Circular No. 5233 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 1991O IN ANONYMOUS GALAXY J. Mueller reports her discovery of a supernova of red magnitude about 18, located at R.A. = 14h23m33s.9, Decl. = +65 59'06".8 (equinox 1950.0); the galaxy's center is located at R.A. = 14h23m32s.3, Decl. = +65 59'01".6. The discovery plate was taken by Mueller on Mar. 18 UT with the 1.2-m Oschin Telescope in the course of the second Palomar Sky Survey. A. V. Filippenko, University of California at Berkeley, reports that a spectrogram (range 390-700 nm, resolution 1.5 nm) of SN 1991O, obtained on Apr. 7 UT with the Shane 3-m reflector at Lick Observatory, shows it to be a type-Ia supernova about 1-2 months past maximum brightness. NOVA HERCULIS 1991 M. W. Feast, South African Astronomical Observatory, reports: "Spectra obtained at SAAO by T. L. Evans on Apr. 4 and 5 show the broad H-alpha emission (FWHM about 5000 km/s) is split into five main components with approximate velocities relative to line center 0, +/- 780, and +/- 1900 km/s. In each of the two pairs, the redshifted peak is about 0.7 the intensity of the blueshifted peak. This is consistent with absorption of the receding components by a dust shell 'McLaughlin effect' (cf. IAUC 5230). Note similarity to Nova Cyg 1978 (V1668 Cyg)." J. A. Mattei, AAVSO, forwards photoelectric observations by L. F. Snyder, Crystal City, NV, noting the presence of modulation with amplitude of 0.096 mag on Mar. 30 and 0.061 mag on Mar. 31 (the durations of the observations were not long enough to determine periodicity): Mar. 30.466 UT, V = 9.54; 30.473, 9.47; 30.489, 9.55; 30.496, 9.51; 31.488, 9.69; 31.491, 9.65; 31.524, 9.71. SS LEONIS MINORIS T. E. Harrison, Mt. Stromlo Observatory, reports: "B, V, R, and I CCD images, obtained with the Siding Spring 1.02-m telescope on Apr. 4.5 and 5.5 UT, of the field of SS LMi show an object at the position marked by Duerbeck (1987, Space Sci. Rev. 45, 177) for this supposed 1980 nova. The object is fairly red, at Cousins-Kron magnitude I about 17.7 (the object to the immediate north has I = 16.4). Advantage should be taken of this apparent brightening to determine the nature of this object." 1991 April 8 (5233) Daniel W. E. Green
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