E.P.Mazets, R.L.Aptekar, D.D.Frederiks, S.V.Golenetskii, V.N.Il’inskii, V.D.Pal’shin, M.V.Ulanov

1. 10 years of GRBs observations from the joint Russian-American KONUS-WIND experiment: results and perspectives E.P.Mazets, R.L.Aptekar, D.D.Frederiks, S.V.Golenetskii, V.N.Il’inskii, V.D.Pal’shin, M.V.Ulanov A.F.Ioffe Physico-Technical Institute, St.Petersburg, Russia T.L.Cline, P.S.Butterworth NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

2. Main results of the KONUS experiments on the “Venera 11-14” missions (1979-83) • A number of types of GRBs with different time history and duration distribution were studied. • Short GRBs were indicated as a separate class. • Sources of soft repeating bursts were discovered. • The energy spectra of GRBs were investigated. A rapid spectral variability was found. • Localization of 160 sources of GRBs revealed their isotropic distribution on the celestial sphere.

3. GRBs duration distribution. Data of Konus experiments on Venera 11-14 (1979 – 1983) GRBs bimodal distribution

4. Konus GRBs distribution BATSE GRBs distribution GRBs celestial distribution

5. Wind Instruments

6. Wind trajectory during extended mission phase 10: Low-inclination phasing orbit July 2002 to November 2002 XY (ecliptic plane) projection Wind trajectory during extended mission phase 11-13: L1 excursion  L2 excursion  L1 Lissajous orbit (2002-2008+) XY (ecliptic plane) projection Wind trajectory

7. Scientific objectives of Konus-Wind experiment • study of GRBs including a determination of their occurence rate above a sensitivity threshold of ~ 10-7 erg cm-2, detailed measuring of the time histories of bursts with high time resolution of 2 – 64 milliseconds, detailed spectral measurements in the broad energy range of 10 keV – 10 MeV, investigations of a fast spectral variability on a time bin scale of a few milliseconds; • precise localization of GRBs by means of an arrival time triangulation method together with other Interplanetary Network (IPN) spacecraft using the Wind s/c as a constant and effective vertex of the IPN; • comprehensive study of the Soft Gamma Repeater (SGR) – very rare astrophysical objects in our Galaxy thought to be neutron stars with a huge magnetic field of 1014 - 1015 G – including a monitoring of a long-term variations of their activity and waiting for exceptional rare giant flares in SGR’s with energy release up to 1044 erg; • detection and study much more slower gamma-ray transients especially those which are coming from objects believed to contain a black hole.

8. Konus-Wind Gamma-Ray Burst Experiment on US GGS-Wind spacecraft • Two detectors S1 and S2: NaI(Tl) 13 cm diameter, 7.5 cm height, 12.5 cm Be window. Located on opposite faces of spacecraft, observing correspondingly the southern and northern celestial hemispheres • Burst mode: Time history analyzer: resolution 2ms – 256 ms, total duration 230s 12 – 50 keV 4096 ch 50 – 200 keV 4096 ch 200 – 770 keV 4096 ch

9. Instrument description (continue) • Pulse Height analyzer: accumulation time 64ms – 8.192 s, duration 79 – 492 s PHA1 12 – 770 keV 63 ch quasilog scale PHA2 0.2 – 10 MeV 63 ch quasilog scale • Background mode: accumulation time 1.47 – 2.94 s Count rate: 12 – 50 keV 50 – 200 keV 200 – 770 keV > 10 MeV

10. Joint Russian-American experiment on US GGS-WIND spacecraft Launch: November 1, 1994 Konus-Wind instrument switched on: November 11, 1994 Orbit: beyond the magnetosphere of the Earth Observations: November 11, 1994 –December 18, 2004 ( 3689 days) Gamma ray bursts total 2524 Burst mode 1419 Background mode 1105 Solar flares 729 Konus-Wind Summary

11. GRB 980706a – an example of short hard GRB. Ep = 1.6 MeV. Konus-Wind GRBs

12. Konus-Wind GRBs • GRB 041211 – a recent example of long multipeak hard GRB.

13. Duration distribution of Konus-Wind trigger GRBs

14. KONUS-WIND GRB 991208 T0= 16613.263s UT Two pulses with clear spectral evolution Fast spectral variability of GRB 991208

15. Pulse 1 Pulse 2 Fast spectral evolution of GRB 991208

16. Fast spectral variability of GRB 970828

17. GRB 970228 was localized by BeppoSAX WFC (IAUC 6572) Independent IPN Ulysses/Wind triangulation (IAUC 6593) X-ray and optical transient was found z = 0.695 ± 0.002 Konus-Wind-Ulysses-Konus-A localization for GRB 970228

18. Localization of GRB 010109

19. Konus-Wind observations of Soft Gamma Repeaters • Konus-Wind detected more than 150 trigger SGR bursts from 4 SGRs: 1900+14, 1806-20, 1627-41, 1801-23. • Numerous SGR bursts were detected in the background mode • Giant outbursts were detected from SGR 1900+14 and SGR 1627-41 • Series of bursts were detected from SGR 1900+14 and recently from SGR 1806-20 (GCN 2769) • Now Konus-Wind continue to register bursts from SGR 1806-20, which stay in active state

20. SGR 0526-66 • Burst 790306 detected from SGR 0526-66 by Konus on Venera 11

21. Burst 790324 - the first burst detected from SGR 1900+14 by Konus on Venera-11 Burst 980902b – a typical burst from SGR 1900+14 detected by Konus-Wind Konus-Wind observations of SGR 1900+14

