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IAUC 7611: 2001ay; SGR 1900+14; C/2001 A2

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                                                  Circular No. 7611
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/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

SUPERNOVA 2001ay IN IC 4423
     B. Swift and W. D. Li, University of California at Berkeley,
report the discovery by LOTOSS (cf. IAUC 7514) of an apparent
supernova (mag about 16.9) on an unfiltered CCD image taken on Apr.
18.4 UT with the 0.8-m Katzman Automatic Imaging Telescope (KAIT).
SN 2001ay, which was confirmed at mag about 17.0 on an image taken
on Apr. 19.2 by M. Schwartz with the 0.5-m Tenagra III automatic
telescope, is located at R.A. = 14h26m17s.00, Decl. = +26o14'55".8
(equinox 2000.0), which is 10".3 west and 9".3 north of the nucleus
of IC 4423.  A KAIT image of the same field taken on Apr. 4.4
showed nothing at this position (limiting mag about 18.5).

SGR 1900+14
     C. Guidorzi, F. Frontera, and E. Montanari, University of
Ferrara; L. Amati and M. Orlandini, Istituto Tecnologie e Studio
Radiazioni Extraterrestri, CNR, Bologna; E. Costa, M. Feroci, and
G. Gandolfi, Istituto Astrofisica Spaziale, CNR, Rome; J. J. M. in
't Zand, Astronomical Institute, University of Utrecht and Space
Research Organization Netherlands; and G. D'Andreta, BeppoSAX
Science Operation Center, report:  "A giant flare from SGR 1900+14
was detected by BeppoSAX on Apr. 18.33000 UT.  In the Gamma Ray
Burst Monitor (GRBM) energy band (40-700 keV), the flare shows a
fast rise (about 8 s) and a slow decay, with a total duration of
about 40 s.  Superposed to the time profile, the 5-s pulsation is
apparent.  The 40-700-keV peak flux, after deadtime correction, is
16 400 counts/s, corresponding to (1.1 +/- 0.1) x 10**-5 erg cm**-2
s**-1.  A preliminary analysis shows that the average GRBM spectrum
is consistent with a thermal bremsstrahlung (kT about 30 keV) plus
a hard tail.  Due to the brightness of the flare, the Wide Field
Camera unit 1 was automatically switched off after a few seconds.
Before that, it showed a peak flux in excess of 17 Crab units (2-28
keV).  The source position determined with the WFC is consistent
with that of SGR 1900+14, with an accuracy of 2'.1 (99-percent

     Visual m_1 estimates:  Mar. 31.42 UT, 6.9 (D. A. J. Seargent,
The Entrance, N.S.W., 10x50 binoculars); Apr. 11.76, 7.4 (A.
Baransky, Kiev, Ukraine, 0.11-m reflector); 13.84, 7.6 (W. Hasubick,
Buchloe, Germany, 25x100 binoculars); 14.38, 7.4 (Seargent); 16.16,
7.2 (C. S. Morris, Fillmore, CA, 20x80 binoculars); 18.37, 7.0
(Seargent, 2x20 binoculars).

                      (C) Copyright 2001 CBAT
2001 April 19                  (7611)            Daniel W. E. Green

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