Central Bureau for Astronomical Telegrams
IAUC 6512: 1996bw; SGR 1806-20
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Circular No. 6512
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
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)
Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 1996bw IN NGC 664
W. Li, Q. Qiao, Y. Qiu, and J. Hu, Beijing Astronomical
Observatory (BAO), report the discovery by the BAO Supernova Survey
of a supernova located 19".7 west and 3".3 south of the center of
NGC 664 (R.A. = 1h43m46s, Decl. = +4o13'.3, equinox 2000.0). The
following magnitudes of SN 1996bw were derived from unfiltered CCD
images taken with the 0.60-m BAO reflector: Nov. 30, about 17.5;
Dec. 2, 17.2. Unfiltered CCD images of the same field (limiting
mag about 19.0) taken on Nov. 15 and 26 show no star at the
position of SN 1996bw. A low-resolution, low-signal-to-noise
spectrogram (0.96 nm/pixel, range 350-900 nm), taken with the BAO
2.16-m telescope by Li, J. Wei, and D. Xiu on Dec. 2.50 UT,
suggests that this may be a type-Ib supernova prior to optical
maximum; the spectrum is very blue, with no clear classification
features. The overall spectrum is similar to that of SN 1984L (a
prototype type-Ib supernova) at earlier times, but far bluer.
There is conspicuous He I 570-nm absorption at 579 nm and Fe II
absorption at 480 nm. The expansion velocity of the SN envelope is
about 10 500 km/s, derived from the He I 570-nm feature. The
redshift of the galaxy (derived from the narrow H-alpha emission of
the H II region) is 5563 km/s.
SGR 1806-20
K. Hurley, Space Sciences Laboratory, University of
California, Berkeley, on behalf of the Ulysses Gamma-Ray Burst
Team; C. Kouveliotou, Universities Space Research Association and
Marshall Space Flight Center (MSFC), NASA; G. J. Fishman and C. A.
Meegan, MSFC; and J. van Paradijs, University of Amsterdam and
University of Alabama, Huntsville, report: "We have derived a
much-refined position for the transient soft-gamma-ray repeater
reported on IAUC 6501, via triangulation between Ulysses and BATSE
of two bursts on Nov. 19. The position is an annulus whose radius
is 76.990 deg, whose halfwidth is 0.0092 deg (3-sigma confidence
level), centered at R.A. = 23h55m34s.9, Decl. = -30 55'55" (equinox
2000.0). The combined triangulation annuli and BATSE error circles
give error boxes whose areas are more than a factor of 100 smaller
than the BATSE error circles alone. They are consistent with the
known position of SGR 1806-20 (Murakami et al. 1994, Nature 368,
127), and the two annuli midlines pass within 4" of this position.
We conclude that the source of these bursts, as well as of the ones
that have occured since Oct. 30, is indeed SGR 1806-20. The latest
short, soft event from this source was detected with BATSE on Nov.
23, so continued monitoring at other wavelengths is strongly
encouraged."
(C) Copyright 1996 CBAT
1996 December 2 (6512) Daniel W. E. Green
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