SLA_SUBET

Remove E-terms

ACTION:
Remove the E-terms (elliptic component of annual aberration) from a pre IAU 1976 catalogue [α, δ] to give a mean place.
CALL:
CALL sla_SUBET (RC, DC, EQ, RM, DM)
GIVEN:

RC,DC

D

[α, δ] with E-terms included (radians)

EQ

D

Besselian epoch of mean equator and equinox


RETURNED:

RM,DM

D

[α, δ] without E-terms (radians)


NOTE:
Most star positions from pre-1984 optical catalogues (or obtained by astrometry with respect to such stars) have the E-terms built-in. This routine converts such a position to a formal mean place (allowing, for example, comparison with a pulsar timing position).
REFERENCE:
Explanatory Supplement to the Astronomical Ephemeris, section 2D, page 48.