TITLE:   GCN CIRCULAR
NUMBER:  39713
SUBJECT: IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
DATE:    25/03/14 02:36:51 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

K. Labzina,  K.Zhirkov, V.Lipunov, E.Gorbovskoy, A.Kuznetsov, G.Antipov, D.Vlasenko,
A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, V.Topolev, Ya.Kechin, V.Senik (Lomonosov MSU),
O.Gress, N.Budnev, O.Ershova (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
D.Buckley (SAAO),
A.Sosnovskij (Crao RAS),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro AstrophysicsObservatory)


MASTER-OAFA robotic telescope  (Global MASTER-Net: Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) 
located in Argentina (OAFA observatory of San Juan National University)
started IceCube-250309A (IC GCN#39631) alert error-box (trigger No 1288692,14h 03m 12.24s , -10d 26m 24.0s, R=0.51)
9 sec after notice time (109 sec after trigger time) at 2025-03-09 07:37:54 UT, with upper limit up to  21.3 mag. (Lipunov et al.GCN#39630)

MASTER cover map:
https://master.sai.msu.ru/site/master2/observ.php?id=2805613

We analyzed MASTER archive images since 2013 of possible sources, that can be related with this event.
There is blazar J140105.33-091631.6 inside 3 sigma https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=&-out.add=_r&-out.add=_RAJ%2C_DEJ&-sort=_r&-to=&-out.max=20&-meta.ucd=2&-meta.foot=1&-c=210.27220833333+-9.2754444444444&-c.rs=5
We detected its decay and  brightening up to usual state after 10 hours of IC event trigger time.

MASTER archive light curve from 2013 year is available at
   http://observ.pereplet.ru/IC/MASTER_IC250309A.jpg

This, we report observation of an Zhirkov effect, discovered earlier
(The Astrophysic Jornal Letters, 896, L19, 2020 https://ui.adsabs.harvard.edu/abs/2020ApJ...896L..19L/abstract ).