Abstract
ARYABHATA, India's first artificial satellite, which was launched into a near circular orbit of 600 km altitude at an inclination of 51° on April 19, 1975, carried instruments to investigate celestial X rays in the energy range 2.5–155 keV. We report here observations of Cyg X-1 made in the range 2.5–18.75 keV, during the second orbit of the satellite, centred around 108 d 9 h 17 min 40 s UT, just before the source made a major increase in its intensity. We found a hardening in the spectrum.
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References
Heise, J., et al., Nature, 256, 107 (1975).
Holt, S. S., et al., Nature, 256, 108 (1975).
Sanford, P. W., et al., Nature, 256, 109 (1975).
Tananbaum, H., et al., Astrophys. J. Lett., 177, L5 (1972).
Rothschild, R. E., et al., Astrophys. J. Lett., 189, L13 (1974).
Mason, K. O., et al., Astrophys. J. Lett., 192, L65 (1974).
Rao, U. R., et al., Proc. Symp. on Fast Transient in X and gamma rays COSPAR/IAU, Varna, Bulgaria, May 30 (1975).
Thorne, K. S., and Price, R. H., Astrophys. J. Lett., 195, L101 (1975).
Lightman, A. P., and Eardley, D. M., Astrophys. J. Lett., 187, L21 (1974).
Parsignault, D. R., et al., Proc. Symp. on Fast Transient in X and gamma rays COSPAR/IAU, Varna, Bulgaria, May 30 (1975).
Pounds, K. A., Proc. Enrico Fermi Summer School, Varenna, July, 1975 (in the press).
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RAO, U., KASTURIRANGAN, K., SHARMA, D. et al. Observations of Cyg X-1 from Aryabhata. Nature 260, 307–308 (1976). https://doi.org/10.1038/260307a0
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DOI: https://doi.org/10.1038/260307a0
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