GRB 180113C

P. Veres (UAH), C. Meegan (UAH) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:

"At 10:02:05.41 UT on 13 January 2008, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180113C (trigger 537530530 / 180113418).

The on-ground calculated location, using the GBM trigger
data, is RA = 174.6, DEC = -64.7 (J2000 degrees,
equivalent to 11 h 39 m, -64 d 44 '), with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

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 GBM ground location is 63 degrees.

The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 24.6 s (50-300 keV).
The time-averaged spectrum from T0+3.1 s to T0+34.8 s is
best fit by a Band function with Epeak = 307 +/- 4 keV,
alpha = -0.68 +/- 0.01, and beta = -2.09 +/- 0.01.

The event fluence (10-1000 keV) in this time interval is
(6.838 +/- 0.017)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10. s in the 10-1000 keV band
is 26.3 +/- 0.3 ph/s/cm^2.


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

C. K. Li, S. L. Xiong, X. B. Li, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang,
J. L. Zhao, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP),
Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),F. J. Lu, L. M. Song,
H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

At 2018-01-13T10:02:07.50 UT (T0), the Insight-HXMT/HE detected
GRB 180113C (trigger ID: HEB180113418) in a routine search of the data,
which was also triggered by Fermi/GBM (Veres et al. GCN 22334
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 ) and
INTEGRAL/SPI-ACS.

The Insight-HXMT light curve consists of multiple pulses
with a duration (T90) of 22.05 s measured from T0+4.17 s.
The 1-s peak rate, measured from T0+7.85 s, is 21741.2 cnts/sec.
The total counts from this burst is 235458.8 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB180113418_lc.jpg

All measurements above are made with the CsI detectors operating in the
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside
of the telescope.

The analysis results presented above are preliminary;
final results will be published elsewhere.

Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at:
http://www.hxmt.org/index.php/enhome .

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D.Svinkin,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 180113C (Fermi GBM detection: Veres et al.,
GCN 22334
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 ) was detected by Fermi(GBM), Konus-Wind, INTEGRAL(SPI-ACS),
Mars-Odyssey (HEND), and Swift(BAT) at about 36125 s UT (10:02:05).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   175.300 (11h 41m 12s) -63.261 (-63d 15' 40")
  Corners:
   173.892 (11h 35m 34s) -62.126 (-62d 07' 33")
   176.415 (11h 45m 40s) -64.502 (-64d 30' 07")
   176.856 (11h 47m 26s) -64.371 (-64d 22' 16")
   174.311 (11h 37m 15s) -62.002 (-62d 00' 07")
  ---------------------------------------------
The error box area is 2174 sq. arcmin, and its maximum
dimension is 2.67 deg (the minimum one is 13.8 arcmin).
The Sun distance was 82 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180113_T36129/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.

D. Frederiks, S. Golenetskii, R.Aptekar, 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 GRB 180113C (Fermi-GBM detection: Veres et al., GCN 22344
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 ;
Insight-HXMT/HE observation: Li et al., GCN 22343
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 ;
IPN Triangulation: Hurley et al., GCN 22349
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 )
triggered Konus-Wind at T0=36129.524 s UT (10:02:09.524)

The burst light curve shows a bright, multi-peaked pulse
with a total duration of ~80 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(2.9 �� 0.1)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+6.400, of (3.1 �� 0.3)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+37.888 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.78 (-0.05,+0.05),
the high energy photon index beta = -2.14 (-0.06,+0.05),
the peak energy Ep = 368 (-22,+24) keV,
chi2 = 108/96 dof.

The spectrum near the peak count rate (measured from T0+6.400 s
to T0+6.912 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.35 (-0.16,+0.20),
the high energy photon index beta = -2.09 (-0.18,+0.13),
the peak energy Ep = 429 (-76,+85) keV,
chi2 = 59/63 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB80113_T36129/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.