Аннотация: MASTER OT J063429.91-300200.2 discovery - bright high amplitude (>6.4m) dwarf nova outburst
MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 06h 34m 29.91s -30d 02m 00.2s on 2016-04-21.79961 UT.
The OT unfiltered magnitude is 14.9m (limit 18.0m).
The OT is seen in 2 images. There is no minor planet at this place.
We have reference image without OT on 2015-02-19.95449 UT with unfiltered magnitude limit 19.7m.
There is GSC 2.3.2 star with only blue 21.29mag, so we suggest the amplitude of outburst more then 6.4m
. There is GALEX source in 2.8".
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/063429.91-300200.2.png
MASTER OT J154801.52-292515.0 discovery - bright dwarf nova outburst with ampl>4.6
MASTER-IAC auto-detection system discovered OT source at (RA, Dec) = 15h 48m 01.52s -29d 25m 15.0s on 2016-04-19.13267 UT.
The OT unfiltered magnitude is 15.4m (limit 17.6m).
The OT is seen in 6 images. We have reference image without OT on 2016-03-18 01:58:39UT with m_lim=20.1 in MASTER-SAAO database and on 2015-07-06.93472 UT with unfiltered m_lim=18.8m in MASTER-IAC database.
There is previous outburst on 2015-01-21 01:15:56.294 with m_OT=16.6 in MASTER-SAAO database, and reference image without OT on 2015-06-19 21:06:18 with m_lim=20.1.
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/154801.52-292515.0.png
MASTER OT J202523.12-532407.9 discovery - bright dwarf nova outburst, Ampl>4.3m
MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 20h 25m 23.12s -53d 24m 07.9s on 2016-04-19.98108 UT.
The OT unfiltered magnitude is 16.3m (limit 18.8m).
The OT is seen in 5 images. There is no minor planet at this place.
We have reference unfiltered images without OT on
2015-10-11.78266UT m_lim=20.9m
2015-11-30 19:51:59UT m_lim=19.2
2015-11-23 20:11:49UT m_lim=18.7
2015-10-11 18:47:02UT m_lim=20.9
There is USNO-B1 star with R1=17.58m, B2=21.41. There is GALEX source, so there is accretion to the white dwarf.
We checked colleagues' lists and found, that ASAS detected this source as PSN on 2015-10-24.06 with possibility to be CV in ATEL #8214.
MASTER discovery and reference images are available at http://master.sai.msu.ru/static/OT/202523.12-532407.9.png
MASTER OT J133352.93-375140.8 discovery - optical transient, outburst's ampl>2.4m, possibly dwarf nova
MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 13h 33m 52.93s -37d 51m 40.8s on 2016-04-14.91277 UT.
The OT unfiltered magnitude is 18.7m (limit 19.6m).
The OT is seen in 5 images.We have reference image without OT on 2015-02-23.02387 UT with unfiltered magnitude limit 21.1m.
Spectral observations are required.
The discovery and reference images are available at http://master.sai.msu.ru/static/OT/133352.93-375140.8.png