MASTER-SAAO: 2 OT with fast variability.

ATel #8036; P. Balanutsa, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), N. Tyurina, V. Kornilov, A. Kuznetsov, I. Gorbunov, D. Vlasenko, V. Chazov (M. V. Lomonosov Moscow State University, SAI), S. Potter, M. Kotze (South African Astronomical Observatory), R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian (The Instituto de Astrofisica de Canarias),O. Gress, N. M. Budnev, K. Ivanov (Applied Physics Institute, Irkutsk State University), A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of the Pulkovo Observatory), V. Krushinski, I. Zalozhnykh (Ural Federal University), Yu. Sergienko, A. Gabovich, V. Yurkov (Blagoveschensk Educational State University)
on 10 Sep 2015; 19:35 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J194531.90-612009.5 discovery - possible fast optical transient, Ampl>3.7

MASTER-SAAO auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 19h 45m 31.90s -61d 20m 09.5s on 2015-09-08.89869 UT.
The OT unfiltered magnitude is 18.3m (the limit is19.7m).
There are 3 images with this OT on 2015-09-(08.908, 08.903, 08.898)UT with m_OT=18.3 (unfiltered, W=0.2B+0.8R corr.to USNO-B1). There are 3 images with previous outburst:
2015-07-13.971 with m_OT=17.9
2015-07-13.998 with m_OT=17.9
2015-07-14.003UT with m_OT=18.9.
There is no minor planet at this place. There is very faint source on blue and red POSS images (and CRTS observed this area without any source), so the Amplitude is more then 3.7m.

We have reference images without OT on 2015-05-20.95497 UT with 20.5 unfiltered magnitude limit, 2015-03-18.093 with m_lim=19.6, on 2015-02-16.104UT m_lim=18.5.

Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/194531.90-612009.5.png

MASTER OT J200952.34-683008.5 discovery - fast variability of blue GSC2.3 source with GALEX UV, optical Ampl>5m

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 20h 09m 52.34s -68d 30m 08.5s on 2015-09-09.04831 UT.
The OT unfiltered magnitude is 17.2m (limit 18.3m).
There are 3 images with m_OT:
2015-09-09.048UT 17.0
2015-09-09.052UT 16.6
2015-09-09.057UT 17.2

We have reference images without OT on 2015-02-15.107 with m_lim=19.9, 2015-03-29.977 with m_lim=19.8, 2015-06-21.808 with m_lim=19.3 There is only GSC2.3 star with blue j=21.92 and GALEX source. So we can suggest possible fast variability for the source with amplitude more then 5m.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/200952.34-683008.5.png

MASTER Global Robotic Net