MASTER possible optical counterpart of IceCube Alert 220220.60 / AMON NuEm-220220A

ATel #15231; O. A. Gress (Lomonosov MSU, ISU), V. M.Lipunov (Lomonosov MSU), N. M. Budnev (Irkutsk State University, API), K. Zhirkov, A. Kuznetsov, P. Balanutsa, E. Gorbovskoy, A. Chasovnikov, G. Antipov, D. Vlasenko, V. Senik, Ya. Kechin, V. Topolev, A. Gabovich(Lomonosov MSU, SAI, Physics Department), L. Carrasco, J. R.Valdes, V. Chavushyan, V. M.Patino Alvarez, J. Martinez, A. R.Corella, L. H.Rodriguez (INAOE, OAGH), C. Francile, R. Podesta, F. Podesta (OAFA), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov (Blagoveschensk Educational StateUniversity)
on 21 Feb 2022; 10:53 UT
Credential Certification: Vladimir Lipunov (lipunov2007@gmail.com)

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MASTER Global Robotic Net (Lipunov et al. 2010, Advances in Astronomy, v.2010, 30L) started IceCube 20220220.60/ AMON NuEm-220220A alert (a coincidence alert from the IceCube online neutrino selection + HAWC daily monitoring analysis GCN #31615, https://gcn.gsfc.nasa.gov/other/icecube_220220A.gcn3 )
optical observations 25 sec after notice time (618s after trigger time)
at 2022-02-20 14:29:55 UT at MASTER-Amur (Lipunov et al. GCN #31616) and observed it in MASTER-OAGH (Mexico), -SAAO (South Africa), -OAFA (Argentina), see cover map https://master.sai.msu.ru/site/master2/event.php?id=1889478

There is a blazar 5BZBJ1442+1200 (R.A.,Dec.(2000)=14 42 48.28 +12 00 40.28) 1.5 degrees from the center of current alert (Gress et al. GCN #31620).
There was IC-201014A in this region in history (https://gcn.gsfc.nasa.gov/other/icecube_201014A.gcn3 IC GCN #28624, MASTER GCN #28627 ).
Analysis of MASTER database (since 2004-04-10 22:28:32UT) and ATLAS light curve shows moderate dimming that started 10 days before the neutrino according to public ATLAS data (https://fallingstar-data.com/forcedphot/queue/169872/plot.pdf).
Due to this we suggest that 5BZBJ1442+1200 might be a source of NuEM-220220A even though it is largely outside the error-box.
The analysis will be continued.
Additional observations are planned.

MASTER Global Robotic Net