MASTER-OAFA: very bright, 7.6mag-amplitude OT

ATel #10307; T. Pogrosheva, V. Lipunov (Lomonosov MSU), R. Podesta (OAFA), H. Levato (ICATE), C. Francile, C. Lopez, F. Podesta (Observatorio Astronomico Felix Aguilar San Juan University), C. Saffe (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio), E. Gorbovskoy, N. Tiurina, P. Balanutsa, A. Kuznetsov, V. Kornilov, V. Chazov, D. Vlasenko, V. Vladimirov, O. Gress, I. Gorbunov, A. Krylov (Lomonosov Moscow State University, SAI), A. Gabovich (Blagoveschensk State University)
on 22 Apr 2017; 08:41 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J152915.84-344746.7 discovery - very bright (13.0 mag) high amplitude (>7.6mag) outburst

MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 15h 29m 15.84s -34d 47m 46.7s on 2017-04-20 05:37:30 UT. The OT unfiltered magnitude is 13.0m (mlim=18.9m). The OT is seen in 3 image (05:37:30, 05:48:11 ,05:58:57) with m_OT=13.0, it means not UVCet. There is unfiltered image on 2017-04-17 04:58:30UT with mlim=16.4, it means as minimum 3.4mag of amplitude less then during 3 days , it means not red giant, it means outburst.
There is no minor planet at this place.
We have reference images without OT on 2016-09-25.00861 UT with 18.9 unfiltered magnitude limit, and on 2016-06-08 21:10:23 with mlim=20.6.

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/152915.84-344746.7.png

MASTER OT J152635.52-215418.7 discovery - dwarf nova outburst, ampl>4.2m

MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 15h 26m 35.52s -21d 54m 18.7s on 2017-04-20.31506 UT.
The OT unfiltered magnitude is 17.8m (mlim=18.6m).
The OT is seen in 3 images. There is no minor planet at this place.
There is USNO-B1 star in 0.7" with known ast that time only blue B2=21.92 (and red limit 22mag. MASTER W=0.2B+0.8R using USNO-B1) , it means the Ampl of current outburst is more then 4.2mag . There is also GALEX source in 2.7" - accretion process, i.e.dwarf nova.
We have reference image without OT on 2016-07-11.07749 UT with 19.2 unfiltered magnitude limit
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/152635.52-215418.7.png

MASTER Global Robotic Net