MASTER-Net: 2 optical transients

ATel #7576; E. Popova, O. Gress, V. Lipunov, E. Gorbovskoy (Lomonosov MSU), D. Buckley (SAAO), S. Antipin, P. Balanutsa, N. Tiurina, V. Kornilov, A. Kuznetsov, V. Chazov (Lomonosov Moscow State University, SAI), S. Potter, A. Kniazev, M. Kotze (The South African Astronomical Observatory), N. Budnev, K. Ivanov, S. Yazev, V. Poleshchuk (Irkutsk State University), A. Tlatov, D. Dormidontov, V. Senik, A. Parkhomenko, (Kislovodsk solar station of the Pulkovo observatory RAS), V. Krushinsky, I. Zalozhnih, A. Popov, A. Bourdanov (Ural Federal University), Yu. Sergienko, V. Yurkov, A. Gabovich (Blagoveschensk State Educational University), V. Shumkov, S. Shurpakov (MASTER-Team)
on 29 May 2015; 08:04 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J004202.43+481308.4 discovery - cataclismic variable with Ampl>2.6

MASTER-Kislovodsk auto-detection system ( Lipunov et al., Advances in Astronomy, MASTER Global Robotic Net, 2010 ) discovered OT source at (RA, Dec) = 00h 42m 02.43s +48d 13m 08.4s on 2015-05-26.93644 UT. The OT unfiltered magnitude is 18.0m (the limit is 18.7m).

There are 3 images with OT, the same mag. There is no minor planet at this place.

We have 70 reference images in MASTER-Kislovodsk database without OT since 2010-11-04 15:25:24 with m_lim from up to 20.6, for ex., on 2012-09-16.90605 UT with unfiltered magnitude limit 20.6m. There is a GSC star with red F_mag=20.14 and blue Jmag=21.36 and Vmag=17.

Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/004202.43481308.4_1.png

MASTER OT J205739.86-201349.5 discovery - possible Dwarf Nova outburst with Ampl>3.5m

MASTER-SAAO auto-detection system discovered OT source at (RA, Dec) = 20h 57m 39.86s -20d 13m 49.5s on 2015-05-26.98164 UT. The OT unfiltered magnitude is 18.5m (limit 19.9m).

There are 3 images with OT. There is no minor planet at this place.
We have reference image without OT on 2015-05-26.97238 UT with unfiltered magnitude limit 19.6m. There is no any known source in VIZIER database inside 5". So we can suggest dwarf nova outburst with amplitude more then 3.5m.

Spectral observations are required.

The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/205739.86-201349.5.png

MASTER Global Robotic Net