GRB 190415A

Q. Luo, C. Cai, S. Xiao, 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 2019-04-15T04:09:49.900 (T0), the Insight-HXMT/HE detected
GRB 190415A(trigger ID: HEB190415173) in a routine search of the data,
which was also triggered by Fermi/GBM(F. Kunzweiler et al. ,GCN 24123)
and INTEGRAL.

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 24.74 s measured from T0+0.89 s.
The 1-ms peak rate, measured from T0+4.001 s, is 17011 cnts/sec.
The total counts from this burst is 100520 counts.
URL_LC: http://www.hxmt.org/images/GRB/HEB190415173_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.

Insight-HXMT is the first Chinese space X-ray telescope, which was
fundedjointly 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.

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

K. Hurley, on behalf of the IPN,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
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

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:

The long-duration GRB 190415A
(Insight-HXMT/HE detection: Luo et al., GCN Circ. 24125
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 )
was detected by Fermi (GBM trigger 576994194),
INTEGRAL (SPI-ACS), Konus-Wind, Swift (BAT), and Insight (HXMT/HE)
at about 14990 s UT (04:09:50).
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:
    28.053 (01h 52m 13s) +20.221 (+20d 13' 16")
  Corners:
    26.606 (01h 46m 25s) +21.774 (+21d 46' 27")
    27.221 (01h 48m 53s) +22.093 (+22d 05' 34")
    29.374 (01h 57m 30s) +18.606 (+18d 36' 22")
    28.770 (01h 55m 05s) +18.296 (+18d 17' 44")
  ---------------------------------------------
The error box area is about 2.6 sq. deg, and its maximum
dimension is 4.1 deg (the minimum one is 39 arcmin).
The Sun distance was about 10 deg.

This box may be improved.

The box lies outside the 1 sigma of the alternative
localization of the Fermi-GBM detection BALROG
(Kunzweiler et al., GCN Circ. 24123
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 ; ~0.6 deg stat. + 1 deg sys.),
while being consistent with 1 sigma contours of the Fermi-GBM final
position.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB190415_T14986/IPN

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

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

The long GRB 190415A (Insight-HXMT/HE detection: Luo et al.,
GCN 24125
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 ; IPN triangulation: Svinkin et al., GCN 24128
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 )
triggered Konus-Wind (KW) at T0=14986.024 s UT (04:09:46.024).

The light curve of the burst shows a bright, hard-spectrum,
multi-peaked pulse, which started at ~T0 s and had a duration of ~ 19s. 
This pulse was followed by a weaker and softer emission tail
of the emission detectable until ~T0+57 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190415_T14986/

As observed by Konus-Wind, the burst had
a fluence of (8.8 �� 0.8)x10^-5 erg/cm2 and
a 64-ms peak energy flux, measured from T0+5.824,
of (2.33 �� 0.14)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV
energy range).

The time-integrated spectrum (measured from T0 to T0+56.512 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.65(-0.10,+0.11),
and the peak energy Ep = 892(-99,+120) keV,
chi2 = 94/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta (-3.1).

The spectrum near the peak count rate (measured from T0 to T0+7.360)
is best fit in the 20 keV - 15 MeV range by
the CPL function with the following model parameters:
the photon index alpha = -0.17(-0.09,+0.10),
and the peak energy Ep = 994(-62,+67) keV,
chi2 = 89/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta (-3.8).

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