------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 2991 2014 Mar 24 13.21UT 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 ------------------------------------------------------------------- MASTER OT J192809.82+551616.5 P.Balanutsa, et. al., Moscow State University, reports on The Astronomer's Telegram 5994 that the MASTER-Amur auto-detection system has discovered OT source at: RA 19h 28m 09.82s DEC +55d 16' 16.5" on 2014 Mar 20.748UT. The Optical Transient (OT) unfiltered magnitude is 16.7m (limit 18.0m). The OT is seen in nine images. They have reference image without the OT on 2011 June 12.691UT with unfiltered magnitude limit 19.2m. The object was first detected on 2014 Mar 16.77837 UT at unfiltered magnitude 15.9 (limit 17.1m). There is nothing at this position on the digitised Palomar plates and on their combination to the limiting magnitude ~22.5. Colour-combined (BRIR) finder chart has been uploaded to http://master.sai.msu.ru/static/OT/J192809+551616-BRIR5x5.jpg The object is not present in any catalogues. This area of sky in Cygnus is not covered by SDSS, NEAT and CRTS. Based on the outburst amplitude of more than six magnitudes, MASTER OT J192809.82+551616.5 is most likely a dwarf nova or classical nova. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/192809.82551616.5.png A further report on ATEL 6005 by O. Gress (Irkutsk State University) and others indicates it might be a nova. Following the discovery of large amplitude optical transient MASTER OT J192809.82+551616.5 they have checked the archival data of MASTER network and obtained additional observations. Selected unfiltered magnitudes (including an upper limit 26 hours before the first positive detection) are listed in the table below. Observ. date, UT Mag. Observatory -------------------------------------------- 2014 Mar. 15.686 <16.6C MASTER-Kislovodsk 2014 Mar. 16.778 15.9C MASTER-Amur 2014 Mar. 20.749 16.7C MASTER-Amur 2014 Mar. 22.743 17.4C MASTER-Tunka 2014 Mar. 23.910 17.2C MASTER-Tunka -------------------------------------------- The object has shown a rapid fading followed by the plateau. Combined with the large amplitude such a behaviour is not typical for normal outbursts of dwarf novae. It could be a classical nova with a bright maximum missed on Mar. 17-19, or a precursor outburst of an extreme dwarf nova of WZ Sge or AM CVn type. Guy M Hurst