THE ASTRONOMER Electronic Circular No 429 1990 July 11 19.31UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074 Telex: 94082518 Answerback: TAGUY Microlink: MAG60138 JANET:GMH @ UK.AC.CAM.ASTRONOMY.STARLINK or GUYH@UK.AC.SUSSEX.CLUSTER --------------------------------------------------------------------- BZ URSAE MAJORIS This probable SU UMa-type dwarf nova, located at RA 08h49.9m DEC +58 00'(1950) has been observed in outburst by P.Schmeer of Bischmisheim, Federal Republic of Germany and confirmed by Gary Poyner of Birmingham: 1990 July 9.936UT, 12.2 (Schmeer); 10.96, 12.4 (Poyner). R.Claudi et al, Padova and Asiago Observatories, reported an orbital period of 1.62hr on IAUC 4975 which would place it amongst the SU UMa sub-group. 1990 MF (cf E427) The following orbital elements, by J. F. Chandler, Center for Astrophysics, are from optical observations June 22-July 3 and highly precise radar data obtained by S. Ostro at Arecibo Ionospheric Observatory on July 4 and 5. In attempting to represent the optical data, it should be noted that these elements are offset to the FK5 equinox: Epoch = 1990 June 18.0 ET T = 1990 Aug. 9.2824 ET Peri. = 112.7385 e = 0.456068 Node = 210.9790 1950.0 q = 0.950103 AU Incl. = 1.8705 a = 1.746730 AU n = 0.4269385 P = 2.309 years 1990 ET R.A. (1950) Decl. Delta r V July 11 15 38.6 +71 50.9 12 15 00.4 +79 58.6 0.034 1.007 14.3 13 11 52 +86 10.3 14 6 28.9 +83 15.2 0.037 0.999 14.8 15 5 27.2 +77 22.0 16 5 07.2 +71 57.2 0.042 0.992 15.3 17 4 57.60 +67 12.5 18 4 52.13 +63 05.6 0.049 0.986 15.7 IAUC 5050 VY AQUARII Further selected estimates (cf E427): 1990 July 4.008, 10.7 (Schmeer); 7.045, 11.0 (Schmeer); 10.090, 11.3 (Schmeer). Patrick comments that this is an SU UMa-type undergoing a superoutburst, the last such event was in 1988 Sept although a normal outburst occurred 1989 August. CH URSAE MAJORIS P.Schmeer reports: June 26.942UT, [13.2; July 10.95, 12.6. Guy M Hurst