Return the equivalency pairs for the radio convention for velocity.
The radio convention for the relation between velocity and frequency is:
V = c \frac{f_0 - f}{f_0} ; f(V) = f_0 ( 1 - V/c )
Parameters : | rest : Quantity
|
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References
NRAO site defining the conventions
Examples
>>> import astropy.units as u
>>> CO_restfreq = 115.27120*u.GHz # rest frequency of 12 CO 1-0 in GHz
>>> radio_CO_equiv = u.doppler_radio(CO_restfreq)
>>> measured_freq = 115.2832*u.GHz
>>> radio_velocity = measured_freq.to(u.km/u.s, equivalencies=radio_CO_equiv)
>>> radio_velocity
<Quantity -31.2090920889... km / s>