Central Bureau for Astronomical Telegrams
IAUC 5270: 1991ac; 1991ab; 1991T; NO SN IN IC 4425
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Circular No. 5270
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1991ac IN ANONYMOUS GALAXY
C. Pollas, Observatoire de la Cote d'Azur, reports his discovery
of an apparent supernova of mag 18.5 on OCA Schmidt telescope
Tech Pan films exposed on Jan. 26.2 and 27.2 UT, the object being
located at R.A. = 12h58m55s.20, Decl. = +29 27'07".6 (equinox
1950.0). The host galaxy (mag 16) has its center located at R.A. =
12h58m55s.49, Decl. = +29 27'06".4. An Apr. 7.0 film shows nothing
at the position of SN 1991ac to a limiting magnitude of 21. Something
appears to be visible at the limit of exposures taken May 17.0
and 16.9, when the limiting magnitudes were 22 and 22.5, respectively.
SUPERNOVA 1991ab IN ANONYMOUS GALAXY
R. Kirshner and B. Schmidt, Center for Astrophysics, report:
"Spectrograms (420-910 nm) obtained at the Multiple Mirror Telescope
on May 16.3 UT show that SN 1991ab (IAUC 5267) is a type-Ia supernova
near maximum light. H-alpha emission from the spiral galaxy
yields a redshift of z about 0.064. Because this object is distant
and near maximum, photometry would be valuable."
SUPERNOVA 1991T IN NGC 4527
J. Holberg, M. Cheselka, R. Watkins, and K. Krug report the
following photometry obtained of SN 1991T at the 1.55-m telescope
atop Mt. Bigelow using the Catalina Photometer: Apr. 21.267 UT, V =
11.689 +/- 0.042, B-V = +0.061 +/- 0.035, U-B = -0.659 +/- 0.018;
Apr. 21.270, 11.702 +/- 0.042, +0.060 +/- 0.035, -0.675 +/- 0.019;
May 6.270, 11.804 +/- 0.056, +0.377 +/- 0.020, -0.206 +/- 0.024.
Color calibration was done with blue stars (B-V about -0.25).
Visual magnitude estimates (cf. IAUC 5259): May 7.00 UT, 11.6
(O. Skjaeraasen, Oslo, Norway); 12.12, 11.7 (R. Bunge, Lovettesville,
VA); 13.97, 12.3 (A. Pereira, Cabo da Roca, Portugal); 15.16,
12.0 (W. Wren, near Ft. Davis, TX); 16.90, 12.3 (P. Schmeer,
Bischmisheim, Germany).
NO SUPERNOVA IN IC 4425
J. Mueller reports that inspection by N. Reid of a red plate,
taken by Reid and R. Day in the course of the second Palomar Sky
Survey on 1987 Mar. 27, clearly shows an object at the position of
the supernova candidate 1991W reported on IAUC 5258.
1991 May 17 (5270) Daniel W. E. Green
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