Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 4303: 1987d; 1987b; PLUTO

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).

Read IAUC 4302  SEARCH Read IAUC 4304
IAUC number

                                                  Circular No. 4303
Central Bureau for Astronomical Telegrams
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

     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.

     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).

     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

Read IAUC 4302  SEARCH Read IAUC 4304

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!