TITLE:   GCN CIRCULAR
NUMBER:  19013
SUBJECT: LIGO/Virgo G184098: MAXI/GSC search for an X-ray counterpart of GW150914
DATE:    16/02/16 12:31:05 GMT
FROM:    Nobuyuki Kawai at Tokyo Tech  <nkawai@phys.titech.ac.jp>

M. Serino (RIKEN), H. Negoro (Nihon U.), N. Kawai (Tokyo Tech)
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, 
M. Matsuoka (RIKEN), 
M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech),
A. Yoshida, T. Sakamoto, H. Ohtsuki Y. Kawakubo (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.),
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.),
Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (Chuo U.),
M. Yamauchi, D. Itoh, (Miyazaki U.)
K. Yamaoka (Nagoya U.),
M. Morii (ISM)

report on behalf of the MAXI team:

We reexamined the MAXI/GSC all-sky X-ray images (2-20 keV) obtained
in the orbits preceding and following the gravitational wave event
LIGO/Virgo G184098 at 2015-09-14T09:50:45 UTC 
(GW150914; Abbott et al. 2016).

In each of the 92-min orbits, MAXI/GSC scanned more than 90% 
of the localization (90% confidence) regions in the bayestar skymap.
No significant new source was found in these scans.
The elapsed time of each scan since the trigger time is: 
 -5147 ~  -4614 s (preceding the event)
  +409 ~   +937 s (scan in the orbit immediately after the event)
 +5964 ~  +6492 s (second orbit after the event)
+11530 ~ +12050 s (third orbit after the event)
+17082 ~ +17593 s (fourth orbit after the event)

The 3-sigma upper limit of each scan for the X-ray flux is
about 1x10^-9 erg/s/cm^2 in 2-20 keV. 

[GCN OPS NOTE(16feb16):  Per author's request, the "LIGO/Virgo G184098:"
was added to the Subject line and the contact address was changed.]