------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 2733 2011 Apr 22 14.18UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK Backup: gmh@wdcc1.bnsc.rl.ac.uk WORLD WIDE WEB http://www.theastronomer.org ------------------------------------------------------------------- HBC 722: FU-ORI STAR In NGC 7000 Further to the announcement by E. Semkov on TA E-Circular 2667 issued on 2010 August 20 and in The Astronomer's Telegram 2801, a further report by Semkov has appeared on this star in The Astronomer's Telegram 3296. We continue the photometric monitoring of the FUor star HBC 722 in the field of NGC 7000/IC 5070. The recent BVRI photometric data were obtained with the telescopes of the National Astronomical Observatory Rozhen (Bulgaria). The outburst of HBC 722 was detected during the summer of 2010 and up to September 2010 the star brightness increased by 4.7 mag (V). Since October 2010, a slow fading was observed and up to February 2011 the star brightness decreased by 1.1 mag (V). The calculated fading by Kospal et al. (2011, A&A, 527, 133) is 0.25 mag/month (I) for the same period. Our photometric observations obtained in the period 2011 Feb 6 - Apr 7 suggested that the fading is much slower then before. Our estimations give the values as follow: For I and R the fading is approximately 0.05 mag/month, for V - 0.07 mag/month, and for B - 0.11 mag/month. The light curve break happens in the late January/beginning of February. This change in the rate of decreased brightness indicates that the outburst of HBC 722 will continue much longer than the early estimates. We consider this result as one further confirmation of the FUor nature of the observed outburst. SUPERNOVA 2011an IN UGC 4139 = PSN J07592442+1625082 (CSS) 2011an Mar 1.19 07 59 24.42 +16 25 08.2 18.4 11.6"E, 8.5"S G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA) reports that a spectrum on 2011 Mar 5UT shows it to be a type-IIn supernova then near maximum light. SUPERNOVA 2011ao IN IC 2973 = PSN J11535103+3321463 (Kroes) 2011ao Mar 3.43 11 53 51.03 +33 21 16.3 17.1 2.9"E, 9.9"S The peculiar type-Ic supernova 1991A also appeared in IC 2973. D. K. Sahu et. al., Indian Institute of Astrophysics, Bangalore, report that a spectrum obtained on Mar. 5.99UT with the Indian Astronomical Observatory's 2-m Himalayan Chandra Telescope showed it to be normal type-Ia supernova then about a week before maximum light. Guy Hurst reports the object has brightened substantially since discovery and that an unfiltered image on 2011 April 12.12UT with the Bradford Robotic Telescope using a V sequence gave 15.2. SUPERNOVA 2011aq IN NGC 1056 = PSN J02424814+2834258 (LOSS) 2011aq Jan 24.20 02 42 48.14 +28 34 25.8 18.0 2.9"W, 0.9"S J. M. Silverman et. al., University of California, Berkeley, report that a CCD spectrum on Mar. 9UT with the 10-m Keck I telescope shows it is a type-II supernova with an age of about 1.5 months. SUPERNOVA 2011ar IN UGC 2509 = PSN J03032521+0429399 (LOSS) 2011ar Jan 27.20 03 03 25.21 +04 29 39.9 19.0 15.1"E, 8.9"N J. M. Silverman reports a spectrum of Mar 9UT indicates it to be type-II supernova. Guy M Hurst