Central Bureau for Astronomical Telegrams
IAUC 7172: 1999cd; GRB 990510
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Circular No. 7172
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1999cd IN NGC 3646
P. Garnavich, S. Jha, R. Kirshner, and P. Challis, Harvard-
Smithsonian Center for Astrophysics, report that a spectrum of SN
1999cd was obtained by P. Berlind with the 1.5-m Tillinghast
telescope on May 15.3 UT. The spectrum shows a broad H-alpha
feature with a P-Cyg profile, indicating that the object is a type-
II supernova. Weaker He I 587.5-nm and H-beta features are also
present. The narrow emission lines from the host galaxy give a
recession velocity of 4260 km/s. The photospheric velocity of the
supernova, derived from the minimum of the H-alpha absorption, is
14 000 km/s, but the absorption extends to nearly 20 000 km/s.
F. Patat, European Southern Observatory (ESO); L. Rizzi,
Universita di Padova; and L. Guzzo and G. Guerrero, Osservatorio
Astronomico di Brera, communicate: "We have observed SN 1999cd
with the ESO 3.6-m telescope (+ EFOSC2) on May 19.09 UT at La
Silla. A full reduction of the CCD spectrogram (range 340-740 nm,
resolution 1.8 nm) shows spectral features (very-well-developed
P-Cyg profiles and a rather red continuum) that are consistent
with a supernova of type II, a few weeks after maximum light. The
most prominent features are identified as H-alpha, H-beta, H-gamma,
Na I D, Fe I, Ba II, Ti II, and Ca II. The expansion velocities
deduced from the minima of H-alpha and Ca II H and K are 13 600 and
9200 km/s, respectively. H-alpha shows a boxy absorption profile
and a rather flat-topped emission, with some possible structures.
The recession velocity of NGC 3646 at the supernova's location,
deduced from the narrow H-alpha probably coming from an underlying
H II region, is 4390 km/s. The magnitude of SN 1999cd is R about
17.4."
GRB 990510
S. Covino, Osservatorio Astronomico di Brera, reports on
behalf of a large collaboration (including D. Lazzati, G.
Ghisellini, P. Saracco, S. Campana, G. Chincarini, S. Di Serego, A.
Cimatti, L. Vanzi, L. Pasquini, F. Haardt, M. Vietri, L. Stella, H.
Boehnhardt, F. Bresolin, P. Moller, and G. Rupprecht): "We made
R-band imaging polarimetry of the optical transient associated to
GRB 990510 at the Very Large Telescope of the European Southern
Observatory on May 11.13509 UT, when object was at R = 19.1 +/-
0.02. We found linear polarization at the level of 1.7 +/- 0.2
percent with p.a. 11 +/- 3 deg, relative to the stars in the field."
(C) Copyright 1999 CBAT
1999 May 19 (7172) Daniel W. E. Green
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