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IAUC 7414: Mkn 421; 2000cc; 2000bk; 2000cb

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IAUC number

                                                  Circular No. 7414
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
Phone 617-495-7244/7440/7444 (for emergency use only)

     D. J. Fegan and S. Dunlea, University College, Dublin; H.
Badran, M. Catanese, S. Fegan, D. Horan, and T. C. Weekes,
Smithsonian Astrophysical Observatory; J. Buckley, Washington
University; J. Finley, Purdue University; F. Krennrich, Iowa State
University; and J. Rose, University of Leeds, on behalf of the
Whipple Observatory Gamma-Ray Collaboration, report significantly
increased TeV-gamma-ray emission from Markarian 421 during Apr. 27-
May 1:  "All observations were taken above an elevation of 50 deg
with the 490-pixel Imaging Atmospheric Cerenkov Telescope, at an
operating threshold of about 275 GeV.  Preliminary analysis yields
detected rates, expressed in units of the Crab-nebula TeV rate, as
follows:  Apr. 26, 0.32 +/- 0.18; 27, 1.47 +/- 0.07; 28, 1.24 +/-
0.07; 29, 0.98 +/- 0.07; 30, 2.90 +/- 0.08; May 1, 1.22 +/- 0.08.
Observations taken on Apr. 30 are particularly interesting,
exhibiting an almost uniform increase in event rate over a 2-hr
period, from a baseline value of < 0.4 Crab at the start to a rate
of 4.7 Crab at the maximum of the flare.  Thereafter, the flare
decayed slowly over a further 2-hr period, reaching a rate of 2.4
Crab when tracking observations ceased."

SUPERNOVA 2000cc IN CGCG 140-014
     G. Aldering and A. Conley, Lawrence Berkeley National
Laboratory, write:  "An optical spectrum (range 330-900 nm, with
S/N about 11/nm) of SN 2000cc (cf. IAUC 7413), taken with the Cerro
Tololo 4-m telescope (+ RC spectrograph) on May 2.4 UT, exhibits a
featureless spectrum, consistent with that of a blackbody of about
8500 K.  This object may prove to be a supernova at a very early
epoch, and we encourage further monitoring."

SUPERNOVA 2000bk IN NGC 4520
     Further to their item on IAUC 7408, Jha et al. report that
their spectrum of SN 2000bk does not show interstellar Na I D
absorption from the host galaxy; the Na I D feature reported there
was misidentified.

SUPERNOVA 2000cb IN IC 1158
     K. Krisciunas, University of Washington; and N. C. Hastings
and R. McMillan, Apache Point Observatory (APO), report preliminary
photometry (uncertainities +/- 0.02 mag) of SN 2000cb, using the
APO 3.5-m telescope (+ software aperture of diameter 4".5):  May
1.41 UT, V = 17.96, B-V = +0.88, V-R = +0.41, V-I = 0.60.

                      (C) Copyright 2000 CBAT
2000 May 2                     (7414)            Daniel W. E. Green

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