Central Bureau for Astronomical Telegrams
IAUC 5645: 1992bg, 1992bh; 1992t
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Circular No. 5645
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVAE 1992bg AND 1992bh IN ANONYMOUS GALAXIES
J. Maza, University of Chile; and M. Hamuy, Cerro Tololo
Interamerican Observatory, report the discovery by R. Antezana,
University of Chile, of two supernovae on 20-min unfiltered IIa-O
plates taken by G. Valladares with the CTIO Curtis Schmidt
telescope. SN 1992bg (mpg about 17.8 on the Oct. 21.34 UT discovery
plate) is located about 3" west and 6" north of the nucleus of a
spiral galaxy at R.A. = 7h41m19s.0, Decl. = -62 24'06" (equinox
1950.0). SN 1992bh (mpg about 17.3 on the Oct. 21.32 discovery
plate) is located about 1" east and 2".5 south of the nucleus of a
spiral galaxy at R.A. = 4h58m40s.0, Decl. = -58 54'10". Confirmation
of both supernovae was made by M. Navarrete (CTIO) on CCD B,
V, and I images obtained on Oct. 24.31 with the CTIO 4-m telescope.
Spectrograms (range 320-750 nm) of both supernovae were obtained by
Hamuy on Oct. 27.2 with the CTIO 1.5-m telescope, showing the
characteristic Si II 635.5-nm feature of type-Ia supernovae. For SN
1992bg, the minimum of the Si II absorption yields an expansion
velocity of about 11 000 km/s with respect to the galaxy's rest
frame; this spectrum shows resemblance to that of the type-Ia SN
1992A taken 5 days past maximum light. The spectrum of the nucleus
of the parent galaxy seems to yield a redshift of z = 0.035. For
SN 1992bh, the minimum of the Si II absorption yields an expansion
velocity of about 12 000 km/s with respect to the galaxy's rest
frame; this spectrum shows resemblance to that of the type-Ia SN
1992A taken at maximum light. The redshift inferred from H-alpha
emission of the underlying galaxy is z = 0.044.
PERIODIC COMET SWIFT-TUTTLE (1992t)
S. Nakano, Sumoto, Japan, reports that Y. Kushida, Yatsugatake
South Base Obesrvatory, obtained photographs with a 0.25-m f/3.4
reflector, showing a faint tail about 2 and 1.6 deg long on Oct.
25.41 and 26.39 UT, respectively, toward the north-northeast.
There was no such long tail on Oct. 21, but there was an indication
of tail growing on Oct. 22.41.
Total visual magnitude estimates (cf. IAUC 5636): Oct. 17.99
UT, 6.9 (J. E. Bortle, Stormville, NY, 10x50 binoculars); 19.79,
6.9 (S. Canonaco, Genk, Belgium, 10x50 binoculars); 22.99, 6.7 (G.
R. Chester, Rixeyville, VA, 9x63 binoculars); 23.86, 6.4 (J. D.
Shanklin, Cambridge, England, 10x80 binoculars); 25.11, 6.3 (C. S.
Morris, near Pt. Conception, CA, 10x50 binoculars); 26.74, 6.5 (S.
Baroni, Milan, Italy, 20x80 binoculars); 28.01, 6.1 (D. W. E.
Green, Harvard, MA, 12x50 binoculars).
1992 October 28 (5645) Daniel W. E. Green
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