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IAUC 6649: GRB 970508; 1997cl

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                                                 Circular No. 6649
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
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Phone 617-495-7244/7440/7444 (for emergency use only)


GRB 970508
     E. Costa, M. Feroci, L. Piro, P. Soffitta, L. Amati, and M. N.
Cinti, Istituto Astrofisica Spaziale, CNR, Frascati; F. Frontera
and G. Zavattini, Universita di Ferrara; L. Nicastro and E. Palazzi,
Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR,
Bologna; A. Tesseri, G. Gandolfi, M. Smith, D. Ricci, and A.
Coletta, BeppoSAX, Rome; J. Heise and J. in 't Zand, Space Research
Organization of the Netherlands, Utrecht; and M. Tavani, Columbia
Astrophysics Laboratory and Istituto di Fisica Cosmica e Tecnologie
Relative, CNR, Milano, report:  "The BeppoSAX Gamma Ray Burst
Monitor (GRBM) was triggered on May 8.904 UT.  A quick-look
analysis of the GRBM light curve shows a rather weak gamma-ray
burst (GRB) lasting about 15 s.  The intensity at its maximum is
about 450 counts/s.  The GRB was also detected by the Wide Field
Camera unit 2 with a maximum countrate of about 130 counts/s.
Taking into account the off-axis position, the peak flux
corresponds to about 1 Crab.  From the WFC image, we have derived a
preliminary position of R.A. = 6h54m21s, Decl. = +79o15'.8 (equinox
2000.0), with a 5' error radius.  One catalogued source lies within
the GRB WFC error box:  1RXS J065213.8+790855 is about 8' from the
GRB error-box center.  Observations in all bands are solicited."


SUPERNOVA 1997cl IN ANONYMOUS GALAXY
     S. Benetti, I. Hook, P. Shaver, and M. Turatto, European
Southern Observatory (ESO), communicate:  "A CCD spectrogram (range
374-691 nm, resolution 1.6 nm), obtained on May 9.09 UT with the
ESO 3.6-m telescope (+ EFOSC1) at La Silla, shows that SN 1997cl
(cf. IAUC 6647) is a peculiar type-IIn supernova.  The spectrum is
dominated by a relatively strong H-alpha emission on a relatively
red continuum.  The H-alpha profile appears to consist of three
components: one unresolved (centered at 687.4 nm), one intermediate
(FWHM 1500 km/s), and possibly a broad one (FWHM about 10 000 km/s).
A faint H-beta emission shows only the unresolved component.  The
Fe-II 516.9- and 501.8-nm lines are also visible with P-Cyg
profiles, from which an expansion velocity of about 1900 km/s is
derived.  The redshift of the parent galaxy (measured close to the
supernova position, using of H-alpha and [N II] 658.4-nm emission
lines and Ca II H and K absorption lines) is 0.047."

                      (C) Copyright 1997 CBAT
1997 May 9                     (6649)            Daniel W. E. Green

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