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'Out, damned spot.' (spot observed next to supernova 1987 disappears)

"Out, damned spot'

The incriminating spot that Lady Macbeth wanted to be rid of would not disappear. The spot that has perplexed astronomers lately--and been damned by some of them--seems to have disappeared, but its discoverers say it could come back again. This is the strange "companion' to the supernova 1987A, the bright object that suddenly appeared next to the supernova itself (SN:8/22/87, p.122).

The leader of the group that discovered the spot, Costas Papaliolios of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., says that although the spot had appeared in observations taken on March 25 and April 2, it was not present in observations on May 30 and June 2. At least one member of the audience, Nolan Walborn of the Goddard Space Flight Center in Greenbelt, Md., expressed doubt about the existence of the spot at any time. However, others expressed confidence in Papaliolios's observational technique.

Known as speckle interferometry, the technique uses computer analysis of thousands of images taken through a mask with seven pinholes. Scientists look for correlations that reveal details that turbulence in the atmosphere normally blurs.

Papaliolios maintains that the earlier observations were not spurious. The spot was really there, he says. It may have faded, or the location of the supernova during the May-June observations, which was much closer to the horizon than earlier in the year, may have made the spot harder to see. The group is currently analyzing observations made later in the summer to see whether the spot reappears.
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Author:Thomsen, Dietrick E.
Publication:Science News
Date:Oct 24, 1987
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