TITLE: GCN CIRCULAR NUMBER: 40937 SUBJECT: LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations DATE: 25/07/04 06:49:21 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University kawakubo@phys.aoyama.ac.jp

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

We examined MAXI/GSC all-sky X-ray images (2-20 keV) after compact binary merger candidate S250704ab at 2025-07-04 04:30:48.040 UTC (GCN #40935).

At the trigger time of S250704ab, the high-voltage of MAXI/GSC was on, but the FOV was out of the 90% credible region of the bayestar skymap. 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 05:48:11 to 06:01:46 UTC (T0+4643 to T0+5458 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.

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