GRB 180112A

C. Z. Liu, X. F. Li, S. L. Xiong, X. B. Li, C. K. 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 16:30:38.00 UT on January 12 2018, the Insight-HXMT/HE detected 
GRB 180112A(Insight-HXMT internal trigger ID: HEB180112687 and HEB180112689, 
corresponding to two main pulses) in a routine search of the data, 
which was also triggered by Swift/BAT and Integral/SPI-ACS and CALET/CGBM.

It's a pulsating GRB event. The Insight-HXMT light curve consists of 
two bursts triggered respectively at 16:30:38.00 UT and 16:32:56.00 UT, 
each of the two bursts consists of multiple pulses. The GRB event totally has a 
duration (T90) of 151.788 s measured from T0-5.2385 s. The 1s peak rate, 
measured from T0+139.541 s, is 1383.0 cnts/sec. The total counts from 
this GRB event is 4935.2 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB180112687_lc.jpg

All measurements above are made with the CsI detectors operating in the
GRB mode with the energy range of about 200-3000 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 .

S. Ozawa (Waseda U), A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo,
M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 180112A (INTEGRAL SPI-ACS trigger #7990;
Konus-Wind trigger time on 16:29:11.736) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 16:29:08.39 on 12 January 2018.  The burst signal
was seen by the all CGBM instruments.

The light curve of the SGM shows three isolated episodes.  The first weak
episode peaks around T+2 sec with the duration of 4 sec.  The second
episode has two overlapping pulses, and its emission starts at T+80 sec,
peaks at T+100 sec and ends at T+110 sec.  The third brightest episode
has a single pulse, and its emission starts at T+200 sec, peaks at T+230 sec
and ends at T+250 sec.  The T90 and the T50 durations measured by the
SGM data are 155 +- 80 sec and 134.5 +- 1.2 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1199809543

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

Y. Sharma (IITB), V. Sharma (IUCAA), Arvind B. (IISER Pune), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat CZTI data showed the detection of long duration GRB 180112A, which was also detected by Insight-HXMT (C. Z. Liu et al., GCN 22353
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 ), CALET (S. Ozawa et al., GCN 22358
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 ), Konus Wind (Trigger time: 16:29:11.736) and INTEGRAL SPI-ACS (Trigger time : 16:30:38).

The source was clearly detected in the 40-200 keV energy range. The light curve shows three distinc peaks, starting with a weak peak at 16:29:09 (UT) followed by two strong peaks at 16:30:45 (UT) and 16:32:54 (UT) respectively. The measured peak count rate is 96 cts/s above the background in combined data of four quadrants, with a total of 37730 cts. The local mean background count rate was 479 cts/s. Using cumulative rates, we measure a T90 of 209 s.

All three peaks of GRB were also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.