THE ASTRONOMER Electronic Circular No 640 1992 May 26 19.17UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074 Telex: 9312111261 Answerback: TA G JANET BOXES: GMH at UK.AC.CAM.ASTRONOMY.STARLINK or GUYH at UK.AC.SUSSEX.CLUSTER TELECOM GOLD: 10074:MIK2885 PRESTEL 256471074 ------------------------------------------------------------------- PROBABLE NOVA IN SCORPIUS Paul Camilleri, Cobram, Victoria, reports his discovery of what appears to be a nova at R.A. = 17h03m.9, Decl. = -43 12' (1950). The following magnitude estimates are by Camilleri unless otherwise noted, and all are photovisual except for those on May 24 (which are visual): Apr. 28.600 UT, [12; May 22.492, 8.2; 23.511, 8.3; 24.371, 8.3 (P. Williams, Heathcote, N.S.W.); 24.425, 8.4. IAUC 5526 COMET BRADFIELD (1992i) No observations of this comet have been reported to TA since the discovery announcement on E637 and we understand that the Central Bureau has also received no further precise positions. David Herald has provided the following predictions based on elements derived from visual positions: T = 1992 May 26.76 TT Peri. = 299.84 Node = 157.32 2000.0 q = 0.5747 AU Incl. = 157.53 1992 TT R. A. (2000) Decl. Delta r Elong. Phase m1 May 26 5 59.80 + 5 00.9 0.617 0.575 30.6 116.3 7.5 28 6 23.93 + 7 39.7 0.678 0.575 32.7 107.7 7.8 30 6 43.38 + 9 53.7 0.745 0.579 34.3 99.1 8.0 June 1 6 58.95 +11 46.5 0.817 0.587 35.3 90.9 8.2 3 7 11.43 +13 22.3 0.893 0.598 35.8 83.3 8.5 5 7 21.49 +14 44.5 0.969 0.611 35.8 76.2 8.8 7 7 29.66 +15 55.9 1.046 0.628 35.4 69.6 9.1 IAUC 5524 NOVA CYGNI 1992 G. M. Hurst, The Astronomer, reports that inspection of 0.5-day means of visual data of Nova Cyg 1992 taken by The Astronomer Group are suggestive of an about 2.5- or 5-day periodicity post-maximum. Subsequent periodicity analysis by M. Kidger (Instituto de Astrofisica de Canarias), using the Jurkevich method, of > 400 visual data points in The Astronomer Group archive supports a 4.7- day period with regular minima of amplitude 0.3 mag, and Kidger notes: "There is also some evidence of a possible intermediate shallow secondary minimum. Analysis of all available V-band photo- metric data from IAUCs, The Astronomer Group, and Agrupacion Astro- nomica de Tenerife shows regular oscillations in the light curve until late April. Periodicity analysis gives a best period of 4.6 +/- 0.2 days. There are insufficient data to define the mean light curve form, but the photometric amplitude agrees with that from the visual data. These oscillations are similar to those of V1668 Cyg = N Cyg 1978 (Campolonghi et al. 1980, A.Ap. 85, L4), but are considerably slower. No obvious colour variations are seen with this period. Since t3, which was 47 days, the oscillations have apparently disappeared." IAUC 5526 Guy M Hurst