MASTER-SAAO: OT detected during Fermi 508270281 inspection

ATel #10065; T. Pogrosheva, P. Balanutsa, V. Lipunov (Lomonosov MSU), D. Buckley (SAAO), E. Gorbovskoy, N. Tiurina, O. Gress, V. Shumkov, A. Kuznetsov, V. Kornilov, V. Chazov (Lomonosov MSU), S. Potter (SAAO)
on 9 Feb 2017; 23:19 UT
Credential Certification: Nataly Tyurina (

Subjects: Optical, Request for Observations, Cataclysmic Variable, Gamma-Ray Burst, Transient, Variables

MASTER OT J113418.80-513313.5 discovery during Fermi GBM trigger 508270281 inspection
MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 11h 34m 18.80s -51d 33m 13.5s on 2017-02-08.93060 UT.
The OT unfiltered magnitude is 17.9m (mlim=18.4).
This OT was discovered during Fermi GBM 508270281 trigger (GRBtime=2017/02/08 18:11:16.40 UT ) The OT is seen in 4 images
2017-02-08 22:20:04.657
2017-02-08 22:21:37.16
2017-02-08 22:23:10.657
2017-02-08 22:29:43.246
We have reference image on 2015-01-11.90078 UT with unfiltered mlim= 19.1m.
There is GALEX source in 1" (accretion), so we suggest the dwarf nova outburst with ampl>4.1m (no known optical sources in VIZIER, it means as minimum POSS 22m limit in history)
In classic scenario this OT shouldn't be connected with GRB, spectral observations and deep photometry are required.
The discovery and reference images are available at:

MASTER Global Robotic Net