AIPS HELP file for SPECINDX in 31DEC18
As of Sat Jun 23 11:34:33 2018
Type: Adverb (Real)
Use: Spectral index defined so that the flux is proportional to
(frequency) ^ (spectral index)
In full detail:
log(T(f)/T(f0) = S * log(f/f0) + C(1) * (log(f/f0))^2
+ C(2) * (log(f/f0))^3 + C(3) * (log(f/f0))^4
where S is SPECINDEX and C is SPECURVE, f0 is 1 GHz for
simplicity, and all logs are base 10. It is unlikely for you to
have reliable values for SPECURV(3); SETJY uses only through
SPECURVE(2) for the basic flux calibration sources.
BPASS.....Computes spectral bandpass correction table.
SPECINDX is used to remove a slope from the derived
bandpass amplitude spectrum.
SOUSP.....Fits SPECINDX and SPECURVE to the fluxes in an SU table
returning the values for input to BPASS.