MASTER: bright OTs

ATel #8605; O. Gress, V. Vladimirov, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), P. Balanutsa, N. Tiurina, V. Kornilov, A. Kuznetsov, I. Gorbunov, D. Vlasenko, D. Kuvshinov, E. Popova (Lomonosov State University, SAI), S. Potter, M. Kotze (The South African Astronomical Observatory), N. Budnev, V. Poleschuk, K. Ivanov (Irkutsk State University, Applied Physics Institute)
on 29 Jan 2016; 10:41 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J145056.15-255526.9 discovery - dwarf nova outburst, ampl>4.3mag

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 14h 50m 56.15s -25d 55m 26.9s on 2016-01-27.02773 UT.
The OT unfiltered magnitude is 16.3m (limit 18.4m). There is no minor planet at this place.
Preliminary photometry is the following
Date, UT          Unfiltered m_OT     The number of images
2016-01-27 00:39:56.914-01:01:26.475    16.3    3
2016-01-28 00:48:56.138-00:56:19.67    16.6    6

We have reference images without OT on 2015-04-13.89786 UT with unfiltered magnitude limit 20.7m,
on 2015-05-24 20:17:12UT with m_lim=19.6,
on 2015-03-25 21:51:17 with m_lim=20.2,
on 2015-01-03 02:17:22 with m_lim=19.3
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/145056.15-255526.9.png

MASTER OT J180111.99-580705.6 discovery - dwarf nova outburst with ampl>4m

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 18h 01m 11.99s -58d 07m 05.6s on 2016-01-28.08697 UT.
The OT unfiltered magnitude is 14.9m (the limit is 18.2m).
The OT is seen in 8 images. There is no minor planet at this place.

We have reference images with unfiltered m_OT=18.0
and m_lim=20.6m on 2015-03-20.03369 UT ,
and with m_OT=18.4 on 2015-05-27 20:47:23.841,
m_OT=18.9 on 2015-10-21 19:17:12UT.

Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/180111.99-580705.6.png

MASTER OT J124204.36+075100.3 detection - possible dwarf nova outburst, ampl~3mag

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 12h 42m 04.36s +07d 51m 00.3s on 2016-01-09.88318 UT.
The OT unfiltered magnitude is 18.6m (the limit is 20.1m).
The OT is seen in 3 images. There is no minor planet at this place.

MASTER archive photometry of this star is the following
The Date,UT        Unfiltered m_OT       MASTER observatory
2012-05-15 19:58:56.977    19.6    MASTER-Kislovodsk
2014-01-03 23:45:36.606     18.8    MASTER-Kislovodsk
2016-01-05 03:43:38.854     18.6    MASTER-IAC
2016-01-11 03:05:20.618    19.1    MASTER-IAC
2011-03-28 23:05:10     NO_OT MASTER-Kislovodsk with m_limit=21.6 (2 images)
2012-05-17.64156UT   NO_OT   MASTER-Tunka with m_limit 19.5m.

There is no star in USNO catalogue, but there is a Sloan SDSS star with U=21.788,g=21.59, R=21.570, I=21.018. Also this star is in GUViCS(Ultraviolet Source Catalogs).So we suggest the dwarf nova outburst with amplitude about 3mag
Spectral observations are required.
The discovery and referenceimages are available at http://master.sai.msu.ru/static/OT/MASTEROTJ124204.36+075100.3.jpg

current outburst:
MASTER auto-detection system registered the current outburst of V0394 Aps (18 04 11.13 -71 59 47.5) 2016-01-27 01:47:53.859UT with unfiltered m=14.3m

MASTER Global Robotic Net