WE have detected an optical pulsar with frequency f = 1,968.629 Hz at the location of supernova 1987A in the Large Magellanic Cloud. The brightness of the pulsed light increased from magnitude 19 to 18 during a 7-h observation period starting on 18.1 January 1989 UT, in observations taken using the 4-m telescope at Cerro Tololo Inter-American Observatory. The frequency of the pulsar during this same period varied in a nearly sinusoidal manner, with an amplitude of 1.5 x 10-3 Hz and a period of 8h. If this is interpreted as the result of a binary orbit, it suggests that there may be a Jupiter-sized object orbiting the pulsar at a distance of 106 km. No significant pulsations were seen in data taken with the same detection system at the 100" telescope at Las Campanas Observatory on 31 January UT, indicating that the pulsar had dropped below our detection limit of magnitude 20. Significant second (2f) and third (3f) harmonics were also observed.

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  1. Mt Wilson and Las Campanas Observatories, Pasadena, California, USA

    • J. Kristian
  2. University of California Lawrence Berkeley Laboratory, Berkeley, California, 94720, USA

    • C. R. Pennypacker
    • , D. E. Morris
    • , R. A. Muller
    • , S. Perlmutter
    •  & T. P. Sasseen
  3. Los Alamos National Laboratory, PO Box 1663, Los Alamos, New Mexico, 87545, USA

    • J. Middledrtch
  4. Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, 1353, Chile

    • M. A. Hamuy
    •  & W. E. Kunkel
  5. Institute of Theoretical Science, University of Oregon, Eugene, Oregon, 97403, USA

    • J. N. Imamura
  6. Mt Stromlo & Siding Spring Observatories, Australian National University, ACT, 2606, Australia

    • S. J. Rawlings
    •  & I. R. Tuohy
  7. University of Toronto, Toronto, Ontario, Canada, M5S 1A1

    • I. K. Shelton
  8. NASA Ames Research Center, Space Science Division, Moffett Field, California, 94035, USA

    • T. Y. Steiman-Cameron
  9. California Institute of Technology, Pasadena, California, 91125, USA

    • R. Lucinio


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