THE ASTRONOMER Electronic Circular No 501 1991 Mar 28 20.32UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP, England. Telephone: (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 ------------------------------------------------------------------- NOVA HERCULIS 1991 Denis Buczynski, Conder Brow Observatory, reports a semi-precise position measured from the second confirmatory photograph taken on 1991 Mar 25.208UT (1 minute exposure, T-Max 400 film, 5" Zeiss Astrograph): RA 18h44m12.01s DEC +12 10'44.3"(1950). 7 AGK3 star reduction. The position is slightly uncertain due to heavy fogging of the film resulting from the dawn sky. It does, however, agree reasonably well with the result by Rob McNaught published on E500. It also suggests that star 1 (cf E500) listed by McNaught, could well be the pre-nova candidate. We have subsequently heard that Richard West, European Southern Observatory, has also proposed star 1 and provides a measure of this star from glass copies of the Palomar Sky Survey: RA 18h44m11.98s DEC +12 10'43.5"(1950). He reports that the blue and red magnitudes are about 19 and 17.5 respectively. A further measurement of star 1 has been reported by R.M.Humpreys et al of the University of Minnesota: RA 18h44m11.90s DEC +12 10'45.1"(1950). They report magnitudes for blue and red of 20.6 and 18.25. News of the discovery were passed to numerous professional astronomers around the world by Denis Buczynski and the Editor within hours of the first observation. J.Aycock et al, using the UK Infrared Telescope on Mauna Kea (report relayed by Alan Pickup, Edinburgh) obtained the following magnitudes: Mar 26.67UT: J=6.11 +/-0.07; H=6.08 +/-0.04; K=5.46 +/-0.08. Infrared spectra were also obtained with the 2.3-m telescope at Siding Spring following relay of E499 by Rob McNaught to T.E.Harrison. Fuller details will appear in 'The Astronomer' in due course. Mark Kidger relays that Carlos Martinez obtained an infrared spectrum with the Carlos Sanchez Telescope and Kidger's preliminary reductions are: Mar 26.1397 J=5.45, H=5.06, K=4.55 26.2679 J=5.41, H=5.08, K=4.62 (J is 1.26 microns, H=1.65 and K=2.20) Mark comments that the nova seems to be quite highly reddened and thus distant. He also mentions that the rate of decline is quite exceptional, perhaps similar to V1500 Cygni (=Nova Cygni 1975). Further visual estimates: 1991 Mar 25.80UT, 6.8 (McNaught, corrected from E500); 26.02UT, 7.3 (B.Granslo, Norway); 26.15, 7.2 (Russell Eberst, Scotland); 26.16, 7.2 (Daniel Verde, Gran Canaria); 26.37, 7.5 (John Bortle, USA); 26.404, 7.7 (Bortle); 26.81, 7.6 (McNaught); 27.09, 7.7 (Daniel Fischer, Koenigswinter, Germany); 27.18, 8.1 (George Alcock, co-discoverer); 27.36, 7.8 (A.Hale, USA); 27.79, 8.1 (McNaught); 28.10, 7.9 (Gary Poyner, Birmingham); 28.20, 8.5 (Bill Worraker, Didcot), Guy M Hurst