Supernova 1987A in the Large Magellanic Cloud

W. Kunkel and B. Madore, Las Campanas Observatory, report the discovery by Ian Shelton, University of Toronto Las Campanas Station, of a mag 5 object, ostensibly a supernova, in the Large Magellanic Cloud at R.A. = 5h35m.4, Decl. = -69 16' (equinox 1987.2), 18' west and 10' south of 30 Dor and possibly involved with the association NGC 2044. The discovery was made around Feb. 24.23 UT on a 3-hr exposure with a 0.25-m astrograph beginning on Feb. 24.06, and the object had evidently brightened by at least about 8 mag since the previous night. An independent suspected sighting was made visually by Oscar Duhalde, also at Las Campanas, around Feb. 24.2. The object had brightened to about mag 4.5 by Feb. 24.33. F. M. Bateson, Royal Astronomical Society of New Zealand, informs us that the object was discovered independently by Albert Jones, Nelson, on Feb. 24.37 UT (position R.A. = 5h35m.8, Decl. = -69 18', equinox 1950.0) at mag 6.5-7.0 (in clouds); he estimated mv = 5.1 on Feb. 24.46. B. Moreno and S. Walker, Auckland Observatory, obtained V = 4.81, B-V = +0.085, U-B = -0.836 on Feb. 24.454 UT. R. H. McNaught, Siding Spring Observatory, communicates the following visual magnitude estimates by G. Garradd (G) and himself (M): Feb. 24.455, 4.8 (M); 24.472, 4.8 (M); 24.635, 4.4 (G); 24.679, 4.5 (M); 24.717, 4.4 (M). McNaught obtained the following precise position with the University of Aston Hewitt Satellite Schmidt camera: R.A. = 5h35m50s.22, Decl. = -69 17'59".2 (equinox 1950.0, uncertainty 2"). The object appears on films from the previous night: Feb. 23.443, 6.0; 23.445, 6.2. He also notes the position of a blue star, of mv about 12 and not obviously variable during the past century (through Feb. 22.4): R.A. = 5h35m50s.12, Decl. = -69 17'58".0 (equinox 1950.0; x = 15447, y = 9261 in the Harvard LMC system). Films by Garradd confirm that the field was identical down to mag 14.5 on Jan. 24 and Feb. 22. B. Warner, University of Texas, reports that a spectroscopic observation by J. Menzies on Feb. 24.9 UT with the 1.9-m reflector at the South African Astronomical Observatory shows the 615-nm dip, indicating that the object may be a supernova of type I.