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IAUC 3098: RY Sgr; P/ENCKE; (69)

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IAUC number 

                                                  Circular No. 3098
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


RY SAGITTARII
     P. L. Collins, Steward Observatory, suggests that this R CrB-type
variable is fading.  Recent magnitude estimates, some communicated
by J. Mattei, AAVSO, are: Aug. 18.1 UT, 6.5 (L. C. Peltier,
Delphos, Ohio); 22.23, 7.4 (Collins); 23.08, 7.8 (J. Bortle, Brooks
Obs.); 24.2, 7.5 (Collins); 25.15, 7.7 (C. Hurless, Lima, Ohio).


PERIODIC COMET ENCKE
     The following semiaccurate position, by Iwahana, Shizuoka (16-cm
reflector) is from Orient. Astron. Assoc. Comet Bull. No. 150:

     1977 UT             R. A. (1950) Decl.         m1
     July 14.76458     5 39 12      +29 27.2     ~12-13

     J. Bortle, Brooks Observatory, communicates the following visual
visual magnitude estimate and coma diameter, obtained with a
32-cm reflector in excellent conditions: July 23.34 UT, ~ 10.2, 30".

     Z. Sekanina, Center for Astrophysics, informs us that in
September and October attempts should be made to detect a cloud of
submillimeter-sized and larger meteoric debris ejected from this comet;
it should show up as a faint short tail essentially to the west of
the nucleus.  Schmidt telescopes or similar instruments and use of
calibrated panchromatic plates combined with a red filter are most
appropriate for this search.  Negative observations of high quality
should also be communicated.  The comet will be observable from
southern latitudes, and the ephemeris is on IAUC 3072.


(69) HESPERIA
     E. Bowell writes: "On Sept. 28 this object will attain the
extremely small phase angle of 0o.03.  This event will offer the rare
opportunity to observe the surge in brightness of a minor planet
very close to zero phase.  The phase angle will be less than 0o.1
from 11h to 23h UT, so observations from Japan and Australasia will
be particularly valuable.  Accurate photoelectric photometry is
required during this interval and for some days preceding and
following opposition.  The ephemeris is in Efemeridy Malykh Planet for
1977, p. 160.  Observers interested in participating in this project
should contact me at Lowell Observatory, Flagstaff, AZ 86002,
U.S.A.  (telephone 602-774-3358) as soon as possible."


1977 August 25                 (3098)              Brian G. Marsden

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