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GRB 170827B

GCN Circular 21735

Subject

IPN Triangulation of GRB 170827B (short)

Date

2017-08-28T19:07:06Z (8 years ago)

From

Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

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,

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

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 short GRB 170827B was detected by Fermi (GBM trigger 525555489),
Konus-Wind, INTEGRAL (SPI-ACS), and Swift (BAT)
at about 70684 s UT (19:38:04).
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
  ---------------------------------------------
  Corners:
    55.251 (03h 41m 00s) -21.923 (-21d 55' 22")
    53.829 (03h 35m 19s) -23.046 (-23d 02' 44")
     5.177 (00h 20m 42s) -74.042 (-74d 02' 32")
     7.290 (00h 29m 10s) -72.425 (-72d 25' 28")
  ---------------------------------------------
The error box area is 74 sq. deg, and its maximum
dimension is 99.7 deg (the minimum one is 77.2 arcmin).
The Sun distance was 104 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170827_T70686/IPN

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

GCN Circular 21775

Subject

Konus-Wind observation of GRB 170827B

Date

2017-08-31T14:13:20Z (8 years ago)

From

Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

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

The short-duration GRB 170827B
(IPN Triangulation: Svinkin et al., GCN Circ. 21735Loading...
 
 )
triggered Konus-Wind at T0=70686.844 s UT (19:38:06.844).

The burst light curve shows a single pulse which starts
at ~T0-0.150 s and has a total duration of ~0.180 s.

As observed by Konus-Wind, the burst
had a fluence of 4.2(-0.8,+1.1)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0+0.018 s,
of 3.8(-1.3,+1.5)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from T0-0.148 s to T0+0.032 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -0.21(-0.34,+0.56) and Ep = 345(-79,+121) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170827_T70686/

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.