Central Bureau for Astronomical Telegrams
IAUC 4303: 1987d; 1987b; PLUTO
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Read IAUC 4304
Circular No. 4303
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 617-495-7244/7440/7444
COMET TERASAKO (1987d)
H. Kosai, Tokyo Astronomical Observatory, reports the
following observations of a comet discovered by Masanori Terasako:
1987 UT R.A. (1950) Decl. m1 Observer
Jan. 24.396 23 16.3 -30 32 8 Terasako
25.382 23 23.5 -29 55 8 "
26.378 23 31.2 -29 23 8 Mitsuma
26.382 23 29.5 -29 25 8 Shibasaki
M. Terasako (Hamamatsu, Shizuoka). 0.15-m binocular.
S. Mitsuma (Honjo, Saitama). Comet diffuse with condensation.
H. Shibasaki (Tokyo Observatory). Comet diffuse with condensation.
PERIODIC COMET WISEMAN-SKIFF (1987b)
Total visual magnitude estimates: Jan. 22.1 UT, 14.5: (D.
Levy, Tucson, AZ, 0.4-m reflector); 26.43, 13.3 (C. S. Morris,
Pyramid Lake, CA, 0.26-m reflector).
PLUTO
D. J. Tholen, University of Hawaii, reports: "Successful
observations with the 2.24-m telescope on Mauna Kea of the 1986 Dec
29 total occultation of Charon by Pluto show the depth to be about
0.185 mag. The B magnitudes of Pluto and Charon individually were
therefore 14.94 and 16.76, respectively, at that rotational phase.
Using a slope parameter of 0.86, the B absolute magnitudes are
0.10 and 1.93, respectively. Assuming the apparent B magnitude of
the sun to be -26.07, the product of the disk-integrated geometric
albedo and the cross-sectional area is 2.395 x 10**6 km2 for Pluto
and 0.445 x 10**6 km2 for Charon. The time of third contact was
late by about 10 min, implying a larger radius for Pluto and a
smaller radius for Charon than used by Tholen et al. (1987, Astron.
J. 93, 244) to generate the circumstances. A radius of 1210 km
for Pluto yields a blue geometric albedo of 0.52; a radius of 590
km for Charon yields albedo 0.40. An improved value for the mean
density of the system is 1.82 g cm-3. Successful observations
were also obtained of the 1986 Dec 13 transit of Pluto by Charon;
the event depth was about 0.07 mag less than predicted, which
supports the possibility of a dark equatorial band on Pluto as
suggested by Buie and Tholen (1986, Bull. AAS 18, 821)."
1987 January 26 (4303) Brian G. Marsden
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