TITLE: GCN CIRCULAR NUMBER: 39253 SUBJECT: LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy DATE: 25/02/09 16:42:38 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs lipunov@xray.sai.msu.ru

V.Lipunov, E.Gorbovskoy, A.Kuznetsov, N.Tiurina, P.Balanutsa, I.Panchenko, A.Chasovnikov K.Zhirkov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, Ya.Kechin, V.Senik, V.Topolev (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. 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 Astrophysics Observatory)

MASTER600-Tunka robotic telescope located near Baykal lake (Applied Physics Institute, ISU, Lipunov, Korniov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591 pp. https://msupress.com/en/catalogue/books/book/astronomicheskie-robotizirovann...) was pointed to the FRB 20250206A error box (CHIME team, GCN 39216) 2.4 day after trigger time at 2025-02-08 11:37:22 (57.5h) at 2025-01-29 15:55:03 UT, with upper limit up to 19.4 mag on large zenit distance (80 degrees) and low temperature (<-30C degrees).

These observations were made like BOOTES-5 and 2.2m CAHA (A. J. Castro-Tirado et al., GCN 39247) in the background of the LIGO/Virgo/KAGRA S250206dm Grande campaign under Moon, which you can follow in our Web reports, with a detailed report coming soon. Real time updated cover map and discovered OT are available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=27337

The nearest bright galaxy is the spiral galaxy PGC1403722 (22h 34m 50.64s +12d 05m 46.7s) and could be a candidate host galaxy for the NS+BH pair that ejected from it several billion years ago (GCN 39220) with velocity several 100km/s (see the MASTER image http://observ.pereplet.ru/images/MASTER_FRB20250206A.jpg ). Its distance to Earth is well within the limits of CHIME and LVK S250206dm events.

The deep image is welcome.

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