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Basic Information on cotra
Task: cotra
Purpose: Coordinate transformations
Categories: utility
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
Key: radec
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.
Key: type
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
B1950 frames.
Key: epoch
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.
Key: uvw
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
uvw=10.0,5.2,7.2
Default: 9,12,7
Key: theta0
LSR speed in km/s. Default: 220
The GSR motion (-62,40,-35) is currently hardcoded.
Key: z
Redshift. You can also give an explicit velocity
defined via the optical or radio definiton
if a 2nd argument is specified, e.g.
z=1234.5,opt
Default : 0
Key: restfreq
Rest frequency of a spectral line in GHz.
Default: 115.271204 (the CO 0-1 transition)