Four OTs discovered by MASTER

ATel #4131; P. Podvorotniy, P. Balanutsa, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, D. Zimnukhov, D. Gareeva (Moscow State University, SAI) V. Krushinsky, I. Zalozhnih, A. Popov (Ural State 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 the Pulkovo observatory RAS) V. Yurkov, Y. Sergienko, D. Varda, E. Sinyakov (Blagoveshchensk Educational University) V. Shumkov, S. Shurpakov (MASTER team members), H. Levato, C. Mallamaci, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (Observatorio Astronomico Felix Aguilar; OAFA)
on 28 May 2012; 16:27 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER OT J175846.44+001801.2 - new CV

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 17h 58m 46.44s +00d 18m 01.2s on 2012-05-24.92549 UT. The OT unfiltered magnitude is 18.1m (limit 19.0m).

The OT is seen in 5 images. There is no minor planet at this place. There is SDSS star J175846.41+001801.9 (rmag =21.7) at this position (offset is 0.9 arcsec). On the image taken on 2012-05-24.90146 UT the transient has unfiltered magnitude 18.9m.

MASTER-Kislovodsk observed this area of sky two days before the outburst, on 2012-05-22. Nine images with 180-sec exposure were obtained from 20:39:53 to 22:06:42 UT. Nothing is visible at the position of the OT J175846.44+001801.2 on any individual images (m_lim=18.4) as well as on the combination of them (m_lim=19.5).

The star is visible at the limit of the Blue DSS plates. Color-combined (BRIR) image of 5'x5' area centered at the OT J175846.44+001801.2 is available here: http://master.sai.msu.ru/static/OT/J1758+0018-BRIR5x5.jpg

Based on the outburst amplitude, rise time and fast variability as well as SDSS color (r-i=0.16) we conclude that MASTER OT J175846.44+001801.2 is a new cataclysmic variable (dwarf nova) in outburst. Follow up observations are requested.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/175846.44001801.2.png

MASTER OT J150210.65+230915.3 - PSN

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 15h 02m 10.65s +23d 09m 15.3s on 2012-05-24.86818 UT. The OT unfiltered magnitude is 19.2m (limit 20.2m). The OT is seen in 2 images. There is no minor planet at this place. There is SDSS galaxy J150210.47+230915.2 with 2.6 arcsec offset (rmag=21) . We have reference image without OT on 2010-03-21.01839 UT with unfiltered magnitude limit 20.5m. Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/150210.65230915.3.png

MASTER OT J145141.60+245745.7 - PSN

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 14h 51m 41.60s +24d 57m 45.7s on 2012-05-24.86818 UT. The OT unfiltered magnitude is 19.2m (limit 20.1m). There is SDSS galaxy J145141.63+245746.2 with 0.8 arcsec offset (rmag 19.8). The OT is seen in 2 images. There is no minor planet at this place. We have reference image without OT on 2010-03-20.98282 UT with unfiltered magnitude limit 20.3m. Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/145141.60245745.6.png

MASTER OT J192159.38+021255.9 - New Mira variable

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 19h 21m 59.38s +02d 12m 55.9s on 2012-05-22.98050 UT. The OT unfiltered magnitude is 13.8m (limit 17.3m).

The OT is seen in 11 images. There is no minor planet at this place. The star is not present in AAVSO VSX and GCVS. There is 2MASS object 19215929+0212559 (J=8.60, H=7.63, K=7.05) with 1.3 arcsec offset.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/192159.38021255.9.png

The variability of the star is obvious on DSS B and R plates. Animation of two DSS Red plates is presented at: http://master.sai.msu.ru/static/OT/J192159+021255-anim-DSS-R.gif

Based on 2MASS colors (J-K=1.65) and amplitude of variability on DSS plates we conclude that MASTER OT J192159.38+021255.9 is a new variable of Mira type.

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