The Konus/WIND Experiment

Launched in November 1994, the WIND spacecraft is mainly devoted to the study of the solar wind, and for this reason has been inserted into a special "halo" orbit in the solar wind upstream from the Earth, about the sunward Sun-Earth equilibrium point (L1). It has a spin period of $\sim$ 20 s, with the spin axis normal to the ecliptic. The Konus experiment, which is the first Russian scientific instrument to fly on an American satellite since space cooperation between the U.S. and Russia was resumed in 1987, provides omnidirectional and continuous coverage of the sky in the hard X- and gamma-ray domain. In addition to GRBs, it also monitors soft gamma repeaters (SGRs), solar flares, and other transients with the moderate energy resolution available from scintillation spectrometers. It provides event light curves in three energy bands within the 10-770 keV range, with 64 ms time resolution. In addition, 2 ms resolution is available for at least some parts of triggered bursts. Finally, the gamma-ray and particle backgrounds are continuously monitored as well, except for interruptions to readout burst profiles.

It consists of two detectors and an electronics package from Russia, and an interface unit from Goddard. The two identical detectors are mounted on the top and bottom of the spacecraft aligned with the spin axis; the other two assemblies are in the spacecraft body. The sensors, copies of ones successfully flown on earlier Soviet COSMOS, VENERA and MIR missions, and similar to the spectroscopy modifications of the BATSE/CGRO, are scintillation crystal detectors of 200 cm$^2$ area, shielded by Pb/Sn. Quasi-isotropic sensitivity is a result of the design and location of the two sensors. In interplanetary space far outside the Earth's magnetosphere, Like Ulysses and all the over Earth- orbiting spacecrafts, Konus has the advantages of continuous coverage, without Earth occultations, and, above all, a steady background, undistorted by passages through the South Atlantic Geomagnetic Anomaly (SAGA).

Finally, the comparisons of the event count rates from the two Konus detectors can provide a spacecraft spin elevation measurement that translates to an ecliptic latitude source locus. This feature often contributed to determining the GRB position, through its intersection with other error boxes, like IPN annuli, thus solving the usual IPN redundancy, like the GRBM did in some cases (see, for instance, the IPN triangulation in the case of GRB010923, fig ). This broad feature, when other source determinations, such as from BeppoSAX or Rossi-XTE, are absent, enables the resolution of the IPN source ring intersection redundancy.