Two Optical Transients detected by MASTER

ATel #6300; V. Yecheistov, P. Balanutsa, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Vladimirov (Moscow State University, SAI), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov, A. Gabovich (Blagoveshchensk Educational University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress (Irkutsk State 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, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez, F. Podest (OAFA)
on 8 Jul 2014; 19:47 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J203421.90+120656.9 - new CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 20h 34m 21.90s +12d 06m 56.9s on 2014-07-04.56711 UT. The OT unfiltered magnitude is 17.4m (limit 17.7m). The OT is seen in 6 images. There is no minor planet at this place. We have reference image without OT on 2011-08-24.59733 UT with magnitude limit in V filter 18.6m.

The OT at quiescence is identical to the blue star USNO-B1.0 1021-0697450 (20 34 21.858 +12 06 57.43 pmRA=-10 pmDE=14 B1=20.32 R1=N/A B2=20.47 R2=20.80 I=N/A). Color-combined (BRIR) finder chart is uploaded to http://master.sai.msu.ru/static/OT/J203421+120657-BRIR5x5.jpg (2x zoom).

There is nothing at this position in 1RXS, 2MASS, GCVS and AAVSO VSX. Object is showing significant variability on the digitized Palomar plates. It has brightened on 1990-08-17 POSS-II red plate reaching the maximum light on 1990-08-20. The corresponding R magnitude in GSC 2.3.2 is 18.35. There are about 50 Palomar/NEAT images on 17 nights from 2000 June 25 to 2005 Sep. 04. The object was in outburst on three 2000 Aug. 07 images and at quiescence on other nights. This area of sky in Delphinus is not covered by SDSS and CRTS.

Based on the blue color, amplitude of variability and previous detections MASTER OT J203421.90+120656.9 is a new cataclysmic variable (dwarf nova in outburst). Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/203421.90120656.9.png

MASTER OT J011839.52+501813.4 - flaring red dwarf

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 01h 18m 39.52s +50d 18m 13.4s on 2014-07-07.70156 UT. The OT unfiltered magnitude is 17.3m (limit 18.8m). The OT is seen in 3 images. There is no minor planet at this place. We have reference image without OT on 2013-09-03.64177 UT with unfiltered magnitude limit 19.6m. The object has faded below 19.2m on the second triplet of images obtained 1 hour later, at 17:53:49 UT.

There is nothing at this position in any catalogs, including AAVSO VSX. This area of sky in Andromeda is not covered by SDSS and CSS. There is a faint red star on the digitized infrared Palomar plates at this place. Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J011839+501813-BRIR5x5.jpg (2x zoom).

Based on the red color and short flare duration, MASTER OT J011839.52+501813.4 is a new variable of UV Ceti type (flaring red dwarf). Follow up observations are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/011839.52501813.4.png

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