Calculates the topocentric radial velocity of
an observer in a given direction (equatorial
coordinates) and observer's latitude and longitude,
and UTC time.
May be useful for determining observational
frequencies or correcting observation velocities
for cosmic spectral lines - e.g., HI emissions
and masers (but not pulsars).
See instructions and
Instructions: Enter the target
equatorial coordinates (RA/DEC) and
manually enter Latitude and Longitude (in decimal format. (default F4KLO)).
Time (UTC) can be set by the 'UTC Now' button
or entered manually in the format of DD/MM/YYYY
hh:mm:ss (observe format exactly).
Use of the Calculated Radial Velocity: The radial velocity calculated
here is the observer's topocentric velocity
towards the specified direction referenced to the
LSR (local standard of rest). However, in
most cases the spectral line source (e.g. W3)
has its own velocity w.r.t. the LSR, and so
the observed velocity will
be different to that calculated above.
As the observed velocity will
be different for each observatory and varies
over the day and year, in order to compare results
between observatories and over time, a common
VLSR reference is assigned to the source signal.
Use the calculators below to find a VLSR, or
an expected observation frequency.
First, the Spectral Line of interest needs to