MASTER: PSN in NGC4121 and CV outburst

ATel #12319; P. Balanutsa, V. Lipunov (Lomonosov MSU), D. Buckley (SAAO), E. Gorbovskoy, V. Kornilov, N. Tiurina, A. Kuznetsov, D. Vlasenko, V. Vladimirov, D. Zimnukhov, A. Chasovnikov (Lomonosov Moscow State University, SAI), N. Budnev, O. Gress (ISU), R. Rebolo Lopez, M. Serra-Ricart (IAC), R. Podesta, F. Podesta, C. Lopez, C. Francile (OAFA), H. Levato (SJNU), V. Senik, A. Tlatov, D. Dormidontov (Kislovodsk solar station of the Pulkovo observatory RAS), A. Gabovich, V. Yurkov, D. Kobtsev, Y. Sergienko (Blagoveshchensk Educational University), T. Pogrosheva, V. Shumkov (MASTER team members)
on 21 Dec 2018; 11:05 UT
Credential Certification: Nataly Tyurina (tiurina@sai.msu.ru)

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MASTER OT J120755.95+650647.8 discovery - PSN in NGC4121

MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )

discovered OT source at (RA, Dec) =12h 07m 55.95s +65d 06m 47.8s on 2018-12-20 19:32:41.182 UT.

The PSN unfiltered magnitude is 15.5m (limit 18.4m).

This PSN is seen in 4 images. There is no minor planet at this place. We have the nearest in time reference image without OT on 2018-08-12 21:16:05UT with 19.2 unfiltered magnitude limit.
Spectral observations are required.

The discovery and reference images are available at:

http://master.sai.msu.ru/static/OT/120755.95+650647.8.png

MASTER OT J233944.38-812648.4 detection - CV outburst, ampl>4.1m

MASTER-Kislovodsk auto-detection system discovered OT source at (RA, Dec) = 23h 39m 44.38s -81d 26m 48.4s on 2018-12-19 20:00:40.04 UT.

The OT unfiltered magnitude is 17.7m (19.3 limit).

This OT is seen in 3 images. There is no minor planet at this place.
We have the nearest in time reference image without OT on 2018-10-10 20:27:16UT with 20.1 unfiltered magnitude limit.
We have previous outburst on 2017-04-11 23:19:40.522UT (and 23:31:03.619UT, 23:43:42.244UT) with m_OT=18.0 (MASTER-SAAO)

There is GSC2.3.2 optical source with known only blue jmag=21.29; it means rmag=22m limit in history and more then 4.1m of current outburst amplitude (MASTER W=0.2B+0.8R calibrated by thousands USNO-B1 field stars at every 4 square degrees image).
Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/233944.38-812648.4.png

MASTER Global Robotic Net