EUropean REtrievable CArrier
(EURECA) Archive System
NASA Langley Research Center
Hampton, Virginia
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Responsible Parties:
Page Content: William H. Kinard Page Construction: Thomas H. See |
Overview
August 1992 - July 1993
The European Retrievable Carrier (EURECA) was launched on July 31, 1992 by the Space Shuttle Atlantis, and placed into an orbit at an altitude of 508 km. It began its scientific mission on August 7, 1992. Nearly one year later, EURECA was retrieved on July1, 1993 by the Space Shuttle Endeavor and returned to Earth. The satellite carried a number of experiments for microgravity studies, solar observations, and material technology investigations. Also on board was the WATCH or the Wide Angle Telescope for Cosmic Hard X-rays (WATCH) instrument.
Instrumentation
The WATCH instrument was sensitive to 6-150 keV photons. The total field of view covered 1/4 of the celestial sphere. During its 11 month lifetime, EURECA tracked the Sun and WATCH gradually scanned across the entire sky. The WATCH instrument was developed at the Danish Space Research Institute and also flown on the Russian Granat mission. WATCH is a wide-field monitor based on the Rotation Modulation Collimator principle. It has a circular field of view with a radius of about 65 degrees. There are two interleaved detectors which create a phoswich of alternating strips of NaI(Tl) and CsI(Na). Each strip is 5 mm wide by 2 mm thick The diameter of the phoswich is 110 mm and it is viewed across a 10 mm air gap by a single 125 mm photomultiplier. The effective area of the NaI and CsI scintillators if about 45 cm2. The sensitivity is about 100 mCrab in one day. The effective observation time for the 318 day mission was 120 days. The minimum time resolution was 64 microseconds.
Science
Some two dozen known X-ray sources were monitored - some for more than 100 days. In addition, a number of new X-ray transients were discovered and nineteen cosmic gamma-ray bursts were detected by the WATCH instrument, with 12 of these being localized to within ~ 1 degree.
References
Brandt and Lund 1995, Adv Sp Res, 16, pp. 837-842.
Brandt, Lund, and Castro-Tirado 1995, Adv Sp Res, 16, pp. 843-846.
Lund 1985, X-Ray Instrumentation in Astronomy, SPIE 597, pp. 95-100.
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