VLSR Calculator

This routine will calculate the radial velocity of the observer with respect to a given RA and DEC on the date of observation for a number of popular standards of rest.

Year: Month: UT Date:
UT Time (format HHMMSS.SS):
Right Ascension (format HHMMSS.SS):
Declination (format -DDMMSS.S):
Coordinate Equinox (format Eyyyy.yy):
Earth Reference Frame:


The algorithm for calculating VLSR was written by M. A. Gordon and can be found in Methods of Experimental Physics, Volume 12, Part C: Radio Observations , Ed. M. L. Meeks. The B in the epoch field refers to the FK4 system (Besselian), J refers to the FK5 system (Julian). The quoted accuracy is 0.02 km s-1.