MASTER-OAFA: optical transient

ATel #11140; T. Pogrosheva, V. Vladimirov, V. Lipunov, V. Kornilov (Lomonosov MSU), R. Podesta (OAFA), H. Levato (ICATE), E. Gorbovskoy, V. Shumkov, N. Tiurina, P. Balanutsa, A. Kuznetsov, V. Chazov, D. Vlasenko, O. Gress, I. Gorbunov, A. Krylov (Lomonosov Moscow State University, SAI), C. Lopez, F. Podesta, C. Francile (Observatorio Astronomico Felix Aguilar San Juan University), C. Saffe (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio), A. Gabovich (Blagoveschensk State Pedagogical University), V. Senik (Lomonosov MSU)
on 7 Jan 2018; 23:26 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J091047.21-622754.5 discovery - new OT, possib.dwarf nova, ampl>4.5mag

MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net",Advances in Astronomy, 2010, 30L )
discovered OT source at (RA, Dec) = discovered OT source at (RA, Dec) = 09h 10m 47.21s -62d 27m 54.5s on 2018-01-03.32081 UT.
The OT unfiltered magnitude is 17.5m (mlim=18.4m).
The OT is seen in 6 images. There is no minor planet at this place.
We have reference image without OT on 2016-12-29.22309 UT with unfiltered mlim=19.3m.
There is no known sources in VIZIER database, it means 22m POSS limit in history and more then 4.5m of current outburst amplitude
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/091047.21-622754.5.png

MASTER OT J152804.66-673720.4 detection - dwarf nova? ampl>2.7mag

MASTER-OAFA auto-detection system discovered OT source at (RA, Dec) = 15h 28m 04.66s -67d 37m 20.4s on 2018-01-04.34900 UT.
The OT unfiltered magnitude is 16.8m (mlim=17.0m).
The OT is seen in 3 images. There is no minor planet at this place.
We have reference image without OT on 2017-06-19.06255 UT with unfiltered mlim=18.2m, and marginally seen OT at 2016-03-09 21:15:13UT m_OT << mlim=19.5, that gives amplitude of current outburst more then .

We have previous outburst in 2016 2016-07-22 02:30:10UT 16.4 (2 images)
2016-07-23 02:37:32UT 16.0 (2 images)
2016-07-25 02:49:27UT 17.2 (2 images)
2016-07-30 02:15:32UT no OT mlim=18.1

There is GSC2.3.2 star with B=17.04,R=17.97 in 1992.568,also IGSL source (Smart et al., 2013) with B_(GSC2.3)=19.9 (1992.5699) in VIZIER database
Spectral observations, deep photometry are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/152804.66-673720.4.png

MASTER OT J103830.90-640119.4 detection - OT, ampl>4m

MASTER-OAFA auto-detection system discovered OT source at (RA, Dec) = 10h 38m 30.90s -64d 01m 19.4s on 2017-12-28.11745 UT.
The OT unfiltered magnitude is 16.7m (mlim=17.6m). The OT is seen in 3 images. There is no minor planet at this place.
We have reference images without OT on 2017-12-08.17044 UT with unfiltered mlim=17.5m(nearest in time), on 2015-01-05 00:44:41 with mlim=18.1.
There is USNO-B1 star with B2=19.44 (and R2<22m limit?), and R1=17.3 (and B1<22m limit?), that gives the ampl of current outburst more then 4m.
Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/103830.90-640119.4.png

MASTER Global Robotic Net