Central Bureau for Astronomical Telegrams
IAUC 3068: Poss. Occns BY URANIAN RINGS
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Circular No. 3068
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK Telex: 921428
Telephone: (617) 864-5758
POSSIBLE OCCULTATIONS BY URANIAN RINGS
R. E. McCrosky, Center for Astrophysics, has pointed out that
two stars of magnitude 11-12 come close to being occulted by the
Uranian rings at the end of May. A. R. Klemola, Lick Observatory,
has measured the accurate positions of the stars on a recent plate
taken with the 51-cm double astrograph, and he confirms that no
other stars of magnitude ~ 14 or brighter will be within some 10"
of the center of Uranus during the next three months. These positions
have mean errors of perhaps +/- 0".2 and were reduced to the FK4
system with the help of 34 SRS positions (kindly telexed by L.
Kohoutek, Hamburg Observatory) from the new Perth 70 star catalogue.
The indicated near-occultation times, star positions, and also
approximate magnitudes and spectral types (the latter derived by
C.-Y. Shao from the Palomar Sky Survey prints) are as follows:
1977 UT Star R.A. (1950) Decl. Mag. Sp.
May 29.99 AC 1420-13:127 14 23 52.79 -13 48 36.4 12 A
31.27 AC 1420-13:123 14 23 42.42 -13 47 46.5 11.5 F
Computations by B. G. Marsden suggest that the stars, which have
their closest approaches to Uranus in p.a. 18o, will not be occulted
by the epsilon ring (radius 4".0); but as J. L. Elliot, Cornell University,
has pointed out, there could be as yet undetected rings up to ~ 5"
from Uranus. Local circumstances for the minimum separations are:
Location UT Sep. UT Sep.
Sutherland May 29d23h48m 5"6 - -
Herstmonceux 29 23 52 6.2 - -
La Plata 29 23 53 5.5 May 31d06h35m 5"8
La Serena 29 23 54 5.5 31 06 35 5.9
Tucson - - 31 06 39 6.3
Wellington - - 31 06 41 5.6
South Pole 29 23 50 5.3 31 06 38 5.5
Y. Kozai, Tokyo Astronomical Observatory, has communicated a
photometric tracing recorded by K. Tomita at the Dodaira Station
during the period of ring occultations of SAO 158687 on Mar. 10.
Unfortunately, the epsilon occultation seems to have occurred during a
0.8-min interruption to observe the sky background.
M. K. V. Bappu writes that the times of the Kavalur observations
(IAUC 3061; IAUC 3051 for epsilon) should be changed by -3s.
1977 April 29 (3068) Brian G. Marsden
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