H. Negoro, M. Nakajima (Nihon U.),
T. Mihara, N. Kawai (RIKEN),
S. Sugita, M. Serino, H. Hiramatsu, H. Nishikawa, Y. Kondo (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 S230917af at 2023-09-17 10:04:17 UTC .
At the trigger time of S230917af, the high-voltage of MAXI/GSC was on,
but the FOV was out of the 90% credible region of the cwb skymap.
The first one-orbit (92 min) scan observation with GSC after the event covered 100%
of the 90% credible region of the cwb skymap from 10:41:56 to 10:53:01 UTC (T0+2259 to T0+2924 sec).
There was a low significance burst-like X-ray event at
(R.A., Dec) = (333.784 deg, 39.435 deg) = (22 15 08, +39 26 06) (J2000)
with a statistical 90% C.L. error region of ~0.6 deg.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The sources region was observed around 10:50:13 UTC.
The X-ray flux averaged over the scan was 48 +- 13 mCrab
(4.0-10.0keV, 1 sigma error).
If you require information about X-ray flux by MAXI/GSC at specific coordinates,
please contact the submitter of this circular by email.