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./contrib
casaframevel.pro

Last modification date:
Wed Sep 28 13:27:15 2016

casaframevel

function casaframevel(ra, dec, mjd, sitelong, sitelat, siteelev, fromframe, toframe)

Uses CASA library call to return the velocity of toframe relative to fromframe.

See dcfixvframe or fixvframe for the procedures intended for users to use. This function is primarily for use internal to those procedures. Note that the first time this function is called there will be a small delay while the shared library is loaded. Subsequent calls will be substantially faster.

This calls a function in a shared library that in turn invokes the necessary calls in the CASA library to calculate the relative frame velocities for the given pointing direction, site location, and modified Julian date (mjd). This function is only available in Green Bank and Charlottesville on linux machines because of the nature of the CASA library calls (this does not use pure IDL). This is an interrum solution while a more permanent solution for use more transparently in GBTIDL is researched and implemented.

Contributed By: Bob Garwood, NRAO-CV

Returns
The velocity in m/s of fromframe relative to toframe.
Examples
Given a data container, dc, this gets the casa-calculated frame velocity using the header values in that data container. 
 radec = getradec(dc,2000.0,/quiet)
 ok = decode_veldef(dc.velocity_definition, veldef, velframe)
 vframe = casaframevel(radec[0],radec[1],dc.mjd,dc.site_location[0], $
                       dc.site_location[1], dc.site_location[2], $
                       dc.frequency_type, velframe)
Uses
casaframetrans
Version
$Id$

Parameters
ra
in, required
double 		The J2000 RA in degrees.
dec
in, required
double 		The J2000 Dec in degrees.
mjd
in, required
double 		The modified Julian date in days.
sitelong
in, required
double 		The site (telescope) longitude in degrees east.
sitelat
in, required
double 		The site (telescope) latitude in degrees.
siteelev
in, required
double 		The site (telescope) elevation in meters above sea level.
fromframe
in, required
string 		The "from" reference frame. Must be one of LSRD, LSRK, BARY, GEO, TOPO, GALACTO, LGROUP, and CMB. Usually this will be "TOPO" The returned value is the velocity of toframe relative to this frame.
toframe
in, required
string 		The "to" reference frame. Must be one of LSRD, LSRK, BARY, GEO, TOPO, GALACTO, LGROUP, and CMB. The returned velocity is the velocity of this frame relative to fromframe.

Produced by IDLdoc 1.6 on Wed Sep 28 13:27:47 2016