Central Bureau for Astronomical Telegrams
IAUC 6674: 1997cq; GRB 970508
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Circular No. 6674
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 1997cq IN ANONYMOUS GALAXY
The McDonald Observatory Supernova Search Team (M. T. Adams,
D. A. Howell, M. H. Ward, J. C. Wheeler, and W. Wren) report their
discovery of an apparent supernova on three Kron-Cousins R-band CCD
images of Abell 2199 (z = 0.0299) taken during June 2.274-2.286 UT
with the 0.76-m telescope. SN 1997cq is located at R.A. =
16h29m50s.86, Decl. = +39o45'20".3 (equinox 2000.0), which is 39"
south of the nucleus of a barred spiral galaxy. Preliminary CCD
photometry between June 4.146 and 4.226 yields V = 19.23, B-V =
+0.13, V-R = +0.09, V-I = +0.36. SN 1997cq is not visible on R-
band images (limiting mag about 21) taken on 1995 July 5, 1996 Mar.
12 and 29, and Oct. 7.
GRB 970508
A. Fruchter and L. Bergeron, Space Telescope Science Institute;
and E. Pian, ITESRE, CNR, Bologna, on behalf of a large
collaboration, report: "The proposed optical counterpart of GRB
970508 (IAUC 6654) was imaged with the Hubble Space Telescope,
using the STIS CCD (+ clear filter) in four 1250-s exposures and
the NICMOS Camera 2 (+ F160W filter) in four 500-s exposures during
June 2.52-2.66 and 2.67-2.74 UT, respectively. The optical source
is detected in the STIS image at magnitude R = 23.10 +/- 0.15.
This and previous ground-based R-band observations are consistent
with a power-law fading of the source after May 10 with an index of
-1.1. The NICMOS image yields magnitude H = 20.3 +/- 0.3, or 6.5
+/- 2.0 microJy. The primary uncertainties in both these
measurements are due to our imperfect knowledge of the calibration
of these two new instruments. No significant evidence of
nebulosity is seen in either the STIS or NICMOS imaging. A compact
galaxy coincident with the optical source brighter than R = 24.3
would, by now, have produced a noticeable flattening of the power-
law fall-off of the source luminosity with time. Similarly, a
galaxy 1" in diameter that is also brighter brighter than R = 25
would be visible in the image after a point-spread function is
subtracted from the position of the source. Nebulosity, such as
that seen surrounding GRB 970228 (Sahu et al. 1997, Nature 387,
476), would be readily apparent. The only visible galaxies within
a few arcsec of the source have integrated magnitudes fainter than
R = 24.5. Therefore, if the source is at the redshift (z = 0.835)
of the most distant absorption system seen in the spectrum (IAUC
6655), the host galaxy must be at least several times less luminous
than the knee of the Schechter galaxy luminosity function, L*."
(C) Copyright 1997 CBAT
1997 June 5 (6674) Daniel W. E. Green
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