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IAUC 7773: 2001ib; 51P

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                                                  Circular No. 7773
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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SUPERNOVA 2001ib IN NGC 7242
     T. Matheson, S. Jha, P. Challis, and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report that a spectrum (range
370-750 nm) of SN 2001ib (cf. IAUC 7768, 7772), obtained by W.
Brown on Dec. 10.08 UT with the F. L. Whipple Observatory 1.5-m
telescope (+ FAST spectrograph), shows it to be a type-Ia supernova
at maximum light.  Adopting the NASA/IPAC Extragalactic Database
recession velocity of 5790 km/s for the host galaxy, the supernova
expansion velocity is about 9700 km/s for Si II (rest 635.5 nm).
The spectral-feature age of the supernova (Riess et al. 1997, A.J.
114, 722) is 1 +/- 2 days after maximum light.  Several titanium
absorption features appear stronger than usual, indicating that
this may be a subluminous event similar to SN 1999by (see Garnavich
et al. 2002, Ap.J., in press, and
     A. V. Filippenko and R. Chornock, University of California,
Berkeley, report that inspection of CCD spectra (range 330-1000
nm), obtained on Dec. 11 UT with the Shane 3-m reflector at Lick
Observatory, reveals that SN 20001ib is of type Ia.  The spectral-
feature age (Riess et al., op.cit.) is 5 +/- 2 days past maximum
brightness.  The Si II 585-nm absorption might be somewhat stronger
than usual, relative to the Si II 615-nm line.

     Z. Sekanina, Jet Propulsion Laboratory, writes:  "Preliminary
analysis of the reported astrometric data for the two nuclei (IAUC
7769, MPEC 2001-X45) indicates that companion D separated from
primary A on Sept. 5.6 +/- 3.6 TT, or 3 months after perihelion,
with a relative deceleration of 59 +/- 8 units of 10**-5 the solar
attraction.  The two separation parameters are, however, highly
correlated and probably more uncertain than their formal errors
suggest.  Unless too faint, the companion should have shown up in
high-resolution images taken since mid-October, when it was about
4" to the west of the primary.  Predicted separation distances and
position angles (0h TT):  2001 Dec. 17, 12", 268 deg; 2002 Jan. 6,
10", 263 deg; Jan. 26, 9", 255 deg; Feb. 15, 9", 249 deg; Mar. 7,
11", 248 deg; Mar. 27, 15", 251 deg; Apr. 16, 19", 255 deg; May 6,
24", 259 deg."
     K. Kadota, Ageo, Saitama, Japan, reported CCD observations
that indicated an intrinsic brightening of more than two
magnitudes between Aug. 22 and Sept. 23 (an outburst confirmed by
other observers).

                      (C) Copyright 2001 CBAT
2001 December 13               (7773)            Daniel W. E. Green

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