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MASTER-SAAO: two dwarf outbursts

ATel #7860; O. Gress (ISU), P. Balanutsa, V. Lipunov, E. Gorbovskoy (Lomonosov MSU, SAI), D. Buckley (SAAO), N. Tiurina, A. Kuznetsov, V. Kornilov, V. Vladimirov, E. Popova, I. Gorbunov, D. Vlasenko, V. Chazov, D. Kuvshinov (Lomonosov Moscow State University, Sternberg Astronomical Institute), S. Potter, M. Kotze (South African Astronomical Observatory), N. M.Budnev, K. Ivanov (Applied Physics Institute, Irkutsk State University), R. Rebolo, M. Serra-Ricart, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), A. Tlatov, D. Dormidontov, V. Senik, A. V. Parhomenko (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 31 Jul 2015; 19:33 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

Subjects: Optical, Request for Observations, Cataclysmic Variable, Transient, Variables

MASTER OT J012608.84-234636.5 discovery - possible dwarf nova outburst, Ampl>2m

MASTER-SAAO auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 01h 26m 08.84s -23d 46m 36.5s on 2015-07-26.06086 UT.

The OT unfiltered magnitude is 19.2m (the limit is 20.8m).There are 8 images with OT in MASTER-SAAO database. There is no minor planet at this place.

We have reference image without OT on 2015-01-11.82681 UT with unfiltered magnitude limit 20.2m. There is USNO B1 star with B1=19.84,B2=21.23, R1=20.27,R2=23.24. This OT is a GALEX source with FUV=21.134. So we can suggest dwarf nova outburst with amplitude more then 2m.

Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/012608.84-234636.5.png

MASTER OT J001400.25-561735.0 - bright dwarf outburst with amplitude more then 3.7m

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 00h 14m 00.25s -56d 17m 35.0s on 2015-07-25.85398 UT.

The OT unfiltered magnitude is 15.3m (the limit is 18.8m). There are 7 images with this bright OT. There is no minor planet at this place.

We have reference images with quiet OT on 2014-12-28.883UT with unfiltered (0.2B+0.8R USNO-B1) m_OT=18.4, on on 2015-01-11.842UT with m_OT=18.8, 2015-02-17.775UT with m_OT=19.0, on 2015-04-15.1344UT with m_OT=18.5, on 2015-06-09.11640 UT with m_OT=18.9m. There was a previous possible burst with V=16.3 in CRTS archive. There is a star with B=18.9 and R=18.45(GSC 2.2).
So we can suggest the dwarf nova outburst with amplitude more then 3.7m .
Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/001400.25-561735.0.png

List of Optical Transients discovered by MASTER

MASTER Global Robotic Net