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Physical Sciences: New X-ray Pulsar near the Crab Nebula


ON October 17, 1970, a new X-ray pulsar was observed with a balloon-borne X-ray telescope launched from Palestine, Texas. The detector consisted of three proportional counters filled with xenon at 2.5 atm. The total effective area was 480 cm2, and the sensitivity extended from 30–100 keV with an average efficiency of 80%. A multigrid collimator provided a field of view of 3° FWHM in elevation and 12° FWHM in azimuth. Data were recorded from the Crab Nebula between 4.00 and 8.00 CST. Each count was telemetered to the balloon base and recorded on analogue magnetic tape with a resolution in pulse arrival time of 0.1 ms. The magnetic tape also contained reference timing signals, stable to better than 5 parts in 109. The Crab pulsar NP 0532 was clearly detected1.

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    Smathers, H. W., Chubb, T. A., and Sadeh, D. S., Nature, 232, 120 (1971).

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    Zeissig, G. A., and Richards, D. W., Nature, 222, 150 (1969).

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    Manchester, R. N., Astrophys. J. Lett., 167, L101 (1971).

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    Blackman, R. B., and Tukey, J. W., The Measurement of Power Spectra (Dover, New York, 1958).

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    Giacconi, R., Gursky, H., Kellogg, E., Schreier, E., and Tananbaum, H., Astrophys. J., 167, L67 (1971).

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