TITLE:   GCN CIRCULAR
NUMBER:  38748
SUBJECT: LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
DATE:    25/01/01 02:29:35 GMT
FROM:    Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>

M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu, H. Nishikawa, Y. Kondo (AGU),
H. Negoro, M. Nakajima, K. Takagi (Nihon U.),
N. Kawai, T. Mihara, (RIKEN)
report on behalf of the MAXI team:

We examined MAXI/GSC all-sky X-ray images (2-20 keV)
after compact binary merger candidate S241231du at 2024-12-31 13:16:46.194 UTC.

At the trigger time of S241231du, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered 4% of the 90% credible region
of the bayestar sky map, in which we found no significant new X-ray source.
The first one-orbit (92 min) scan observation with GSC after the event covered 90%
of the 90% credible region of the bayestar skymap from 13:16:46 to 14:48:44 UTC (T0+0 to T0+5518 sec).

No significant new source was found in the region in the one-orbit scan observation.
A typical 1-sigma averaged upper limit obtained in one scan observation
is 20 mCrab at 2-20 keV.

If you require information about X-ray flux by MAXI/GSC at specific coordinates,
please contact the submitter of this circular by email.