Central Bureau for Astronomical Telegrams

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IAUC 6505: 1996bu; LEONID METEORS 1996

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                                                  Circular No. 6505
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
Phone 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 1996bu IN NGC 3631
     S. Nakano, Sumoto, Japan, communicates that Reiki Kushida,
Yatsugatake South Base Observatory, reports her discovery on an
unfiltered CCD image taken on Nov. 14.793 UT with a 0.40-m f/5
reflector of an apparent supernova (mag 17.3) located at R.A. =
11h20m59s.18, Decl. = +53 12'08".0 (equinox 2000.0; measurement by
Y. Koshida), which is 32" west and 117" north of the center of NGC
3631.  No star at this position is visible on her frames taken on
1996 Feb. 13 and May 9.
     P. Garnavich, P. Challis, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, report that C. Hergenrother and W. Brown
obtained CCD images of SN 1996bu with the Whipple Observatory's
1.2-m reflector on Nov. 17.49 UT, yielding V = 17.6 and B = 18.1
and position end figures 59s.30, 08".4 for the supernova.  Spectra
obtained with the Multiple Mirror Telescope by R. Marzke and S.
Odewahn on Nov. 18.5 show SN 1996bu to be a peculiar type-II
supernova.  Narrow Balmer emission lines are seen above a blue
continuum; the continuum becomes flat shortward of 500 nm.  The
widths of the lines are 1400 km/s FWHM after correcting for the
spectral resolution; at the base of the H-alpha emission, the full
width increases to 5500 km/s.  The H-alpha emission centroid is
redshifted by 1140 km/s, which is close to the velocity of 1156
km/s for NGC 3631.  There is no evidence of broad P-Cyg features
seen in normal type-II supernovae.  Deep absorption features of Na
I 590.7-nm (0.4 nm equivalent width) and Ca II 395.7-nm (1.5 nm EW)
are seen and may be due to interstellar or circumstellar gas.

     Numerous observers have reported observations that suggest a
moderate 1996 display of particularly bright Leonid meteors.  J.
Rendtel and R. Arlt, International Meteor Organization, report no
distinct peak but rather a plateau of activity (ZHR > 30;
calculated with population index 1.8) between Nov. 17.05 and 17.60,
with somewhat higher rates (ZHR about 60) during Nov. 17.2-17.4.
J. E. Bortle, Stormville, NY, reports that the display on Nov. 17
UT was similar to the 1961 display of unusually bright meteors.  P.
Jenniskens (Ames Research Center), P. Brown (University of Western
Ontario), and R. Keen (Coal Creek Canyon, CO) also remarked on the
bright meteors, Keen noting that all Leonids observed during Nov.
17.32-17.42 left trains that lasted in most cases for about one
second (the brightest such meteor having mag -6), and Brown noting
seven fireballs in the magnitude range -4 to -8 during Nov.

                      (C) Copyright 1996 CBAT
1996 November 18               (6505)            Daniel W. E. Green

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