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Three OTs detected by MASTER

ATel #4821; V. Yecheistov, S. Shurpakov, D. Denisenko, V. Lipunov, E. Gorbovskoy, P. Balanutsa, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, D. Zimnukhov (Moscow State University, SAI), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov, A. Punanova (Ural Federal University), K. Ivanov, S. Yazev, N. Budnev, E. Konstantinov, O. Chuvalaev, V. Poleshchuk, O. Gress, A. Frolova, (Irkutsk State University), A. Parkhomenko, A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk solar station of the Pulkovo observatory RAS), V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov (Blagoveshchensk Educational University), P. Podvorotny, V. Shumkov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 18 Feb 2013; 20:55 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Optical, Cataclysmic Variable, Transient

MASTER OT J062323.48+730744.0 - new bright CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 06h 23m 23.48s +73d 07m 44.0s on 2013-02-14.71662 UT. The OT unfiltered magnitude is 14.7m (limit 18.7m). The OT is seen in 2 images. We have reference image without OT on 2012-08-20.63529 UT with unfiltered magnitude limit 19.0m.

Previous outbursts were found in MASTER database:

 
Date, UT         Mag  Band  Observatory 
2011-11-07.728  14.96  W  MASTER-Kislovodsk 
2011-11-07.763  14.98  W  MASTER-Kislovodsk 
2012-03-24.646  14.42  V  MASTER-Amur 
2012-03-24.678  14.58  V  MASTER-Amur 
2012-09-30.680  14.57  W  MASTER-Amur 
2012-09-30.711  14.48  W  MASTER-Amur 
2013-01-08.606  14.90  W  MASTER-Amur

Star was in outbursts on several Palomar plates (1996 Jan. 18 blue, 1995 Feb. 07 infrared, 1997 Mar. 09 red and two 1983 Nov. 05 photovisual) and faint on 7 remaining DSS images. It is present in catalogs as USNO-A2.0 1575-02539528 (06 23 23.49 +73 07 42.8 R=18.3 B=18.5), USNO-B1.0 1631-0067280 (06 23 23.426 +73 07 43.05 B1=19.44 R1=18.51 B2=19.36 R2=17.48 I=15.30) and GSC 2.3.2 (06 23 23.525 +73 07 43.07 Fmag=17.32 jmag=19.52 Vmag=15.51 Nmag=15.23). There is an UV counterpart GALEX J062323.5+730742 (FUV=20.30+/-0.16, NUV=18.56+/-0.04).

Based on the amplitude of variability, blue color on POSS-I plates and in USNO-A2.0 as well as previous outbursts detection we conclude that MASTER OT J062323.48+730744.0 is a new dwarf nova of Z Cam (UGZ) or SU UMa (UGSU) type.

Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/062323.48730744.0.png

MASTER OT J184822.16+511218.8 - new bright CV

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 18h 48m 22.16s +51d 12m 18.8s on 2013-02-14.89402 UT. The OT unfiltered magnitude is 16.2m (limit 18.0m). The OT is seen in 2 images. We have reference image without OT on 2011-06-20.62994 UT with unfiltered magnitude limit 19.4m.

There is a star on Palomar plates USNO-B1.0 1412-0293818 with the following position: 18 48 22.161 +51 12 18.45 and magnitudes: B1=19.67 B2=20.72. It has also an UV counterpart GALEX J184822.2+511217 (FUV=21.67+/-0.33, NUV=21.00+/-0.23).

No previous outbursts were detected on 12 digitized Palomar plates. Based on amplitude of variability and blue color we conclude that MASTER OT J184822.16+511218.8 is a new cataclysmic variable (dwarf nova).

Follow up observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/184822.16511218.8.png

MASTER OT J233358.22+773951.2 - new CV?

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 23h 33m 58.22s +77d 39m 51.2s on 2013-02-15.51294 UT. The OT unfiltered magnitude is 17.2m (limit 18.2m). The OT is seen in 3 images. We have reference image without OT on 2012-08-25.72083 UT with unfiltered magnitude limit 18.5m.

There is nothing at this position on 14 digitized Palomar plates, as well as on their combination down to ~22.5m. Most likely MASTER OT J233358.22+773951.2 is a dwarf nova in Milky Way with outburst amplitude more than 5m. However, we note there is a galaxy 2MASX J23334968+7740170 (J=15.15+/-0.09, H=14.50+/-0.10, K=13.87+/-0.09) at 38" from the OT. Color-combined finder chart (sum of 3xBRIR DSS plates) of the OT is uploaded to http://master.sai.msu.ru/static/OT/J233358+773951-BRIR5x5.jpg

Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/233358.22773951.2.png

The position of all three objects is not covered by Palomar/NEAT, CRTS and SDSS. They are not present in 1RXS, 2MASS, GCVS and AAVSO VSX.

List of optical transients discovered by MASTER

Global MASTER Robotic Net