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IAUC 2907: P/SCHWASSMANN-WACHMANN 1; 3U 1820-30; PG 2337+12; V616 Mon

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IAUC number 

                                                  Circular No. 2907
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
Western Union: RAPID SATELLITE CAMBMASS


PERIODIC COMET SCHWASSMANN-WACHMANN 1
     A. Mrkos, Klet Observatory, provides the following positions.
He notes that the magnitude was fainter than 18 on Dec. 5.7 and 9.7.

     1975 UT             R. A. (1950) Decl.         m1
     Dec. 28.72904     0 50 53.34   +15 31 33.0    14.8
          28.74351     0 50 53.58   +15 31 33.6
          29.73610     0 51 05.55   +15 31 15.9    15.0
          29.75045     0 51 05.80   +15 31 18.6
          31.77112     0 51 32.26   +15 30 51.6    15.0
          31.79080     0 51 32.39   +15 30 52.8


3U 1820-30
     G. Clark, Massachusetts Institute of Technology, reports that
the SAS-3 Group has found that the intense x-ray bursts from the
source 3U 1820-30 in NGC 6624 (cf. IAUC 2879) are recurrent.
Bursts were detected at times near those given by the sequence 1975
May 16.91310 + 0.18192 k UT, with k = 1-10, except that the burst
at k = 4 was unobserved on account of earth occultation.  The rms
deviation between the sequence times and the actual occurrence
times of the bursts is 527s, which is equivalent to a phase jitter
of 4.1 percent.  During 1976 Jan. 16-22 the source has been exceptionally
bright (its average intensity at 1-10 keV approximately
twice the Uhuru value), and observers are urged to monitor the
intensity at various frequencies during this high-intensity phase.


PG 2337+12
     W. Liller, Center for Astrophysics, reports that from a study
of 162 blue photographs in the Harvard collection L. J. Eachus
finds that PG 2337+12 (cf. IAUC 2892) varies irregularly between B
= 13.2 and 16.5.  No evidence of nova-like activity was seen on the
plates, which cover the periods 1890-1953 and 1970-1975.


V616 MONOCEROTIS
     J. Bortle, Brooks Observatory, provides further visual magnitude
estimates as follows: 1975 Nov. 16.42 UT, 12.4; Dec. 2.08,
12.6; 8.07, 12.6; 17.1, 13.0; 1976 Jan. 2.12, 13.2; 20.00, 13.2.


1976 January 30                (2907)              Brian G. Marsden

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