GRB 160107A

S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 160107A
(MAXI/GSC detection: Nakagawa et al., GCN 18839
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 ;
Fermi GBM observation: Veres & Meegan, GCN 18844
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 ;
CALET Gamma-Ray Burst Monitor detection: Nakahira et al., GCN 18845
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 )
triggered Konus-Wind at T0=80440.646 s UT (22:20:40.646).

The burst light curve shows multiple, partly overlapped peaks
in the interval from ~T0-40 s to ~T0+110 s.
The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.48(-0.28,+0.54)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+25.232 s,
of 5.86(-1.22,+1.39)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+106.752 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 = -1.75(-0.16,+0.18),
and Ep = 131(-36,+85) keV (chi2 = 83/77 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.0 (chi2 = 82/76 dof).

The spectrum near the peak count rate
(measured from T0+24.832 to T0+33.024 s)
is best fit in the 20 keV - 3 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.52(-0.16,+0.18),
and Ep = 198(-43,+86) keV (chi2 = 49/68 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.1 (chi2 = 49/67 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160107_T80440/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

S. Nakahira (JAXA), A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, 
K. Senuma, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), 
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 160107A (MAXI/GSC, Nakagawa et al. GCN Circ. 18839
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 ; 
Fermi-GBM, Veres et al. GCN Circ. 18844
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 ) triggered the CALET Gamma-Ray Burst Monitor 
(CGBM) at 22:20:43.20 UT on 7 January 2016.  The clear burst signal was detected 
by all instruments.  

The light curve of the HXM shows at least three peaks starting and ending at 
T0 and T0+25 sec, T0+25 sec and T0+50 sec, and T0+52 sec and T0+80 sec, 
respectively.  The T90 duration measured by the SGM data is 116.0 s +/- 12.5 sec (40-1000 keV).  

The CGBM data used in this analysis are provided by the Waseda CALET Operation Center 
located at the Waseda University.

P Veres (UAH) and C Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 2016-01-07 22:20:41.50 UT on 7 January 2016, the Fermi Gamma-Ray
Burst Monitor
triggered and located GRB 160107A (trigger 473898045 / 160107931), which
was also detected by the MAXI/GSC (Nakagawa et al., GCN 18839
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 ).
The GBM on-ground location is consistent with the MAXI position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the best location is 62 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 114 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+110 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.79 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 54.5 +/- 2.6 keV.

The event fluence (10-1000 keV) in this time interval is
(3.63 +/- 0.06)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+27.7 s in the 10-1000 keV band
is 16.8 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 50.8 +/- 3.1 keV, alpha = -1.75 +/- 0.03 and beta = -2.47 +/- 0.14.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

Y. E. Nakagawa (JAXA),  H. Negoro (Nihon U.), M. Serino (RIKEN), S. Ueno, H. Tomida,
S. Nakahira, M. Ishikawa (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), Y. Kawakubo, A. Yoshida, T. Sakamoto, 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, D. Itoh, 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
22:19:56 UT on 2016 January 7. Assuming that the source flux was constant over the transit,
we obtain the source position at (R.A., Dec) = (299.670 deg, 6.413 deg) = (19 58 40, +06 24 46) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.20 deg and 0.15 deg,
respectively. The roll angle of long axis from the north direction is 151.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 366 +- 42 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:
(298.905 deg, 6.966 deg) = (19 55 37, +06 57 57) (J2000)
(299.190 deg, 7.260 deg) = (19 56 45, +07 15 36) (J2000)
(300.076 deg, 6.261 deg) = (20 00 18, +06 15 38) (J2000)
(299.789 deg, 5.968 deg) = (19 59 09, +05 58 03) (J2000)
There was no significant excess flux in the previous transit at 20:47 UT on 2016 January 7
and in the next transit at 23:52 UT on 2016 January 7 with an upper limit of 20 mCrab for each.

For more information: http://maxi.riken.jp/alert/novae/7394729601/7394729601.htm