GCN Circular 34871

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

We examined MAXI/GSC all-sky X-ray images (2-20 keV)
after compact binary merger candidate S231021az at 2023-10-21 23:37:57 UTC .

At the trigger time of S231021az, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered 1% 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 86%
of the 90% credible region of the bayestar skymap from 23:37:57 to 01:09:53 UTC (T0+0 to T0+5516 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.