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Circular No. 7414 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) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304 Phone 617-495-7244/7440/7444 (for emergency use only) MARKARIAN 421 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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