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MASTER: 2 short optical transients

ATel #10049; P. Balanutsa, V. Lipunov (Lomonosov MSU), R. Rebolo, M. Serra-Ricart (IAC),D. Buckley(SAAO), E. Gorbovskoy, N. Tiurina, A. Kuznetsov, E. Popova, O. Gress, V. Kornilov, V. Vladimirov (Lomonosov Moscow State University, SAI)
on 4 Feb 2017; 11:32 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

Subjects: Optical, Transient

MASTER OT J133017.28+780951.8 discovery - short very bright OT

MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 13h 30m 17.28s +78d 09m 51.8s on 2017-02-02.96362 UT.
The OT is seen on 3 images with the following m_OT:
2017-02-02 23:03:55.905 18.57
2017-02-02 23:05:36.496 14.48
2017-02-02 23:07:37.042 14.92
We have reference image without OT on 2016-06-10.89789 UT with unfiltered magnitude limit 19.1m.
Spectral observations are required.

This OT was detected during Fermi trigger 507702864 inspection ( https://gcn.gsfc.nasa.gov/other/507702864.fermi GRB_TIME: 17/02/02 04:34:19.80 UT ), but can't be the counterpart from just this GRB (from delay between GRB time and inspection time),but it may be "orphan" - from another GRB, that jet wasn't registered by Earth's space gamma-detectors.
We can't use UVCet scenarion, because The UVCet usually has the longer time for beginning of flare, not 4mag for 1.5min, it is too quickly. The second reason not to be UVCet is high amplitude of this source - more then 7.5mag.
The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/133017.28780951.8.png

MASTER OT J134513.91-551738.0 detection MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 13h 45m 13.91s -55d 17m 38.0s on 2017-02-03.01818 UT.
The OT unfiltered magnitude is 16.4m (mlim=18.4).
The OT is seen in 1 image. There is no minor planet at this place. There is no any sources in NORAD database inside.
The optical unfiltere limits for flare are
2017-02-03 00:40:06UT mlim=18.5
2017-02-03 00:29:50UT m_OT=16.4
2017-02-03 00:26:11UT m_lim=18.5
We have reference image on 2016-09-12.74417 UT with unfiltered mlim= 18.4m.
Spectral observations are required.
The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/134513.91-551738.0.png