Three Optical Transients detected by MASTER

ATel #5462; D. Denisenko, V. Vladimirov, S. Shurpakov, E. Gorbovskoy, V. Lipunov, N. Tiurina, P. Balanutsa, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov (Moscow State University, SAI), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova (Irkutsk State University), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of Pulkovo Observatory), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), P. Podvorotny, V. Shumkov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 11 Oct 2013; 14:59 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER OT J211458.15+582259.3 - new CV

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 21h 14m 58.15s +58d 22m 59.3s on 2013-10-09.51929 UT. The OT unfiltered magnitude is 17.0m (limit 19.2m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2011-05-22.70618 UT with unfiltered magnitude limit 18.9m.

There is nothing at this position in 1RXS, 2MASS, USNO-B1, GCVS and AAVSO VSX. This area of sky in Cepheus is not covered by SDSS and CRTS. Nothing is visible on the digitized Palomar plates and on their combination to m_lim~21.5. Color-combined (BRIR) DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J211458+582259-BRIR5x5.jpg

Based on the outburst amplitude (more than 4m) we suggest that MASTER OT J211458.15+582259.3 is a new cataclysmic variable (dwarf nova in outburst). Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/211458.15582259.3.png

MASTER OT J202506.02+582034.9 - flaring star

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 20h 25m 06.02s +58d 20m 34.9s on 2013-10-09.54867 UT. The OT unfiltered magnitude is 17.7m (limit 20.1m). The OT is seen in 3 images. The object has faded by 0.2m in 2.3 hours between the 180-sec exposures taken on 11:35 UT and 13:52 UT. There is no minor planet at this place. We have reference image without OT on 2011-08-17.66406 UT with unfiltered magnitude limit 19.5m.

The object at quiescence is identical to the star SDSS J202505.91+582035.4 with the magnitudes u=22.54 g=22.57 r=21.42 i=20.70 z=20.13. There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. Object was at minimum light on 9 DSS plates. This area of sky in Cygnus is not covered by CRTS.

Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/202506.02582034.9.png

MASTER OT J203220.79+660946.9 - new CV

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 20h 32m 20.79s +66d 09m 46.9s on 2013-10-09.58638 UT. The OT unfiltered magnitude is 18.1m (limit 19.3m). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2012-09-07.59267 UT with unfiltered magnitude limit 19.3m.

The object is not present in 1RXS, GALEX, USNO-B, 2MASS, GCVS and AAVSO VSX. This area of sky in Cepheus is not covered by SDSS and CRTS. There is a faint blue star at this position on the digitized Palomar plates. It is present in GSC 2.3.2 with the coordinates 20 32 20.843 +66 09 46.16 and jmag=21.39. Color-combined (BRIR) DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J203220+660946-BRIR5x5.jpg

Based on the blue color and amplitude of variability (more than 3m) we suggest that MASTER OT J203220.79+660946.9 is likely a new cataclysmic variable (dwarf nova in outburst). Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/203220.79660946.9.png

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