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IAUC 5565: 1992ak; 1992ai, 1992aj; GAMMA-RAY BURSTS

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                                                  Circular No. 5565
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 1992ak IN UGC 3862
     E. Helin and K. Lawrence, Jet Propulsion Laboratory, report
the discovery by D. Moraru of an apparent supernova on films taken
by Helin et al. with the Palomar 0.46-m Schmidt telescope.  The
star is located in the southern spiral arm of UGC 3862, about 45"
from the galaxy's nucleus.  The discovery film taken Jan. 9.406 UT
shows SN 1992ak at mag 16.0, and a film taken Jan. 30.289 yields
mag 16.7, while no star is present at this position on a photograph
taken in 1991 January.  The following measurement of SN 1992ak from
the discovery photograph is by Moraru:  R.A. = 7h24m50s.52, Decl. =
+20 29'40".3 (equinox 1950.0).

     M. Della Valle and J. Melnick, European Southern Observatory,
report:  "Inspection of a spectrogram (range 400-840 nm, resolution
about 2 nm) of SN 1992aj, obtained with the New Technology Telescope
(+ EMMI) at La Silla on July 20.3 UT shows this object to be
a type-II supernova; the spectrum is dominated by H-alpha emission,
coupled with a weak P-Cyg profile.  Analysis of a spectrogram,
obtained as described above on July 21.3, shows SN 1992ai to be a
type-Ia supernova; the spectrum closely resembles that of SN 1989B
(Barbon et al. 1990, A.Ap. 237, 79), 3 weeks past maximum."

     T. L. Cline, Goddard Space Flight Center, NASA, on behalf of
the Ulysses/Compton/PVO Interplanetary Network team for the
triangulation of gamma-ray bursts (K. Hurley, M. Sommer, M. Boer, and M.
Niel for Ulysses; G. Fishman, C. Kouveliotou, C. Meegan, W.
Paciesas, and R. Wilson for Compton/Gamma Ray Observatory; E.
Fenimore, R. Klebesadel, and J. Laros for Pioneer/Venus Orbiter;
and T. Cline for Ulysses and BATSE), communicates:  "We report the
source location of the 1992 July 11 event of Earth-crossing time
58157.5 s, its center being at R.A. = 18h47m37s, Decl. = +73 00'.8
(equinox J2000.0), and the elliptical field of maximum likelihood
is slanted from R.A. about 282.1 deg, Decl. about +73.1 deg to R.A.
about 281.7 deg, Decl. = +72.9 deg.  Although the source field will
be considerably reduced with the final spacecraft calibration data,
the presently determined location is adequately small in extent to
warrant the encouragement of follow-up observations at other
energies. This is the first of several gamma-ray bursts occurring in
mid-July with the potential for precise source location."

1992 July 22                   (5565)            Daniel W. E. Green

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