AIPS HELP file for RESTFREQ in 31DEC18
As of Mon Oct 15 12:13:05 2018
Type: Adverb (array(2))
Use: To specify the spectral-line rest frequency in Hertz. RESTFREQ
is an array to allow greater precision in the specified value.
The rest frequency is taken to be RESTFREQ(1) + RESTFREQ(2) with
both values converted to double precision before adding. For
example, the frequency 1420.405752E6 is too precise for a single
adverb. However, RESTFREQ = 1420.4E6, 5752. will convey the
desired value correctly. NOTE, if RESTFREQ(1) = RESTFREQ(2),
then the rest frequency is taken to be just RESTFREQ(1).
Null value: none
ALTDEF.....Define an alternate description in velocity units
of a frequency axis. RESTFREQ is the line rest
frequency in Hz.