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TITLE:   GCN CIRCULAR
NUMBER:  22550
SUBJECT: IPN Triangulation of GRB 180326A (long)
DATE:    18/03/26 18:13:59 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind 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 180326A has been detected by Konus-Wind,
INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND), so far, at about 12367 s UT 
(03:26:07).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   291.728 (19h 26m 55s) -13.553 (-13d 33' 10")
  Corners:
   291.335 (19h 25m 20s) -13.809 (-13d 48' 34")
   291.286 (19h 25m 09s) -12.172 (-12d 10' 20")
   292.121 (19h 28m 29s) -13.297 (-13d 17' 48")
   292.210 (19h 28m 50s) -15.184 (-15d 11' 04")
  ---------------------------------------------
The error box area is 1.37 sq. deg, and its maximum
dimension is 3.14 deg (the minimum one is 46.9 arcmin).
The Sun distance was 74 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180326_T12367/IPN

The time history and spectrum will be given in forthcoming
GCN Circulars.

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TITLE:   GCN CIRCULAR
NUMBER:  22553
SUBJECT: Konus-Wind observation of GRB 180326A
DATE:    18/03/27 14:23:52 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 180326A
(IPN Triangulation: Hurley et al., GCN 22550)
triggered Konus-Wind at T0=12367.064 s UT (03:26:07.064).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~20.6 s.
The emission is seen up to ~6 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.19(-0.30,+0.36)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.336 s,
of 9.16(-2.36,+2.52)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.55(-0.20,+0.24)
and Ep = 767(-142,+200) keV (chi2 = 80/80 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 80/79 dof)

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model
with alpha = -0.61(-0.20,+0.23)
and Ep = 806(-151,+208) keV (chi2 = 85/80 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 85/79 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180326_T12367/
We note the MAXI J1820+070 activity seen in the waiting mode data.

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