MASTER: PSN in PGC421615 and 3 dwarf nova outbursts

ATel #8065; O. Gress, P. Balanutsa, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), R. Rebolo (IAC), N. Tyurina, V. Kornilov, A. Kuznetsov, I. Gorbunov, D. Vlasenko, V. Chazov (M. V. Lomonosov Moscow State University, SAI), S. Potter, M. Kotze (South African Astronomical Observatory), M. Serra-Ricart, N. Lodieu, G. Israelian (The Instituto de Astrofisica de Canarias), N. M. Budnev, K. Ivanov (Applied Physics Institute, Irkutsk State University), A. Tlatov, D. Dormidontov, V. Senik (Kislovodsk Solar Station of the Pulkovo Observatory), Yu. Sergienko, A. Gabovich, V. Yurkov (Blagoveschensk Educational State University), V. Krushinski, I. Zalozhnykh (Ural Federal University)
on 17 Sep 2015; 23:02 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J040938.68-541316.9 discovery - possible SN (17.3m) in PGC421615 (0.9"W,3.6"N)

MASTER-SAAO auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 04h 09m 38.68s -54d 13m 16.9s on 2015-09-16.87912 UT.
The OT unfiltered magnitude is 17.3m (the limit is 17.8m).
The OT is seen in 5 images. There is no minor planet at this place. We have reference image without OT on 2015-02-14.89772 UT with 20.0 unfiltered magnitude limit.
This PSN is in 0.9"W and 3.6"N from the center of galaxy PGC421615 (Btot=18.4m).
Spectral observations are required.
The discovery and reference images are http://master.sai.msu.ru/static/OT/040938.68-541316.9.png

MASTER OT J202411.65-172512.5 discovery - dwarf nova outburst with Ampl>2.7m

MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 20h 24m 11.65s -17d 25m 12.5s on 2015-09-17.86176 UT.
The OT unfiltered magnitude is 17.9m (the limit is 19.0m).
The OT is seen in 4 images. There is no minor planet at this place. We have reference images without OT on 2015-06-10.16132 UT with unfiltered magnitude limit 19.2m(MASTER-IAC), 2015-04-28 00:08:26 with m_lim=20.6 (MASTER-SAAO), 2014-11-23 14:55:07UT with m_lim=20.0(MASTER-Kislovodsk database). So we can suggest the dwarf nova outburst with Ampl>2.7m.
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/202411.65-172512.5.png

MASTER OT J181609.38+311641.9 discovery -new dwarf nova outburst, Ampl>3.4m

MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 18h 16m 09.38s +31d 16m 41.9s on 2015-09-13.89443 UT.
The OT unfiltered magnitude is 18.6m (limit 19.8m).
There are 4 images with OT. There is no minor planet at this place. We have reference images without OT on 2015-06-10.10177 UT with unfiltered magnitude limit 19.5m in MASTER-IAC database, on 2010-05-15 21:19:08 with m_lim=20.0 (MASTER-Kislovodsk), on 2015-01-28 22:32:26 UT with m_lim=19.8(MASTER-Tunka).
There is no any source in VIZIER database and no any faint sources in Palomar images, so, taking into account the POSS limit (22m), we can suggest the amplitude>3.4m of this possible dwarf nova outburst.
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/MASTEROTJ181609.38311641.9.png

MASTER OT J233023.63+744535.6 detection - dwarf nova outburst, Ampl>3.4m
MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 23h 30m 23.63s +74d 45m 35.6s on 2015-09-12.69332 UT.
The OT unfiltered magnitude is 16.5m (the limit is 19.3m).
There are 3 images with OT (12.701, 12.697, 12.693UT). There is no minor planet at this place. We have reference images without OT on 2013-10-13.623UT with unfiltered magnitude limit 18.9m.

We have previous outbursts of this possible dwarf nova in MASTER database:
Date,UT // OT unfiltered magnitude // Observatory
2012-11-23.533 17.1 MASTER-Tunka database
2010-09-26.909 16.6 MASTER-Kislovodsk
2014-10-03.833 18.8 MASTER-Kislovodsk
2014-04-04.521 17.5 MASTER-Amur

There is an USNO-B1 star with B2=20.11,R2=19.79, so we suggest the dwarf nova outbursts with Ampl>3.4m
The discovery and reference images are available at http://observ.pereplet.ru/images/MASTEROTJ233023.63744535.6.png

Spectral observations are required.

MASTER Global Robotic Net