Central Bureau for Astronomical Telegrams
IAUC 7772: 2001ig; 2001ib
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Circular No. 7772
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
SUPERNOVA 2001ig IN NGC 7424
R. O. Evans, Hazelbrook, New South Wales, reports his visual
discovery with a 0.31-m reflector on Dec. 10.43 UT of an apparent
supernova (mag about 14.5) located 120" east and 100" north of the
nucleus of NGC 7424. The object was confirmed visually by B.
White, Linden, N.S.W., on Dec. 10.45 and via CCD by C. Bembrick,
Napoleon Reefs, N.S.W., on an image taken on Dec. 10.55 (mag 15.1;
offset 139" east and 109" north). Bembrick noted that nothing is
visible on the Digitized Sky Survey at the position he measures for
SN 2001ig: R.A. = 22h57m30s.69, Decl. = -41o02'25".9 (equinox
2000.0). An image taken a day later by Bembrick indicates that the
new object had brightened to mag 14.85.
M. M. Phillips, Observatories of the Carnegie Institute of
Washington (OCIW); and N. B. Suntzeff, Cerro Tololo Interamerican
Observatory (CTIO), report that SN 2001ig was observed by Suntzeff
and K. Krisciunas (CTIO) with the facility CCD imager on the 1.5-m
CTIO telescope, yielding the following photometry: Dec. 12.1 UT, V
= 14.26, B-V = -0.05; Dec. 13.0, V = 14.24. Spectroscopic
observations were obtained by R. Carlberg (University of Toronto)
on Dec. 11 and by M. Gladders (OCIW) and F. Barrientos (Pontificia
Universidad Catolica de Chile) on Dec. 13 with the 6.5-m Baade
Telescope at Las Campanas Observatory; these data were reduced by
T. Matheson and S. Jha (Harvard-Smithsonian Center for
Astrophysics). The first of these spectra shows only a few broad
absorption features at 400, 425, 460, and 525 nm, and it defies
simple classification. The Dec. 13 spectrum shows a broad P-Cyg
feature with a peak at about 650 nm and blue-shifted absorption at
612 nm. Also visible are broad absorption features at 408, 458,
and 556 nm. The general aspect of this spectrum is similar to
early spectra obtained of the type-IIb supernova 1987K (see
Filippenko 1988, A.J. 96, 1941), although SN 2001ig is much bluer.
If this is true, the P-Cyg feature would be H-alpha, and the other
absorptions would correspond to H-gamma, H-beta, and He I 587.6-nm
at expansion velocities of 15 000-20 000 km/s. However, further
spectroscopy will be needed to confirm these provisional
identifications.
SUPERNOVA 2001ib IN NGC 7242
Further to IAUC 7768, R. Arbour reports that he has found
another image of SN 2001ib (at about the same brightness as on Dec.
7) taken on Dec. 5.813 UT; the image is trailed due to improper
tracking.
(C) Copyright 2001 CBAT
2001 December 13 (7772) Daniel W. E. Green
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