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IAUC 6647: 1997cl; X0726-260; GRS 1915+105

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IAUC number

                                                 Circular No. 6647
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

     The Mount Stromlo Abell Cluster Supernova Search Team (cf.
IAUC 6639) reports the discovery of an apparent supernova (R = 18.3)
on V and R CCD images taken on May 2 by S. Sabine on the Mount
Stromlo 1.27-m telescope (+ Macho Camera).  SN 1997cl is located
near Abell 3577 at R.A. = 13h54m18s.71, Decl. = -27o44'27".9
(equinox 2000.0).  A nearby star has position end figures 15s.02,
43'56".3.  SN 1997cl was also present on frames taken on Apr. 5 (R
= 18.0), but it is not visible on images taken on 1996 Aug. 5
(limiting mag R = 20.7).

     R. Corbet, Goddard Space Flight Center (GSFC) and Universities
Space Research Association, and A. Peele, GSFC and National
Research Council report: "A scan over the position of the transient
Be star x-ray source X0726-260 on May 5 with the PCA on RXTE
detected emission at a level of approximately 10 mCrab, showing the
source to be active.  An examination of the ASM light curve of
X0726-260, obtained between 1996 Jan. 5 and 1997 May 1, shows a
mean flux of approximately 2 mCrab, and the Fourier Transform of
this curve has its strongest peak at a period of 34.5 days and an
amplitude of approximately 1.6 mCrab.  A sine-wave fit at this
period yields maximum predicted flux on May 4, consistent with the
scan detection.  With this ephemeris the next predicted maximum is
on June 7, and further observations are encouraged at that time."

GRS 1915+105
     R. Remillard and E. Morgan, Massachusetts Institute of
Technology (MIT); J. Swank, Goddard Space Flight Center (GSFC); and
the RXTE ASM instrument team at MIT and GSFC report:  "The RXTE All
Sky Monitor has detected bright flares from GRS 1915+105, ending a
long interval of steady hard-x-ray emission at 200-300 mCrab (2-12
keV) that had been observed since early Dec. 1996.  Recent flares
reached 0.69 Crab on 1997 May 6.75 UT and 0.81 Crab on May 8.09.
The flares are evident on timescales at least as short as hours,
and there is a moderately softer x-ray spectrum at 2-12 keV.  We
encourage radio and infrared observations."

                      (C) Copyright 1997 CBAT
1997 May 8                     (6647)            Daniel W. E. Green

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