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GCN Circular 2604

Subject
Activivty of SGR 1806-20
Date
2004-05-28T13:46:43Z (21 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks
on behalf of Konus-Wind and Helicon/Coronas-F teams,

T. Cline on behalf of the Konus-Wind team, and

A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS
GRB team report:

Recently, Konus-Wind has detected seven SGR-like bursts
in the trigger mode:

  Date   Time,     Duration,   Fluence,       Peak Flux,           kT****
         s UT          s      (20-200 keV)   (20-200 keV)          keV
                              ergs/cm2       ergs/cm2 s
-----------------------------------------------------------------------
040427   47089.452  0.176  (3.43 +/- 0.07)E-6 (2.58 +/- 0.22)E-5 19+/-3

040519*  72250.485  1.376  (2.74 +/- 0.02)E-5 (3.19 +/- 0.09)E-5 21+/-2

040522** 31696.702  0.176  (2.16 +/- 0.06)E-6 (2.82 +/- 0.17)E-5 16+/-5

040522   45772.875  0.136  (1.33 +/- 0.04)E-6 (1.59 +/- 0.12)E-5 25+/-6

040523   50502.964  0.552  (4.32 +/- 0.09)E-6 (2.94 +/- 0.14)E-5 16+/-5

040525*** 12976.933 0.592  (8.74 +/- 0.12)E-6 (3.06 +/- 0.11)E-5 23+/-4

040526   29173.030  0.752  (5.88 +/- 0.11)E-6 (1.41 +/- 0.09)E-5 16+/-5
------------------------------------------------------------------------
*   - this burst was localized, the most like source
       of the burst is SGR 1806-20 (GCN 2603Loading...
 
 ).
**  - this burst was also detected by Helicon-Coronas-F in the
       background mode. Estimated time delay is consistent with
       SGR 1806-20 position.
*** - this burst was also detected by INTEGRAL SPI-ACS.
       We have triangulated it to an annulus centered at
       RA(2000) = 259.389 deg, Decl(2000) = -17.958 deg,
       whose radius is 12.616 +/- 1.770 deg (3 sigma).
       The center line of this annulus passes 0.4 degrees from
       the position of SGR 1806-20.
**** - the last column contains the values of spectral parameter kT
        for the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT)


Additionally, a number of SGR-like bursts (short and soft)
were detected by both Konus detectors S1 and S2
in the background mode:

  Date      Time,
         s UT  (hh:mm:ss)
---------------------------
040519  25976 (07:12:56)
040519  86378 (23:59:38)
040520  44823 (12:27:03)
040522   2693 (00:44:53)
040522  30582 (08:29:42)
040522  80762 (22:26:02)
040522  83738 (23:15:38)
040523  18673 (05:11:13)
040523  39091 (10:51:31)
040523  40937 (11:22:17)
040523  65789 (18:16:29)

The Konus ecliptic latitude response indicates
that the source of the bursts is near ecliptic plane.

All these data lead to the supposal
that the all these bursts originated from SGR 1806-20,
which, hereby, has entered a new phase of activity
in the hard X-ray.