- GCN Circular #18793
D. Itoh (Miyazaki U.), H. Negoro (Nihon U.),
H. Tomida, S. Nakahira, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Serino, 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, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (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, K. Furuya (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 00:43:52 UT on 2016 January 1.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (219.733 deg, -13.823 deg) = (14 38 55, -13 49 22) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.10 deg and 0.09 deg, respectively.
The roll angle of long axis from the north direction is 150.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 1543 +- 100 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:
(R.A., Dec) = (219.635 deg, -14.100 deg) = (14 38 32, -14 05 59) (J2000)
(R.A., Dec) = (219.486 deg, -13.957 deg) = (14 37 56, -13 57 24) (J2000)
(R.A., Dec) = (220.532 deg, -12.732 deg) = (14 42 07, -12 43 54) (J2000)
(R.A., Dec) = (220.677 deg, -12.878 deg) = (14 42 42, -12 52 39) (J2000)
There was no significant excess flux in the previous transit at 23:11 UT on 2015 December 31
with an upper limit of 20 mCrab for each.
- GCN Circular #18794
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 160101A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00051
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.
- GCN Circular #18795
L. Izzo (URoma/ICRA), V. D'Elia (ASDC), P. D'Avanzo (INAF-OAB), T.G.R.
Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), A.P. Beardmore
(U. Leicester), S.L. Gibson (U. Leicester), A. D'Ai (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 160101A (Itoh et al. GCN Circ. 18793) in a series of
observations tiled on the sky. The total exposure time is 1.7 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 512 s. The data were collected between T0+13.2 ks and T0+19.6 ks,
and are entirely in Photon Counting (PC) mode.
An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. The position of this source
is RA, Dec=219.6506, -13.8154 which is equivalent to:
RA (J2000): 14:38:36.14
Dec(J2000): -13:48:55.5
with an uncertainty of 3.7 arcsec (radius, 90% confidence). This
position is 4.8 arcmin from the MAXI position. The source has a mean
count rate of 3.9e-01 ct/sec; we cannot determine at the present time
whether it is fading.
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.5 (+0.5, -0.3). The
best-fitting absorption column is 1.20 (+2.17, -0.29) x 10^21 cm^-2,
consistent with the Galactic value of 9.1 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 4.6 x 10^-11 (5.1 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.20 (+2.17, -0.29) x 10^21 cm^-2
Galactic foreground: 9.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.5 (+0.5, -0.3)
The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00051/index_1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00051.
This circular is an official product of the Swift-XRT team.
- GCN Circular #18796
P Veres (UAH) reports on behalf of the Fermi GBM Team:
"At 00:43:53.61 UT on 01 January 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160101A (trigger 473301837 / 160101030)
which was also detected by MAXI/GSC (Itoh et al., GCN 18793)
and Swift/XRT (Izzo et al., GCN 18795).
The GBM on-ground location is consistent with the MAXI and Swift positions.
The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.
The GBM light curve consists of a single pulse
with a duration (T90) of about 4.7 s (50-300 keV).
The time-averaged spectrum from T0 to T0+7.3 s is
best fit by a Band function with Epeak = 135.0 +/- 5.2 keV,
alpha = -0.78 +/- 0.03, and beta = -2.26 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is
(1.682 +/- 0.024)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.9 s in the 10-1000 keV band
is 35.7 +/- 0.9 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #18797
M. H. Siegel (PSU) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began tiled observations of the field of the MAXI-detected
burst GRB 160101A (Itoh et al. GCN Circ. 18793) 13.2 ks after the burst. A
fading optical source consistent with position of the XRT source reported by
Izzo et al. (GCN Circ. 18795) is detected in the initial UVOT exposures in
the u filter.
The preliminary UVOT position is:
RA (J2000) = 14:38:36.12 = 219.65051 (deg.)
Dec (J2000) = -13:48:55.4 = -13.81539 (deg.)
with an estimated uncertainty of 0.58 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 13195 13397 198 17.55+-0.10
u 19592 19652 59 18.32+-0.32
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.09 in the direction of the
burst (Schlegel et al. 1998).
- GCN Circular #18805
T.Fujiwara, Y.Saito,T.Yoshii, Y.Tachibana, Y.Yano,
Y.Ono, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 160101A (D.Itoh et al., GCN Circular #18793) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2016-01-01 18:33:56 UT (~17.8 h after the burst). We cound not detect any optical point source in the error circle of the previously reported afterglow detected by Swift-XRT (L.Izzo et al., GCN Circular #18795) in all three bands.
Three sigma upper limits are listed below.
T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
---------------------------------------------------------------------------------------
18.9839 20:18:08 780 > 18.5 > 18.2 > 17.4
---------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration
- GCN Circular #18814
Y. Yamada, A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, K. Senuma,
M. Moriyama (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The long-duration GRB 160101A (Itoh et al. GCN Circ. 18793; Veres et al. GCN Circ. 18796)
triggered the CALET Gamma-Ray Burst Monitor (CGBM) at 00:43:54.04 UT on 1 January 2016.
The clear burst signal was detected by all instruments.
The light curve of the HXM shows a multiple peak structure starting at T0-2 sec and
ending at T0+8 sec. The T90 duration measured by the HXM1 data is
7.2 +- 1.3 sec (7-100 keV).
The CGBM data used in this analysis are provided by the Waseda CALET Operation Center
located at the Waseda University.
- GCN Circular #18838
S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration, intense GRB 160101A
(MAXI detection: Itoh et al., GCN Circ. 18793;
Fermi GBM detection: Veres, GCN Circ. 18796)
triggered Konus-Wind at T0=2631.931 s UT (00:43:51.931).
The burst light curve shows a single pulse
with a total duration of ~4.6 s.
The emission is seen up to ~5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160101_T02631/
As observed by Konus-Wind, the burst
had a fluence of 1.47(-0.17,+0.21)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.214 s,
of 1.18(-0.30,+0.35)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.19(-0.19,+0.25),
the high energy photon index beta = -2.86(-7.14,+0.38),
the peak energy 143(-19,+20) keV
(chi2 = 103/83 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.06(-0.23,+0.27)
and Ep = 612(-175,+321) keV (chi2 = 26/41 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta <-2.0
(chi2 = 26/40 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
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