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IAUC 3349: 4U 1608-52; V1668 Cyg (N Cyg 1978); MXB1730-335

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IAUC number

                                                  Circular No. 3349
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

4U 1608-52
     M. Oda, Institute of Space and Aeronautical Science, University
of Tokyo, communicates: "The Hakucho observing team (Japanese
X-Ray Observatory, CORSA-B) has discovered intense x-ray bursts
from a source in Norma located within an error circle of radius 0o.5
centered on the position of 4U 1608-52 (Fabbiano et al. 1978, Astrophys.
J. 221, L49).  Two burst events recorded on Apr. 9d08h29m41s
and 16d18h09m51s UT are similar in size (intensity ~ 8 x Crab in
the 2-12-keV range) and have a shape typical of a burster.  The
burst size is consistent with that previously recorded by Vela
satellites (Belian et al. 1976, Astrophs. J. 206, L135).  A bright
and apparently steady x-ray source at 0.5 Crab has been present
prior to and through the bursts within the same error circle and is
most probably associated with the bursts.  4U 1608-52 has been
previously identified with a reddened star of magnitude 18.2 (Grindlay
and Liller 1978, Astrophys. J. 220, L127)."

     L. Kaluzienski and S. Holt, Goddard Space Flight Center,
report the detection of an outburst from the region (error circle
radius ~ 2o) centered on the position of the recurrent transient 4U
1608-52 with the Ariel 5 all-sky monitor.  The flare commenced on
Apr. 9 with a flux (3-6 keV) of ~ 0.2 Crab recorded at that time.
A rapid brightening to a level of ~ 0.6 Crab was observed during
Apr. 12-15, and the source was still bright when last observed on
Apr. 22.  It is noted that the last flare from 4U 1608-52 occurred
in late January (IAUC 3328) and that both the latter event and the
recent outburst of Aql X-1 (IAUC 3342) have been subsequently
confirmed with the solid-state spectrometer aboard the Einstein
Observatory HEAO 2.

     Visual magnitude estimates: 1978 Nov. 11.90 UT, 10.2 (D. P.
Elias, Athens Observatory); 25.73, 10.3 (Elias); Dec. 9.75, 10.4
(G. M. Hurst, Northampton, Eng.); 19.88, 10.5 (Hurst); 1979 Jan.
13.77, 10.8 (Hurst); Apr. 3.50, 12.1 (P. L. Collins, Tucson, AZ).

     Corrigendum.  The names of the authors of the item on IAUC
3344 should be given in the order Ashok, Kulkarni, Apparao, Chitre.

1979 April 24                  (3349)              Brian G. Marsden

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