Evidence accumulates for a black hole in Cygnus X‐1

Within the past year many observers have become convinced that Cygnus X‐1 contains a black hole. The most recent evidence, reported at the December meeting of the American Astronomical Society in Tucson, is from an x‐ray detector aboard a rocket; a group at the Goddard Space Flight Center reported seeing millisecond variations in intensity, suggesting a compact object. Other recent evidence has come from observations with the 61‐cm telescope at the Lick Observatory and from a group at University College London, who have an x‐ray telescope aboard the Copernicus satellite. As the evidence has mounted, so has the excitement. However, there are many holdouts taking a wait‐and‐see attitude.

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