minor axis (2*frang is the total
angle around the minor axis used). [Default: 0]
- blank=
- Value of the blank
pixel to be ignored. Default: 0.0
- coswt=
- power of cos(theta) weighting [1]
- wwb73=
- use the classic WWB73 method. Currently there is no other method.
[t] out= Optional output file. If selected, it will contain the nominal
rotation speed as derived from the local radial velocity in the disk, appropriately
corrected for the geometric factors. Default: none.
rotcur(1NEMO)
,
rotcurshape(1NEMO)
Mel Wright (Fortran version), Peter Teuben
(C version)
30-sep-92 new task in miriad MCHW
5-oct-2003 V1.0 : C version in NEMO PJT
22-oct-2005 V1.1 : added out= PJT
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