------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 2982 2014 Feb 19 15.49UT 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 ------------------------------------------------------------------- 500TH OPTICAL TRANSIENT DISCOVERED BY MASTER D. Denisenko et. al., Moscow State University reports on The Astronomer Telegram 5900 the discovery of MASTER OT J065921.17+102943.0, a possible cataclysmic variable, the 500th transient found by MASTER. MASTER-Amur auto-detection system discovered the OT source at: RA 06h 59m 21.17s DEC +10d 29' 43.0" (2000) on 2014 Feb 18.505UT. The OT, recorded on two images, has an unfiltered magnitude of 15.6 (limit 17.5m). They have a reference image without the OT on 2012 Sept 24.834UT with the unfiltered magnitude limit 18.3m. The OT at quiescence is identical to the blue star: USNO-B1.0 1004-0122737 (06 59 21.152 +10 29 43.43 pmRA=8 pmDE=-8 B1=19.35 R1=N/A B2=19.40 R2=17.19 I=18.75). A colour-combined (BRIR) finder chart has been uploaded to: http://master.sai.msu.ru/static/OT/J065921+102943-BRIR5x5.jpg (2x zoom). The object shows large variability between 1st and 2nd epoch Palomar plates. Comparison of POSS-I and POSS-II red plates is posted at: http://master.sai.msu.ru/static/OT/J065921+102943-POSS-Red.jpg There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. Based on the proper motion and amplitude of variability, MASTER OT J065921.17+102943.0 is most likely a cataclysmic variable. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/065921.17102943.0.png Guy M Hurst