Equinox - Position and motion during 250 years
Open Access
- 1 September 1977
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 180 (1) , 65P-73P
- https://doi.org/10.1093/mnras/180.1.65p
Abstract
Recent meridian observations of the Sun made at Herstmonceux indicate that the right ascensions of Newcomb’s equatorial fundamental stars require a correction ΔN of + 0S.003, agreeing closely with values obtained from modern occultations. An investigation has been made of the position and motion of the equinox obtained from observations of the Sun from 1755 to 1973. All observed data have been adjusted to a uniform system. Because of a suspected non-linear drift in the plotted points a parabola was fitted by least squares. The final solution from 52 equations of condition gave ΔN = − 0S.0366 ± (0S.0036 + (0S.0064 ± 0S.0063) T + (0S.0439 ± 0S.0135) T2 (s.e.) where T is measured in centuries from 1900. The quadratic term predominates. Straight-line solutions derived by successive investigators fall near to this parabola. The implied acceleration of the equinox along the equator is 1.3 arcsec per century per century.Keywords
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