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IAUC 6528: 1996cb; V2116 Oph; 118P

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                                                  Circular No. 6528
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 1996cb IN NGC 3510
     S. D. Van Dyk, Los Angeles, CA; R. A. Sramek, National Radio
Astronomy Observatory; M. J. Montes and K. W. Weiler, Naval
Research Laboratory; and N. Panagia, Space Telescope Science
Institute and European Space Agency, report the detection of radio
emission from the type-II supernova 1996cb on Dec. 21 with the Very
Large Array in configuration A:  "A radio-flux density of 2.41 +/-
0.14 mJy at 8.435 GHz (wavelength 3.6 cm) and 3.00 +/- 0.36 mJy at
14.965 GHz (2.0 cm) is measured at a position of R.A. =
11h03m42s.00, Decl. = +28o54'14".2 (equinox 2000.0), within 1" of
the optical position reported for the supernova (IAUC 6524).  A
detection of several mJy has also been obtained at 22.46 GHz
(wavelength 1.3 cm), but, due to atmospheric phase instabilities,
the flux density is being re-evaluated.  Radio monitoring is
continuing.  Since SN 1996cb is relatively nearby at about 8 Mpc,
study at other wavelengths is strongly recommended."

     J. Phillips, J. Greenhill and K. M. Hill, University of
Tasmania, report: "Using the Canopus 1-m telescope and CCD
photometer, we have monitored V2116 Oph (= GX 1+4) in V, R, I, and
H-alpha at frequent intervals during 1995 and 1996.  The H-alpha
flux, measured with a filter of bandwidth 10 nm, reached a peak
value for 1996 on or about Aug. 7 and then decreased to a minimum
about 3.5 mag fainter on Oct. 1; it remained near this lower level
until the end of observations on Oct. 20.  This level is consistent
with the absence of any line emission on Oct. 16 (cf. IAUC 6496).
The onset of decline coincides to within a few days with that in
the BATSE hard-x-ray emission (IAUC 6478).  V and I flux also
peaked on Aug. 7.  V decreased by at least 2 mag and was below
threshold (V > 20) during October.  The decrease in I was about 0.6
mag, indicating that companion emission dominates in this band."

     Total visual magnitude estimates:  Dec. 1.89 UT, 12.5 (K.
Hornoch, Lelekovice, Czech Republic, 0.35-m reflector); 13.94, 12.7
(R. J. Bouma, Groningen, The Netherlands, 0.25-m reflector); 29.50,
12.7 (A. Pearce, Woodend, Vic., Australia, 0.20-m reflector).

                      (C) Copyright 1996 CBAT
1996 December 31               (6528)            Daniel W. E. Green

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