Central Bureau for Astronomical Telegrams
IAUC 7332: 1999gk; GRB 991208
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Circular No. 7332
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1999gk IN NGC 4653
S. Jha, P. Garnavich, P. Challis, and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report the serendipitous
discovery by P. Berlind of a supernova in NGC 4653, during the
course of spectroscopic observations with the F. L. Whipple
Observatory (FLWO) 1.5-m telescope (+ FAST spectrograph). A
spectrum of SN 1999gk, taken by Berlind on Dec. 15.53 UT, shows it
to be a type-II supernova just after maximum light. The spectrum
exhibits a blue continuum with strong P-Cyg Balmer lines and Fe II
absorption. The H-alpha profile is quite peculiar, with the P-Cyg
absorption showing two minima at expansion velocites of 16 100 and
8300 km/s, perhaps implying an asymmetric expansion and the
possibility of strong polarization. Superimposed narrow H-alpha
emission yields a recession velocity of 2490 km/s for the host
galaxy. Concurrent images, taken by C. Hergenrother with the FLWO
1.2-m telescope (+ 4Shooter), yield a precise position for the
supernova of R.A. = 12h43m51s.91, Decl. = -0o32'55".4 (equinox
2000.0), which is 45".6 north and 15".3 east of the host galaxy,
and magnitudes for the supernova V = 15.7 and R = 15.8.
Coincidentally, the supernova is in the Landolt standard star field
SA104.
GRB 991208
A. J. Castro-Tirado, Laboratorio de Astrofisica Espacial y
Fisica Fundamental del Instituto Nacional de Tecnica Aerospacial,
Madrid, and Instituto de Astrofisica de Andalucia, Granada, on
behalf of a large European collaboration; C. Blake and J. Wall,
University of Oxford; and G. Feulner and U. Hopp, Universitats
Sternwarte, Hamburg, report: "We have imaged the 14 arcmin**2 error
box derived by the Ulysses, KONUS, and NEAR spacecraft for the
extremely intense gamma-ray burst detected on Dec. 8.19227 UT
(Hurley et al., GCN 450). The images were taken with the 2.5-m
Isaac Newton telescope (INT) at La Palma on Dec. 10.27 (I band) and
at the 2.5-m INT and 2.2-m telescope of the German-Spanish Calar
Alto Observatory on Dec. 11.27 (R- and I-band filters). After a
visual comparison with the Digital Sky Survey, a new source is
clearly detected with R = 19.5 +/- 0.1 (Dec. 11.27). Its position
is R.A. = 16h33m53s.51, Decl. = +46o27'21".5 (equinox 2000.0; +/-
1"). This object coincides with the previously unknown radio
source reported by Frail et al. at position end figures 53s.50,
20".9 (GCN 451) and therefore is taken to be the optical afterglow
to GRB 991208. Further multiwavelength imaging and spectroscopy
are encouraged. A finding chart is posted at
http://www.laeff.esa.es/~ajct/GRBs/GRB991208."
(C) Copyright 1999 CBAT
1999 December 16 (7332) Daniel W. E. Green
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