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IAUC 3075: X-RAY BURSTS; 1975n

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IAUC number 

                                                  Circular No. 3075
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


X-RAY BURSTS
     W. H. G. Lewin, J. A. Hoffman, J. Doty, F. K. Li and J. E.
McClintock, Massachusetts Institute of Technology, report that they
have detected with the SAS-3 Observatory 26 x-ray bursts from
MXB1735-44 between May 1d00h and May 8d05h UT.  The preliminary
error box for this source has a radius of ~ 10'; it includes 3U
1735-44, and they have no doubt that this strong x-ray source produced
the bursts.  The bursts are unusually short in duration (3-7
seconds).  Near May 3d06h UT the bursts seemed to appear regularly
with intervals of about 50 min; seven bursts were detected in 7.5
hr.  However, most of the time the intervals were irregular; there
were five occasions where bursts were separated by more than 12 hr.
Although the maximum burst luminosity (assuming a distance of 10
kpc for the source) was only ~ 2-6 x 10**38 erg/s (1-30 keV) and the
burst spectra were not unusually hard, the positional coincidence
and the short burst duration make it likely that this source is the
burst source KGX 345-6 (cf. IAUC 2959).

     Lewin et al. add that, as reported on IAUC 3067, the rapid
burster MXB1730-335 is in an active state.  Bursts were observed by
SAS 3 during Apr. 30d00h-22h UT (at intervals of from 25 to 120
seconds), May 5d15h-16h (intervals 35s-65s) and May 8d05h-11h
(intervals 90s-250s).


COMET WEST (1975n)
     The following precise positions (of Nucleus A) have been
obtained by G. Schwartz and C.-Y. Shao with the 155-cm reflector at
the Agassiz Station of the Harvard College Observatory.  Measurers:
Shao and J. H. Bulger.

     1976 UT             R. A. (1950) Decl.
     July 23.08896    17 24 57.58   + 6 13 54.4
          23.25394    17 24 49.53   + 6 11 37.0
          25.21819    17 23 19.46   + 5 44 29.9

Separations and position angles of Nucleus B (with respect to Nucleus
A) were as follows: July 23.09 UT, 34".0, 318o; 23.25, 34".1,
316o; 25.22, 34".2, 317o.  Those of Nucleus D were: July 23.09 UT,
18".0, 318o; 23.25, 18".3, 317o; 25.22, 19".1, 316o.


1977 May 16                    (3075)              Brian G. Marsden

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