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IAUC 6661: 1997cn; GRB 970508

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                                                 Circular No. 6661
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997cn IN NGC 5490
     W.-d. Li, Y.-l. Qiu, Q.-y. Qiao, Y. Zhang, W. Zhou, and
J.-y. Hu, Beijing Astronomical Observatory (BAO), on behalf of the
BAO Supernova Survey, report the discovery of an apparent supernova
(mag about 15.8) on an unfiltered CCD frame taken with the BAO
0.6-m reflector on May 14.6 UT.  SN 1997cn is located at R.A. =
14h09m57s.76, Decl. = +17o32'32".3 (equinox 2000.0), which is 6".75
east and 11".7 south of the nucleus of NGC 5490.  The supernova was
confirmed on images obtained on May 15.  Unfiltered CCD images of
the same field taken on Apr. 30 (limiting mag about 18.0) show no
star at the position of the supernova.

GRB 970508
     M. Mignoli, C. Bartolini, A. Bragaglia, G. Clementini, A.
Comastri, and A. Guarnieri, Bologna Astronomical Observatory and
Bologna University; and F. Frontera, L. Nicastro, and E. Costa on
behalf of the BeppoSAX team report:  "Exposures in the Kron-Cousins
R band obtained with the 1.52-m telescope at Loiano on May 10.82-
10.88 UT show that Bond's variable (IAUC 6654) was at R = 19.78 +/-
0.05 (rms); no variability is detected among the four exposures
(limiting mag R about 21).  The observing time corresponds to the
maximum suggested by Djorgovski et al. (IAUC 6658), and our
measurements provide a better constraint to the lightcurve shape at
its peak.  Three R exposures obtained on May 9.84-9.89 do not
reveal the object (limiting mag R = 20.5).  The optical brightening
24 hr after the gamma-ray burst is similar to that seen for the GRB
970228 on images obtained at the Loiano telescope.  A finding chart
from the May 10.85 image is available at http://www.bo.astro.it."
     M. Garcia, D. Moraru, and J. McClintock, Harvard-Smithsonian
Center for Astrophysics; C. R. Robinson and C. Kouveliotou,
Universities Space Research Association and Marshall Space Flight
Center; and J. van Paradijs, University of Amsterdam and University
of Alabama, Huntsville, report:  "Observations with the Mount
Hopkins 1.2-m telescope in the R band during nonphotometric
conditions, spanning May 12.177-12.247 UT, show that the
counterpart found by Bond (IAUC 6654) was 0.77 +/- 0.09 fainter
than the star 13" to the north, corresponding to R = 20.47 +/- 0.09
using the calibration from Schaefer et al. (IAUC 6658).  Eleven
consecutive integrations of 300-s duration each are consistent with
a steady source having only the expected 0.08-mag statistical

                      (C) Copyright 1997 CBAT
1997 May 15                    (6661)            Daniel W. E. Green

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