[vsnet-grb-info 8216] IPN Triangulation and Konus-Wind observaions of GRB090727B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9743
SUBJECT: IPN Triangulation and Konus-Wind observaions of GRB090727B
DATE:    09/08/03 11:35:38 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

S. Golenetskii, R. Aptekar, D. Frederiks, E. Mazets, and V. Pal'shin,
on behalf of the Konus-Wind team,

K. Hurley and T. Cline, on behalf of the Mars Odyssey
and Konus GRB teams,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team, and

J. Goldsten, on behalf of the MESSENGER NS GRB team,
report:


The long GRB 090727B triggered Konus-Wind at T0=84749.412 s UT
(23:32:29.412). The burst had a smooth temporal structure with
a duration of ~25 s. The Konus-Wind light curves are available at
http://www.ioffe.ru/LEA/GRBs/GRB090727_T84749/

This GRB was observed by Odyssey (HEND and GRS) and MESSENGER (GRNS).
Wind-Odyssey-MESSENGER triangulation, together with Konus-Wind
ecliptic latitude constrains, lead to the following preliminary,
3 sigma error box, which area is 1.00 sq. deg.

-----------------------------------------------
        RA(2000), deg            Dec(2000), deg
-----------------------------------------------
Center:
   343.358 (22h 53m 26s)   -46.700 (-46d 42' 00")
Corners:
   343.427 (22h 53m 42s)   -45.867 (-45d 52' 01")
   342.516 (22h 50m 03s)   -45.873 (-45d 52' 22")
   343.285 (22h 53m 08s)   -47.527 (-47d 31' 37")
   344.214 (22h 56m 51s)   -47.507 (-47d 30' 25")
-----------------------------------------------
IPN triangulation map can be found at
http://www.ioffe.ru/LEA/GRBs/GRB090727_T84749/GRB20090727_84749_IPN.png

As observed by Konus-Wind, the burst had a fluence
of (1.15 ± 0.15)x10-5 erg/cm2,
and a 256-ms peak flux, measured from T0+14.336 s,
of (8.5 ± 3.2)x10-7 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+24.832 s) is well fit, in the 20 keV - 2 MeV range,
by GRB (Band) model, for which:
the low-energy photon index alpha = -0.18(-0.27,+0.34),
the high energy photon index beta = -2.97( < -2.50),
the peak energy Ep = 152(-16, +17) keV (chi2 = 54/57 dof).

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

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