GRB 151205C

GRB 151205C: MAXI/GSC detection

M. Nakajima, H. Negoro (Nihon U.), M. Serino (RIKEN), T. Sakamoto (AGU),
S. Nakahira, S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN),
N. Kawai, M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech),
A. Yoshida, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, R. Imatani (Osaka U.),
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:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at UT 2015/12/05 23:54:06.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (329.725 deg, 77.705 deg) = (21 58 54, +77 42 17) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.24 deg and 0.2 deg, respectively.
The roll angle of long axis from the north direction is 102.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 152 +- 24 mCrab
(4-10keV, 1 sigma error).

Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(326.621 deg, 76.996 deg) = (21 46 29, +76 59 46) (J2000)
(328.465 deg, 76.767 deg) = (21 53 51, +76 46 02) (J2000)
(333.174 deg, 78.383 deg) = (22 12 41, +78 23 00) (J2000)
(331.143 deg, 78.636 deg) = (22 04 34, +78 38 08) (J2000)

There was no significant excess flux in the previous transit at UT 22:21
and in the next transit at 12/6 01:26 UT with an upper limit of 20 mCrab for each.

Detection Information:
http://maxi.riken.jp/alert/novae/7361767105/7361767105.htm

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 151205C. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00049

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. Melandri, P. D'Avanzo (INAF-OAB) A. D'Ai (INAF-IASFPA), J.A. Kennea
(PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), K.L. Page (U.
Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A.
Maselli  (INAF-IASFPA) 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 151205C (Nakajima et al. GCN Circ. 18666
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 ) in a series of
observations tiled on the sky. The total exposure time is 2.5 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 790 s. The data were collected between T0+11.1 ks and T0+22.8 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 ~0.03 ct s^-1, corresponding to a 0.3-10 keV observed flux of
7.6e-13 to 1.1e-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_GRB00049.

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

Yuki Kikuchi (U. of Tokyo), Masaomi Tanaka (NAOJ), Ryou Ohsawa,
Makoto Ichiki, Shigeyuki Sako, Tomoki Morokuma, Mamoru Doi (U. of Tokyo),
Nozomu Tominaga (Konan U.), Motoko Serino (RIKEN), Akihiro Suzuki,
Keiichi Maeda (Kyoto U.), and Takanori Sakamoto (AGU) report:

We performed optical non-filter imaging observations for
the MAXI-detected burst GRB 151205C (Nakajima et al. GCN Circ. 18666
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 )
with a prototype model camera of Tomo-e Gozen (Tomo-e PM).
Tomo-e Gozen is a wide-field optical imaging camera
with 84 1kx2k CMOS sensors on the focal plane of
the 1.05-m Kiso Schmidt telescope (Sako et al. in preparation,
http://www.ioa.s.u-tokyo.ac.jp/tomoe/).
The prototype model camera has 8 CMOS sensors along the RA direction
with spatial gaps of 25 arcmin between the adjacent chips.
The field-of-view of each chip is 39.7 arcmin (RA) x 22.4 arcmin (Dec).
Thanks to the low dark current of the sensors in room
temperature, we operate the CMOS sensors without coolers
which enables us to make a light-weight camera system.
By using 1 of 8 chips of Tomo-e PM,
multiple regions which cover in total 95% of the localization area 
(with the following central coordinates) have been observed.

 RA       | Dec       | Obs. time        | t-t0*  | Exptime |
 (J2000)  | (J2000)   | (UT)             | (days) | (sec)   |
 22:00:34 | +77:39:51 | 2015 Dec 6 14:08 | 0.59   | 150     |
 21:58:01 | +77:41:46 | 2015 Dec 6 14:25 | 0.60   | 150     |
 22:05:23 | +78:26:45 | 2015 Dec 7 09:12 | 1.39   | 180     |
 22:02:51 | +78:06:14 | 2015 Dec 7 09:15 | 1.39   | 180     |
 21:55:36 | +77:28:11 | 2015 Dec 7 09:22 | 1.39   | 180     |
 21:58:37 | +77:45:37 | 2015 Dec 7 09:26 | 1.40   | 180     |
 22:08:11 | +78:19:44 | 2015 Dec 8 14:22 | 2.60   | 150     |
 22:04:56 | +78:03:18 | 2015 Dec 8 14:25 | 2.61   | 144     |
 22:02:25 | +77:42:13 | 2015 Dec 8 14:29 | 2.61   | 144     |
 21:58:14 | +77:22:13 | 2015 Dec 8 14:31 | 2.61   | 180     |
 21:55:13 | +77:04:13 | 2015 Dec 8 14:34 | 2.61   | 180     |
* time after the burst

We performed image subtraction using
PTF R-band data taken on 2011 Jul 17 as references
(obtained through IPAC, Law et al. 2009, PASP, 121, 1395;
Laher et al. 2014, PASP, 126, 674).
No new transient objects have been found within these fields.
The limiting magnitudes of our data are about 20 mag
(calibrated with USNO UCAC3 catalog, Zacharias et al. 2010, AJ, 139, 2184).