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SLA_SUBET - Remove E-terms   

ACTION:
Remove the E-terms (elliptic component of annual aberration) from a pre IAU 1976 catalogue $[\,\alpha,\delta\,]$ to give a mean place.

CALL:
CALL sla_SUBET (RC, DC, EQ, RM, DM)

GIVEN:

RC,DC D $[\,\alpha,\delta\,]$ with E-terms included (radians)
EQ D Besselian epoch of mean equator and equinox

RETURNED:

RM,DM D $[\,\alpha,\delta\,]$ 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.


next up previous
Next: SLA_SUPGAL - Supergalactic to Galactic
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Previous: SLA_SMAT - Solve Simultaneous Equations

SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk