New Solar Broad-Band Hard X-Ray Spectrometer: First Results

The scientific and operational aims of the Czech-made Hard X-Ray Spectrometer (HXRS) launched onboard the U.S. Department of Energy Multispectral Thermal Imager satellite (MTI), on 12 March 2000 are discussed. The principal operating characteristics of the instrument such as the temporal resolution, energy band selection, spectral sensitivity, and the in-flight calibration procedure are described as well as the technical details of the spectrometer including detectors, shielding (against charged particles) and electronic design. The MTI host satellite and its orbit are briefly described. Recent observations by the 3 GHz Ondřejov radiometer are compared with HXRS data to demonstrate one example of the HXRS data utilization: the temporal relation between hard X-rays and radio emission. These results show relatively long time delays (2–14 s) of the GHz broadband radio pulses relative to the hard X-ray emission peaks. Access to the HXRS data base via the Internet is provided.