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IAUC 5405: 1991bi; 1991bg; GRS 1715-44

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IAUC number

                                                  Circular No. 5405
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

SUPERNOVA 1991bi IN NGC 5127
     Further to IAUC 5404, C. Pollas reports that the supernova is
located at R.A. = 13h21m24s.75, Decl. = +31 49'28".6 (equinox
1950.0).  A star of magnitude B = 17.5 has end figures 28s.58,
03".2; another foreground star (B = 12.5) has end figures 14s.15,
     S. Benetti, E. Cappellaro, and M. Turatto, Asiago Observatory,
communicate:  "A spectrogram (range 390-800 nm, resolution 2.0 nm)
of SN 1991bi, obtained on Dec. 15.19 UT at the Cima Ekar 1.8-m
telescope (+ Boller & Chivens spectrograph + CCD), exhibits several
broad emission features (the strongest are measured at 462.5, 497.5,
561.0, and 662.3 nm) typical of a type-Ia supernova 3-4 weeks after
maximum.  However, the absorption feature at about 570.0 nm, usually
relatively strong in type-Ia supernovae at this phase, is missing."

SUPERNOVA 1991bg IN NGC 4374
     Benetti et al. also report:  "A spectrogram of SN 1991bg was
obtained on Dec. 14.15 (instrumentation details as given above).  A
preliminary reduction of the spectrum shows a very strong Si II line
at 617 nm, indicating this to be a type-Ia supernova not far from
maximum.  Also very strong is the other Si II line at 581 nm, and
also present are the S II lines at 534.5 and 550.5 nm.  Although the
continuum is relatively blue and no Na I D interstellar absorption
is visible, there are several similarities with the strongly reddened
SN 1986G in Cen A in the proximity of its maximum:  the slow
expansion velocity, the strength of Si II lines, and the absence of
the emission band at about 410 nm (visible in most of the type-Ia

GRS 1715-44
     N. Lund, S. Brandt, and A. J. Castro-Tirado, on behalf of the
Granat WATCH team (Danish Space Research Institute, Lyngby; and
Space Research Institute, Moscow), report:  "A gamma-ray burst, GRS
1715-44 (R.A. = 17h15m, Decl. = -44.1, equinox 1950.0, error radius
1 deg), was recorded by the WATCH all-sky x-ray monitor on Dec. 9.77
UT.  The event contained two pulses with 12-s separation.  Follow-up
observations are encouraged."

1991 December 16               (5405)             Daniel W. E. Green

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