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IAUC 7619: 2001bb; GU Sgr; 2000 GN_171; 45P

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                                                  Circular No. 7619
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 2001bb IN IC 4319
     T. Matheson, S. Jha, P. Challis, and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report that a spectrum of SN
2001bb, obtained by P. Berlind on May 2.27 UT with the Mt. Hopkins
1.5-m telescope (+ FAST spectrograph), shows it to be a type-Ic
supernova near maximum light.  The spectrum is very similar to that
of SN 1994I at 4 days before maximum (see Figure 1 of Filippenko et
al. 1995, Ap.J. 450, L11), although SN 2001bb appears to be more
reddened.  It does not appear to be similar to the spectra of
hypernovae (cf. IAUC 7616) such as SN 1998bw (Iwamoto et al. 1998,
Nature 395, 672) or SN 1997ef (Iwamoto et al. 2000, Ap.J. 534, 660).

     E. O. Waagen, American Association of Variable Star Observers,
reports that, according to the AAVSO International Database, the
last fading of this R Crb-type variable began between Dec. 1987 and
Feb. 1988 (when it reached minimum visual mag about 16.3), before
it returned to full maximum at m_v = 10.4 in Feb. 1993.  Since then,
GU Sgr has been observed around maximum until it was found to have
faded this past month.  Recent magnitude estimates reported to the
AAVSO (visual unless otherwise noted):  Apr. 15.27 UT, [12.4 (S.
Otero, Buenos Aires, Argentina); 16.330, 14.3 (S. O'Connor, Montreal
North, QC; CCD V); 20.356, 14.3 (O'Connor); 25.622, [14.2 (R.
Stubbings, Druin, Victoria, Australia); 30.847, [14.5 (A. Pearce,
Nedlands, W. Australia); May 2.835, [14.6 (Pearce); 3.848, [14.5

2000 GN_171
     S. S. Sheppard, University of Hawaii (UH), writes: "R-band CCD
photometry with the UH 2.2-m telescope of the transneptunian object
2000 GN_171 (ephemeris on MPEC 2001-G04) during Apr. 20-25 shows a
single-peaked rotational lightcurve.  It has a peak-to-peak
variation of 0.6 magnitude and a period of 4.15 +/- 0.05 hr, though
an alias period of about 3.5 hr is possible.  The object could be
elongated with a double-peak of about 8.3 hr."

     Visual m_1 estimates: Apr. 12.12 UT, 9.4 (A. Hale, Cloudcroft,
NM, 0.2-m reflector); 13.84, 9.2 (R. J. Bouma, Groningen, The
Netherlands, 0.25-m reflector); 22.47, 10.2 (K. Yoshimoto,
Yamaguchi, Japan, 0.25-m reflector); 26.84, 10.1 (W. Hasubick,
Buchloe, Germany, 0.44-m reflector).

                      (C) Copyright 2001 CBAT
2001 May 4                     (7619)            Daniel W. E. Green

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