GRB 190515A

S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin(AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN),  Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC),  M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The short hard GRB 190515A (Fermi-LAT detection: Kocevski et al.,
GCN Circ. 24560
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 ; Fermi GBM detection: Roberts, GCN Circ. 24562
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 )
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 04:33:03.330 UTC
on 15 May 2019. The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse which starts at T+0 sec,
peaks at T+0.19 sec and ends at T+0.45 sec. The T90 and T50 durations
measured by the SGM data are 0.38 +- 0.14 sec and
0.19 +- 0.06 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1241929925/

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

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

At 2019-05-15T04:33:03.000 (T0), Insight-HXMT/HE detected 
GRB 190515A(trigger ID: HEB190515189) in a routine search of the data, 
which was also triggered by Fermi/GBM (GCN#24550
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 ), Fermi/LAT (D. Kocevski 
et al., GCN#24560
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 ) and Swift/XRT (M. J. Moss et al., GCN#24553
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 ). 

The Insight-HXMT/HE light curve mainly consists of single  
pulse with a duration (T90) of 0.44 s measured from T0+0.02 s. 
The 1-ms peak rate, measured from T0+0.20 s, is 5641 cnts/sec. 
The total counts from this burst is 1906 counts. 
URL_LC: http://www.hxmt.org/images/GRB/HEB190515189_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 (deposited 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. 

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.

O.J. Roberts (USRA/NASA-MSFC) reports on behalf of the Fermi GBM Team:

"At 04:33:03.14 UT on the 15th May 2019, the Fermi Gamma-ray Burst Monitor
(GBM)
triggered and located GRB 190515A (trigger 579587588 / 190515190), which was
also detected by the LAT (Kocevski et al. 2019, GCN 24560
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 )
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight is 44 degrees.

The GBM light curve shows a bright short spike with a duration (T90)
of about 0.5 s (10-1000 keV). The time-averaged spectrum from
T0-0.26 s to T0+0.38 s is best fit by a power law function with
an exponential high-energy cutoff.  The power law index is
-0.4 +/- 0.2 and the cutoff energy, parameterized as Epeak,
is 960 +/- 251 keV.

The event fluence (10-1000 keV) in this time interval is
(1.233 +/- 0.070)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.2 s in the 10-1000 keV band
is 8.2 +/- 0.9 ph/s/cm^2."

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"

D. Kocevski (NASA/MSFC), M. Axelsson (KTH and Stockholm Univ.), L. Scotton (INFN Torino), E. Burns (NASA/GSFC), and M. Arimoto (Kanazawa Univ.) report on behalf of the Fermi-LAT team: 

At 04:33:03 on 2019-05-15, Fermi-LAT triggered on high-energy emission from short GRB 190515A, which was also detected by Fermi-GBM  (trigger 579587588/190515190).

The best LAT on-ground location is found to be

RA, Dec = 137.687 , 29.276 (J2000) 

with an error radius of 0.907 deg (90% containment, statistical error only). This was 44 deg from the LAT boresight at the time of the trigger and 10 deg from the center of the GBM localization (GCN 24550
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 ).

The data from the Fermi-LAT show a significant increase in the event rate that is temporally correlated with the GBM emission with high significance. The highest-energy photon is a 874 MeV event which is observed 3 seconds after the GBM trigger.

The photon flux above 100 MeV in the time interval 0-300s after the GBM trigger is 6.5e-06 ph/cm2/s +/- 2.4e-06. The estimated photon index above 100 MeV is -2.6 +/- 0.5.

The Fermi-LAT point of contact for this burst is Magnus Axelsson (magnusa@fysik.su.se). 

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

The Fermi GBM team reports the detection of a likely SHORT GRB

At 04:33:03 UT on 15 May 2019, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 190515A (trigger 579587588.135176 / 190515190).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 137.2, Dec = 39.3 (J2000 degrees, equivalent to J2000 09h 08m, 39d 17'), with a statistical uncertainty of 5.0 degrees.

The angle from the Fermi LAT boresight is 35.0 degrees.

The skymap can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190515190/quicklook/glg_skymap_all_bn190515190.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190515190/quicklook/glg_healpix_all_bn190515190.fit

The GBM light curve can be found here:
http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2019/bn190515190/quicklook/glg_lc_medres34_bn190515190.gif