AIPS HELP file for AXVAL in 31DEC18
As of Thu Apr 26 16:39:14 2018
Type: Adverb (array(2))
Use: To specify the value of the coordinate at the reference
pixel on a specified axis. FITS standard units are mks
with degrees and Jy added. AXVAL is an array to allow
greater precision in the specified value. The axis
value is taken to be AXVAL(1) + AXVAL(2) with both
values converted to double precision before adding. For
example, the frequency 1.420405752E6 is too precise for
a single adverb. However, AXVAL = 1.4204E6, 5752. will
convey the desired value correctly. NOTE, if AXVAL(1)
= AXVAL(2), then the axis value is taken to be just
Null value: none
AXDEFINE...Define new axis or alter previous axis description.
AXVAL must be specified.
ALTDEF.....Define an alternate description in velocity units
of a frequency axis. AXVAL is the reference pixel
velocity in meters/sec.