[vsnet-grb-info 7288] Konus-Wind observation of AXP/SGR 1E1547.0-5408 bursting activity

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8858
SUBJECT: Konus-Wind observation of AXP/SGR 1E1547.0-5408 bursting activity
DATE:    09/01/28 13:50:34 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val at mail.ioffe.ru>

S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P.
Oleynik, M. Ulanov and T. Cline, on behalf of the Konus-Wind team,
report:

Since the renewal of bursting activity of the AXP/SGR 1E1547.0-5408
on January 22 (Gronwall et al., GCN 8833; Connaughton & Briggs, GCN 
8835; von Kienlin & V. Connaughton, GCN 8838; Savchenko et al. GCN 8837;
Terada et al., GCN 8845; Bellm et al., GCN 8857) Konus-Wind have seen 11 
triggers from this source.

The first trigger at 2009-01-22 T0=3554.882 s UT (00:59:14.882) contains 
many bursts and represent the cluster of bursts which started at 
~T0-210s. The second trigger also contains several bursts. Remaining 
triggers contain single bright bursts.

There is a data gap from 02:13 to 15:43 UT on Jan 22, 2009 which cannot 
be recovered.

The following is a list of the Konus-Wind triggers with preliminary 
estimations of the bursts fluences and peak fluxes. The KW trigger times 
and corresponding Earth-crossing times are given.
-------------------------------------------------------------------

#   Date     T0(KW)       T0Earth   Localized   Fl**  PF**
               UT           UT          by
-------------------------------------------------------------------
1* 20090122 00:59:14.882 00:59:18.550 GBM      8.0 8.0
2* 20090122 02:09:22.183 02:09:25.849 BAT      5.7 1.3
3  20090122 17:02:52.833 17:02:56.474 BAT      2.7 2.5
4  20090122 21:07:56.190 21:07:59.824  -       1.0 3.4
5  20090122 23:14:50.460 23:14:54.090 GBM      4.7 7.8
6  20090123 01:19:37.838 01:19:41.465 BAT,GBM  2.7 7.5
7  20090123 02:42:05.150 02:42:08.774 GBM      3.2 9.7
8  20090123 16:54:33.488 16:54:37.087 GBM      1.3 5.6
9  20090125 08:43:37.781 08:43:41.303 IBIS    250  300
10 20090125 23:00:32.802 23:00:36.294 IPN,GBM  7.6 19
11 20090126 04:48:01.917 04:48:05.397 GBM      1.6 5.7
------------------------------------------------------------------
* - these triggers contain several bursts, in Table we give total
     fluence of all bursts and peak flux of the brightest burst

** - Fluence (20-200 keV) in units of 1e-6 erg/cm2

*** - Peak Flux (20-200 keV) on 4ms time scale
       in units of 1e-5 erg/cm2/s

Some Abbreviations:
BAT: Swift BAT
GBM: Fermi GBM
IBIS: Imager on Board the INTEGRAL Satellite
IPN: Interplanetary Network


The spectra of the most bursts are well fitted (in the 20-500 keV energy 
range) by power low with exponential cutoff model with Epeak values in 
the 25-35 keV range. Some bursts demonstrate strong spectral evolution.
Some spectra can be well fitted by simple power law model.

The burst #3 while having moderate fluence has a peculiar spectrum. It 
is well fitted by grbm model with alpha ~-1, Ep ~40, and beta ~-3.2 
(cutoffpl model provides much worse chi2), the emission is seen up to 
500 keV.

The burst #9 (Golenetskii et al., GCN 8851) is the brightest burst 
detected by Konus-Wind from this AXP/SGR. It has the hardest spectrum 
with Epeak ~70 keV. Its duration (~400ms), energy output ~2.4x10^42 erg 
(for d=9 kpc), and peak luminosity ~2.9x10^43 erg/s are close to the 
characteristics of the famous event 980618a from SGR 1627-41 (dT~0.5 s, 
Q = 3x10^42 erg, L = 8x10^43 erg/s for d=5.8 kpc: see Mazets et al., 
ApJ, 519, L152 (1999)). There is no any sign of pulsating tail in both 
cases.

The second burst in brightness (#10) has the second in hardness spectrum 
with Ep ~45 keV.

Numerous short soft bursts most likely originated from this source were 
detected by Konus-Wind in the waiting mode.

We thank Sandro Mereghetti for poiting our attention to the IBIS/ISGRI 
localization of the very bright SGR burst 090125 (T0=31417.781 s UT 
08:43:37.781).

We thank David Palmer for providing us with the information about BAT 
observations of the KW bursts.

We also thank all IPN teams which provided us with the information about 
observations of the KW bursts by their instruments.