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Three OTs of different types detected by MASTER

ATel #5030; P. Balanutsa, D. Denisenko, V. Lipunov, E. Gorbovskoy, N. Tiurina, V. Kornilov, A. Belinski, N. Shatskiy, V. Chazov, A. Kuznetsov, V. Yecheistov, 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, S. Shurpakov (MASTER team members), H. Levato, C. Saffe (ICATE), C. Mallamaci, C. Lopez and F. Podest (OAFA)
on 30 Apr 2013; 15:14 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

Subjects: Infra-Red, Optical, Cataclysmic Variable, Transient, Variables

MASTER OT J183012.04+093342.6 - slow red variable

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 18h 30m 12.04s +09d 33m 42.6s on 2013-04-22.73760 UT. The OT unfiltered magnitude is 11.8m (limit 16.9m). The OT is seen in 9 images. We have unfiltered reference image with the object at 14.5m on 2012-11-07.435 UT (limit 16.6m).

There is a red star at this position on Palomar plates USNO-B1.0 0995-0363063 (R1=17.37, R2=14.81, I=11.11). It shows obvious variability between 1991 May 21 and 1993 July 15 POSS-II red plates. The OT is identical to the infrared source IRAS 18278+0931 and 2MASS 18301210+0933425 (J=7.02+/-0.03, H=5.475+/-0.03, K=4.52+/-0.02). It is present in the Optical/near-IR atlas of OH/IR stars (Jimenez-Esteban et al., 2005) and in OH observations of Arecibo OH/IR stars (Lewis, 1997).

Object is not present in GCVS and AAVSO VSX. However, NSVS data show the slow variability fading from 12.9 to 13.9m in 340 days: NSVS 10972342 light curve.

Follow up observations are desirable. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/183012.04093342.6.png

MASTER OT J011613.54+640832.0 - new R CrB variable

MASTER-Amur auto-detection system discovered OT source at (RA, Dec) = 01h 16m 13.54s +64d 08m 32.0s on 2013-04-26.69067 UT. The OT unfiltered magnitude is 14.1m (limit 16.9m). The OT is seen in 2 images. We have reference image without OT on 2012-04-18.558 UT with unfiltered m_lim=16.2.

The object is identical to IRAS 01129+6352 = 2MASS 01161363+6408319 (J=11.79+/-0.02, H=9.16+/-0.02, K=7.01+/-0.02). It is included in the Catalogue enriched with R CrB stars (Tisserand, 2012) based on near-IR (2MASS) and mid-infrared (WISE) characteristics. However, no variability was mentioned before.

The star is present in USNO-B catalog as USNO-B1.0 1541-0038015 (RA=01 16 13.593, Dec=+64 08 32.12, R1=18.30, R2=17.14, I=15.56). Color-combined DSS finder chart is uploaded to http://master.sai.msu.ru/static/OT/J011613+640832-BRIR5x5.jpg (5'x5' FOV). The object was at low state during Palomar survey showing little variability between POSS-I and POSS-II plates.

On the other hand, the object was likely at a high state in 1999-2000 during NSVS (ROTSE-I) observations. The light curve of NSVS 1689547 has the variable nearly constant with median ROTSE Mag 13.407, Mag Scatter 0.095 and Median Error 0.074. Such a behavior is consistent with R CrB nature of this object, as suggested by Tisserand.

Follow up photometry and spectroscopy are encouraged. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/011613.54640832.0.png

MASTER OT J200748.53+592237.8 - CV or PSN

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 20h 07m 48.53s +59d 22m 37.8s on 2013-04-27.82855 UT. The OT unfiltered magnitude is 16.8m (limit 18.5m). The OT is seen in 2 images. We have reference image without OT on 2011-10-22.711 UT with unfiltered m_lim=20.1. Object was confirmed at 17.1m on two unfiltered MASTER-Amur images of 2013-04-29.777 and 29.780 UT.

The OT is located 1" W and 2" N from the faint (r=22) red object listed as GALAXY in SDSS DR7: SDSS J200748.64+592235.2, but as a STAR in SDSS DR8: SDSS J200748.64+592235.1. However, a faint blue object is visible on color-combined SDSS image within 1" of the OT. It can be a dwarf nova with outburst amplitude more than 6m.

Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/200748.53592237.8.png

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