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 Besselian epoch

RETURNED:

$$[\Delta x, \Delta y, \Delta z\,]$$ EV

NOTE:

Note the use of the J2000 aberration constant ( $20\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.49552$ ). 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.