TITLE:   GCN CIRCULAR
NUMBER:  34088
SUBJECT: LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
DATE:    23/06/27 08:50:43 GMT
FROM:    Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>

N. Kawai (RIKEN), H. Negoro, M. Nakajima (Nihon U.),
T. Mihara (RIKEN),
S. Sugita, M. Serino, H. Hiramatsu, H. Nishikawa (AGU),
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 S230627c at 2023-06-27 01:53:37.819 UTC (GCN 34086).

At the trigger time of S230627c, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered 5% 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 64%
of the 90% credible region of the bayestar skymap from 01:53:37 to 03:25:36 UTC (T0+0 to T0+5519 sec).

No significant new source was found in the region in the one-orbit scan observation.
Because the 90% credible region of this event was observed by degraded camera,
a typical 1-sigma averaged upper limit obtained in one scan observation
is 140 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.