THE ASTRONOMER Electronic Circular No 645 1992 June 15 20.00UT 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 ------------------------------------------------------------------- SUPERNOVA 1992aa IN NGC 6464 Jean Mueller reports her discovery of a supernova in NGC 6464 (R.A. = 17h45m.2, Decl. = +60 55', equinox 1950.0), found on a plate taken by J. D. Mendenhall and herself on May 10 UT with the 1.2-m Oschin Telescope in the course of the second Palomar Sky Survey. SN 1992aa was then at red mag about 18 and is located 11" south of the galaxy nucleus, on a spiral arm. A confirming spectrogram was obtained on June 3 by M. Ashby and J. R. Houck with the 5-m Hale Telescope (+ double spectrograph), the spectrum showing the broad H-alpha and H-beta indicative of a supernova. IAUC 5534 SUPERNOVA 1992ab IN NGC 6389 Mueller also reports her discovery of a supernova in NGC 6389 (R.A. = 17h30m.5, Decl. = +16 26', equinox 1950.0), found on a plate taken by C. Brewer and J. D. Mendenhall on June 1 UT with the 1.2-m Oschin Telescope in the course of the second Palomar Sky Survey. SN 1992ab was then at red mag about 17 and is located 80" east and 20" south of the galaxy nucleus. A confirming spectrogram was obtained on June 4 by Ashby and Houck with the 5-m Hale Telescope (+ double spectrograph). NOVA CYGNI 1992 In response to requests from professional astronomers using the MERLIN array, Denis Buczynski, Conder Brow Observatory, has measured a precise position for the nova as follows: RA 20h30m31.7s DEC +52 37'50.5"(2000). This is significantly different from the original position by Skiff where declination end figures were 52.9" (cf E611) and it is therefore not clear whether the proposed pre-nova candidate is correct. Using the data by Buczynski and another precise position measured with the Carlsberg AMC at La Palma (end figures 31.674s; 50.90"), the nova has been detected at 6-cm radio emission using MERLIN on May 9. There has recently been significant scatter in the visual observations of this nova. Pending a detailed analysis, it is essential that those observers who have previously reported magnitudes only, please re-send their results with the full estimate showing clearly all comparisons used. If for any reason the TA sequence was not used, please give details of the chart and sequence which form the basis of the results. AH HERCULIS Gary Poyner, Birmingham, reports that this UG star is again fading after one of the longest standstills on record. The star remained near magnitude 12.5 from 1992 April 15 until June 11.968 when it was observed at 13.6. Guy M Hurst