22. Burst 040828 – the most intense burst (both in peak flux and fluence) detected by Konus-Wind from this SGR. SGR 1806-20

23. An intense burst 980625 from SGR 1627-41 which demonstrates strong spectral evolution typical for this SGR. SGR 1627-41

24. Time and energy characteristics of the August 27 event. Top: Background subtracted light curve of the outburst. Horizontal sections with triangles specify count rates averaged over the period. The sloped dashed line is a plot of exp(-t/t) for t = 91.5 s. Bottom: Horizontal sections with squares specify kT averaged over the period. Giant outburst on 1998 August 27 (SGR 1900+14)

25. Time and energy characteristics of the March 5 event. Top: Background subtracted light curve of the outburst. Horizontal sections with triangles specify count rates averaged over the period. The sloped dashed line is a plot of exp(-t/) relation for t=100 s. Bottom: Horizontal sections with squares specify kT averaged over the period. Giant outburst on 1979 March 5 (SGR 0526-66)

26. Time and energy characteristics of the June 18 event. Top: Background subtracted light curve of the outburst. period. The rise time os about 100 ms. Bottom: Spectral evolution during the burst. Giant outburst on 1998 June 18 (SGR 1627-41)

27. New SGR 1801-23 • New SGR was discovered by Wind, Kosmos2326, CGRO, and Ulysses • Only 2 short bursts from this source were detected up to date Burst 970629b T0=23493.221 s UT

28. the Cyg X-1 outburst on 950325 as observed by Konus-Wind The narrow spike at 25,841 s in the beginning of interval B is the GRB that triggered a series of multichannel spectral measurements, covering the entire interval B. The gap after B was caused by the transmission of high-resolution data to the onboard tape recorder. Background levels are indicated by the dashed lines. Giant outbursts from Gygnus X-1

29. Konus F spectrum of the outburst on 950325. The spectrum was accumulated during the decay stage of the flare over 360 s of interval B with moderate statistics. The solid curve is the result of the spectral fit. The spectral shape is consistent with that of the hard state of Cyg X-1. Giant outbursts from Gygnus X-1 (continue)

30. Konus 15–300 keV photon fluxes (background subtracted) and hardness ratios for the outburst on 020224. The time resolution is 23.552 s. Giant outbursts from Gygnus X-1 (continue)

31. Konus-Wind observations of GRBs with known redshifts • Konus-Wind has been successfully operating since November 1994. Of more than 30 GRBs with known redshifts, Konus-Wind has detected 23 GRBs in the trigger mode and 7 in the background mode. It is the largest subset of GRBs with known redshifts collected by one instrument.

32. Konus-Wind light curve of the famous GRB 030329. Fluence: (1.74±0.01)×10-4erg cm-2. Peak Flux: (2.62±0.04)×10-5 erg cm-2 s-1 26 high resolution spectra were obtained with Ep varies from 30 to 180 keV. Konus-Wind observations of GRBs with known redshifts: GRB 030329 (z=0.1685)

33. Correlation of isotropic equivalent maximal Luminosity with Ep (in the source rest frame) for Konus-Wind GRBs with known redshifts. Konus-Wind observations of GRBs with known redshifts

34. Main scientific results of the Konus-Wind experiment • in the course of Konus-Wind experiment more than 1400 GRBs were detected in a triggered mode with high time and spectral resolution; • Time histories, energy spectra, a fast spectral variability, and inherent correlations in the bursts have been studied; • the IPN with Konus-Wind as a basic vertex has precisely localized a large number of GRB sources by triangulation method, producing crucial data for the multiwavelength study of the GRB afterglows with many telescopes, both ground-based and in orbit;

35. Main scientific results of the Konus-Wind experiment (continue) • A comprehensive study of SGRs was carried out. Two new sources, SGR1627-41 and SGR1801-23 were discovered in addition to three known SGRs. The Konus-Wind experiment was succeeded in detailed studying of the huge outburst in SGR1900+14 on August 27, 1998. It was the second observed giant flare in SGRs after the famous March 5, 1979 event in SGR0526-66. Third giant flare was observed from the new SGR1627-41. • About more than 300 more common repeating bursts were observed in SGRs at revealed phases of their burst activity; • Rare strong and long outbursts from Cygnus X-1 were discovered. Such type of its behavior represents a new feature of gamma-ray emission of binary system contained a black hole.

36. The Konus-Wind experiment data collection, archiving and dissemination. • Obtained information are stored on CD ROM’s at GSFC and at Ioffe Institute. To make it available for scientific community several websites were opened. • Time histories of GRB’s given with the time resolution of 64 ms are available though GCN website at GSFC (http://gcn.gsfc.nasa.gov ) immediately after receiving telemetry data on the ground. • Two complete sets of an accumulated information, “Konus Catalog of Soft Gamma Repeater Activity: 1978 to 2000” and “Konus Catalog of Short GRBs” are presented on the Ioffe Institute websites at http://www.ioffe.rssi.ru/LEA/SGR/Catalog/ ,and http://www.ioffe.rssi.ru/LEA/shortGRBs/Catalog/ , respectively. • The complete catalog of all observed GRBs is now in preparation

37. Perspectives of the Konus-Wind experiment • The Konus-Wind experiment remains an important source of time resolved GRB’s spectral data in the wide energy range from 15 keV up to 12 MeV. This information is a real contribution in the GRB’s multiwavelength study as a whole and especially for GRBs detected by SWIFT, since the spectral coverage of the SWIFT BAT instrument is extremely limited (about 20 – 150 keV). Recent developments in our understanding of GRBs suggest that broad-band spectral information about prompt GRB emission can provide important constrains on models.