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Basic Information on cotra
Purpose: coordinate transformations
COTRA is a MIRIAD task to transform between astronomical coordinate
systems. The coordinate systems must be one of:
equatorial, galactic, ecliptic, super-galactic
For given galactic longitude,latitude, it also shows three conversions
for common velocity frames of reference:
dVlsr = Vlsr - Vbsr (BSR = Heliocentric)
dVgsr = Vgsr - Vlsr
dVlgsr = Vlgsr - Vgsr
In addition, several conversions between doppler velocities
can be calculated (optical, radio, relativistic)
Input RA/DEC or longitude/latitude. RA is given in hours
(or hh:mm:ss), whereas all the others are given in degrees
(or dd:mm:ss). There is no default.
Input coordinate system. Possible values are
"b1950" (the default), "j2000", "galactic", "ecliptic"
and "super-galactic". b1950 and j2000 are equatorial coordinates
in the B1950 and J2000 frames. All other coordinates are in the
Epoch (in standard Miriad time format) of the coordinate. Note
that this is distinct from the equinox of the coordinate as given
above. Varying epoch changes the coordinate values by less than an
arcsecond. The default is b1950.
Standard Solar motion in right handed UVW coordinate system.
The classic value of 20 km/s toward RA,DEC=18h,30d corresponds to
uvw=10.3,15.3,7.7 but is using too high a value
for V. A bettter, Hipparchos based, value would be
LSR speed in km/s. Default: 220
The GSR motion (-62,40,-35) is currently hardcoded.
Redshift (unitless) or velocity (km/s).
If velocity is given, the optical or radio definition
in a 2nd argument needs to be specified. Valid are
'o' (optical), 'r' (radio) and 'x' (relativistic).
Default : 0
Rest frequency of a spectral line in GHz.
Default: 115.271204 (the CO 0-1 transition)
Generated by email@example.com on 07 Aug 2012