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IAUC 3458: MXB 1730-335

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                                                  Circular No. 3458
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 617-864-5758

MXB 1730-335
     O. P. N. Calla, S. Barathy and A. K. Snagal, Space Applications
Centre; and S. M. Bhandar, M. R. Deshpande and H. O. Vyas,
Physical Research Laboratory, Ahmedabad, telex: "Following the
discovery of microwave bursts from the Rapid Burster MXB 1730-335 in
1979 Apr. (cf. IAUC 3347), we report additional observations of a
new type of microwave bursting pattern similar in character to that
observed at x-ray wavelengths (cf. IAUC 3392; Inoue et al. 1980,
Nature 283, 358).  The details of receiving and recording systems
used for these observations may be found on IAUC 3347.  The
characteristics of the observed bursts are:

     1979 UT                         d(b)    R      D     A
     Aug. 20d15h26m12s-20d15h34m12s  480s  60-90s  12s   0.25
          20 15 12 30 -20 15 20 25   470     5    60-90  0.25
     Sept.18 13 09 30 -18 13 11 24   114     5     20    0.3
          21 12 40 00 -21 12 40 48    48     5     10    0.3

Here d(b) is the duration of an individual burst, R the risetime,
D the decay time and A the peak amplitude (in db)   The two bursts
observed on 1979 Aug. 20 have profiles altogether different from
those observed during 1979 Apr.; in place of a short (10-20 s)
duration Gaussian-like time profile, these bursts have a long-duration
(9 min) flat-top profile and a relatively shorter and more irregular
decay.  Similar bursts of relatively shorter duration were observed
on 1979 Sept. 18 and 21.  At the end of the present series
of observations, the burst durations and shapes seem to be approaching
the characteristics of bursts observed during 1979 Apr.  These
observations confirm that the Rapid Burster produces bursts of
microwave emission broadly similar in characteristics to those at
x-ray wavelengths.  Simultaneous x-ray and microwave data are
required to study the relationship between the two bursting processes,
especially in view of a similar change in the bursting pattern observed
at both wavelengths.  In light of our detection of microwave
bursts from the Rapid Burster, we suggest efforts be made to
observe the x-ray bursters, including MXB 1730-335, at microwave
frequencies during the 1980 world-wide watch.  Ground-based microwave
observations can enhance long-term monitoring of the x-ray bursters."

1980 March 13                  (3458)              Daniel W. E. Green

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