Central Bureau for Astronomical Telegrams
IAUC 3780: Poss. Occn BY PLUTO ON 1983 Apr. 4; Cyg X-1; OJ 287
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Read IAUC 3781
Circular No. 3780
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
POSSIBLE OCCULTATION BY PLUTO ON 1983 APRIL 4
R. L. Millis and L. H. Wasserman, Lowell Observatory, write:
"On Apr. 4d07h36m UT Pluto will pass very near the ninth-magnitude
star BD +6 2851 (R.A. = 14h09m11s, Dec;/ = +5deg37'3, equinox 1950.0).
From positions of Pluto and the star on a recent 0.5-m double-
astrograph plate taken and measured by A. R. Klemola at the Lick
Observatory, we derive a minimum geocentric separation of the two
objects of 0".4. This implies that Pluto's shadow will miss the
earth's northern limb by ~ 500 km. However, the uncertainty is
such that an actual occultation might occur in the general area of
the Americas, Hawaii and the Caribbean. Since 1978 P1 is predicted
to be near greatest northern elongation at the time, no occultation
by the satellite is expected. This potentially important
appulse was discovered by D. di Cicco, Sky Publishing Corporation.
BD +6 2851 forms a conspicuous triangle with BD +6 2849 and BD
+6 2852. None of these stars is in the AG, Yale or SAO catalogues,
and we point out that, contrary to what is given in the
BD, BD +6 2849 is ~ 1' north of BD +6 2852."
CYGNUS X-1
J. C. Kemp, Physics Department, University of Oregon, reports:
" The finding by Priedhorsky and Terrell (1983, Sky Tel. 65,
221) of a 294-day period in the x-ray periodicity of Cyg X-1 is
confirmed in the 10-year photometric record of the optical
counterpart V1357 Cyg = HDE 226868. My data base in B, comprising
data over 1972-77 (E. N. Walker), 1974-76 (I. G. Nolt) and 1976-83
(Kemp et al.), shows a 294-day Fourier amplitude of 0.05 +/- 0.01
mag, with a probability of nondetection of 2 . 10**-4. The 294-day
peak is the highest in the power spectrum over the range 3-3000
days. The epoch for light minimum is JD 2440289, apparently within
a few days of the x-ray minimum (Priedhorsky and Terrell, Ap.J.
Lett. preprint)."
OJ 287
J. E. Bortle, Stormville, NY, reports that this object (IAUC
3764) is now almost back to minimum. Visual magnitude estimates:
Feb. 15.15 UT, 14.2; 21.06, 14.2.
1983 March 4 (3780) Brian G. Marsden
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