SLA_ETRMS

E-terms of Aberration

ACTION:
Compute the E-terms vector – the part of the annual aberration which arises from the eccentricity of the Earth’s orbit.
CALL:
CALL sla_ETRMS (EP, EV)
GIVEN:
 EP D Besselian epoch

RETURNED:
 EV D(3) E-terms as $\left[\Delta x,\Delta y,\Delta z\phantom{\rule{0.3em}{0ex}}\right]$

NOTE:
Note the use of the J2000 aberration constant (′′2049552). This is a reflection of the fact that the E-terms embodied in existing star catalogues were computed from a variety of aberration constants. Rather than adopting one of the old constants the latest value is used here.
REFERENCES:
(1)
Smith, C.A. et al., 1989. Astr.J. 97, 265.
(2)
Yallop, B.D. et al., 1989. Astr.J. 97, 274.