TITLE:   GCN CIRCULAR
NUMBER:  12691
SUBJECT: Possible detection of pre-trigger X-ray emission from GRB 111215A by MAXI/GSC
DATE:    11/12/16 09:38:44 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

N. Kawai, M. Morii (Tokyo Tech), H. Negoro (Nihon U.),  M. Serino (RIKEN),
K. Sugimori, R. Usui, T. Toizumi, Y. Aoki, S. Song (Tokyo Tech),
S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA),
T. Mihara, M. Sugizaki, S. Nakahira, T. Yamamoto, T. Sootome, M. Matsuoka (RIKEN), 
A. Yoshida, K. Yamaoka (AGU),
H. Tsunemi, M. Kimura, H. Kitayama (Osaka U.), 
M. Nakajima, F. Suwa, M. Asada, H. Sakakibara (Nihon U.), 
Y. Ueda, K. Hiroi, M. Shidatsu (Kyoto U.),
Y. Tsuboi, T. Matsumura, K. Yamazaki (Chuo U.)
M. Yamauchi, Y. Nishimura, T. Hanayama (Miyazaki U.) 
report on behalf of the MAXI team:

MAXI/GSC observed the position of GRB 111215A
(swift trigger=509717, Oates et al. GCN #12681)
at 13:12 and 14:44 on December 5, 2011 (UT), 
52 min before and 40 min after the trigger time.

The source was marginally detected as follows: 

Time    2-4 keV          4-10 keV
13:12   4 +-  7 mCrab  52 +- 19 mCrab
14:44  16 +- 10 mCrab  41 +- 19 mCrab

(uncertainties are 1-sigma statistical errors) 

If this detections are true it implies that the emission of GRB 111215A lasted
for more than 1.5 hours. Together with the long trigger timescale (320 s)
by Swift BAT, unusual for a GRB, we suggest that it may be a
non-GRB X-ray transient, such as an X-ray binary, AGN, or extragalactic TDE.

Multiwavelength follow-up observations are strongly encouraged.