TITLE:   GCN CIRCULAR
NUMBER:  31948
SUBJECT: IceCube-220425A: MASTER: flaring blazar  TXS 1742-078 as the possible neutrino source candidate 
DATE:    22/04/25 15:44:17 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko, A.Kuznetsov, 
N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov, V.Topolev,Ya.Kechin, 
Yu.Tselik, K.Minkina
(Lomonosov Moscow State University, SAI, Physics Department),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, 
A.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

N.M.Budnev, O.Gress,
(ISU,API),

C.Francile, R. Podesta, C.Lopez, F. Podesta
(Observatorio Astronomico Felix Aguilar OAFA),

D.A.H.Buckley
(SAAO),

R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),

V.Senik, A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov
(Blagoveschensk Educational State University)


MASTER-OAGH was the first telescope of MASTER-NET to observe IC-220425's
error-box at 2022-04-25 06:35:11 UTC, 13813 sec after the trigger
(Lipunov et al., GCN #31946).

We report on the detection of a flaring blazar TXS 1742-078 (RA=266.3629 
Dec=-7.8844).

IC-220425A is a track-like event with an estimated energy of 600 TeV and 
signalness of 17%. It was detected at 2022-04-25 02:44:58 UTC 
and is  centred at RA=268.24 (+1.98, -1.66 deg, 90% PSF containment), 
Dec=-10.73  (+1.71, -1.48 deg, 90% PSF containment) J2000(GCN #31944).

The first image of TXS 1742-078 was obtained at 2022:04-25 06:36:32 UTC. 
It is located 3.4 deg away from the center of error-box.
Based on our photometry, the blazar is currently experiencing a flaring 
episode (W=17.3+/-0.1, no correction for extinction), compared to its 
quiscence state (W=19.2+/-0.3). Judging from ATLAS observations(Smith et 
al, PASP 132, 2020)(https://fallingstar-data.com/forcedphot/queue/195704/plot.pdf) it is 
31944the brightest flare since 2017.

Interestingly enough, after the correction for galactic 
extinction(Schlafly and Finkbeiner, 2011) (A_V=3.18), magnitude of TXS 
1742-078 (W=14.1+/-0.1) is close to that of TXS 0506+056 during IC-170922A 
(W=14.3, no correction for extinction).

Judging from these facts, we highly encourage multiwavelength observations 
to determine whether or not this blazar is a source of IC-220425A

The observation and reduction will continue.
The message may be cited.