GRB 140221A

GRB 140221A: MAXI/GSC detection

Y. Morooka (Miyazaki U.), H. Negoro (Nihon U.), Y. Ogawa (Miyazaki U.), 
S. Ueno, H. Tomida, S. Nakahira, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, M. Serino,  J. Sugimoto, T. Takagi, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, R. Usui, T. Yoshii, Y. Tachibana (Tokyo Tech), 
A. Yoshida, T. Sakamoto, Y. Nakano, Y. Kawakubo, A. Kawagoe,H. Ohtsuki (AGU), 
H. Tsunemi, M. Sasaki (Osaka U.), 
M. Nakajima, H. Sakakibara, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.), 
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.), 
Y. Tsuboi, M. Higa (Chuo U.), 
M. Yamauchi, K. Yoshidome, H. Yamada (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 UT 2014-02-21 T07:12:50.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (107.447 deg, -17.336 deg) = (07 09 47, -17 20 09) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.40 deg and 0.34 deg, respectively.
The roll angle of the long axis from the north direction is 146.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment  radius).
The X-ray flux averaged over the scan was 68 +- 18 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 5:40.

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 140221A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00025

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; and 2009, MNRAS, 397, 1177).

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

M.C. Stroh (PSU), J. Kennea (PSU), D. Burrows (PSU), K. Page (U. Leicester) and P. A. Evans (U. Leicester) report on behalf of the Swift Team:

Swift-XRT has observed the error circle of the MAXI GRB 140221A in a
series of observations tiled on the sky. The total exposure time is 4.9
ks spread over 7 fields; the maximum exposure within the sky observed
was 1.4 ks. The observations started 10.9 ks after the MAXI trigger.
Within these data there are 2 objects detected, both of which are catalogued in
X-rays.

Source 1: 
Catalogued source: 1SXPS J071032.3-171853
RA:  107.63465 = 07h 10m 32.32s (J2000)
Dec:  -17.31486 = -17d 18' 53.5" (J2000)
Err: 10.0 arcsec (radius, 90% confidence)
This is an enhanced position, determined by using UVOT field stars to
determine the astrometry.Exposure time: 536 s
Online products:
http://www.swift.ac.uk/xrt_products/TILED_GRB00025/index_1.php

Source 2:
Catalogued source: 1SXPS J071108.3-171031
RA:  107.78605 = 07h 11m 8.65s (J2000)
Dec:  -17.17431 = -17d 10' 27.5" (J2000)
Err: 10.0 arcsec (radius, 90% confidence)
Exposure time: 817 s
Online products:
http://www.swift.ac.uk/xrt_products/TILED_GRB00025/index_2.php

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