Abstract
THE Imperial College scintillation detector on Ariel V made measurements of the X-ray spectrum of the Crab Nebula in 1975 April and September. The detector consists of an 8cm2×4 cm CsI(Na) crystal actively collimated to 8° FWHM, and measures X rays in 15 logarithmically spaced energy channels in the range 26 keV–1.2 MeV. The detector axis is inclined 3° to the spacecraft spin axis, which in turn is normally offset by ∼ 3° from the source being viewed. Source counts are thus spin modulated, allowing the background to be subtracted. A residual modulation is further removed by changing the direction of the offset to the source and observing the resulting phase change in the modulation. This observational technique ensures all sources of background are eliminated, the modulation characteristics having been previously determined by laboratory calibration.
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References
Toor, A., and Seward, F. D., Astr. J., 79, 995 (1974).
Baker, R. E., Lovett, R. R., Orford, K. J., and Ramsden, D., Nature phys. Sci., 245, 18 (1973).
Schonfelder, V., Lichti, G., and Moyano, C., Nature, 257, 375 (1975).
Kniffen, D. A., et al., Nature, 251, 397 (1974).
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CARPENTER, G., COE, M. & ENGEL, A. New X-ray measurements of the Crab spectrum in the range 26 keV–1.2 MeV. Nature 259, 99 (1976). https://doi.org/10.1038/259099a0
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DOI: https://doi.org/10.1038/259099a0
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