GRB 161123A

C. Hanyu (Miyazaki U.), S. Nakahira (JAXA), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara (JAXA), 
Y. E. Nakagawa (JAMSTEC),
T. Mihara, M. Sugizaki, M. Serino, W. Iwakiri,  M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), 
N. Kawai, N.Isobe, S.Sugita, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), 
H. Tsunemi, R. Shomura (Osaka U.), 
M. Nakajima, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), 
Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), 
Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), 
M. Yamauchi, K. Furuya (Miyazaki U.), 
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:
 
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source 
at  03:05:58 UT on 2016 November 23.
The X-ray flux averaged over the scan was 149 +- 26 mCrab(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy,we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (32.229, -40.884) deg = (02 08 54, -40 53 02) (J2000)
(R.A., Dec) = (31.566, -40.860) deg = (02 06 15, -40 51 36) (J2000)
(R.A., Dec) = (32.268, -38.340) deg = (02 09 04, -38 20 24) (J2000)
(R.A., Dec) = (32.905, -38.394) deg = (02 11 37, -38 23 39) (J2000)
There was no significant excess flux in the previous transit at UT 01:33 
and in the next transit at 04:38 UT with an upper limit of 20 mCrab for each.

[GCN OPS NOTE(23nov16): Per author's request, the Subject was corrected
from 151123A to 161123A.]

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 161123A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00061

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), L.M. McCauley (PSU),
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), A.P. Beardmore (U.
Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 161123A (Hanyu et al. GCN Circ. 20203
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 ) in a series of
observations tiled on the sky. The total exposure time is 2.6 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 825 s. The data were collected between T0+21.8 ks and T0+28.0 ks,
and are entirely in Photon Counting (PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.02 to ~0.05 ct s^-1, corresponding to a 0.3-10 keV observed flux of
8.2e-13 to 1.9e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00061.

This circular is an official product of the Swift-XRT team.