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Precessional Constant Determined from Optical Astrometry

Published online by Cambridge University Press:  30 March 2016

M. Miyamoto*
Affiliation:
National Astronomical Observatory, Mitaka, Tokyo 181, Japan

Extract

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We have analyzed proper motions of about 30000 K-M giants chosen from the astrometrie catalogue ACRS Part 1 (Corbin and Urban 1991). To avoid localized velocity fields, these K-M giants are chosen from the heliocentric distance interval 0.5 - 1.0 kpc. Starting from the initial trial of the luni-solar precessional correction Δρ ~ —0”.3/cy, we have found that the motion of stars are well expressed in terms of the Oort constants for the K-M giants. After confirming that the K-M giants are in a steady-state, we have applied the velocity-field model of the plane-parallel galactic rotation with non-zero Oort constants. Then, we have found a rational set of the corrections to the FK5 system: Δρ = -0”.27 ± 0”.03/cy and Δe + Δλ = —0”.12 ± 0”.03/cy, as is shown in Table 1 (Miyamoto and Sóma 1993). In consequence, the FK5 system is still rotating.

Type
II. Joint Discussions
Copyright
Copyright © Kluwer 1995

References

Corbin, T.E. and Urban, S.E. (1991) Astrographic Catalogue Reference Stars (ACRS), U.S. Naval Observatory.Google Scholar
Miyamoto, M. and Sòma, M. (1993) AJ, 105, 691. L9.CrossRefGoogle Scholar