Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

June 25, 1997
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

A GRB Host?
Credit: K. Sahu (STScI) et al. , WFPC2, HST, NASA

Explanation: Where do gamma-ray bursts (GRBs) originate? The most powerful explosions in the universe have recently been located with record accuracy. But do GRBs occur in galaxies or out alone in deep space? This picture taken with the Hubble Space Telescope of the field surrounding GRB 970228 might provide a clue. It appears to show an extended structure to the lower right of the GRB, which is identified with an arrow. Many astronomers speculate that this extended structure is a distant galaxy, as its colors and subsequent steady emission indicate. Other astronomers worry that the extended emission is variable and so cannot be a galaxy. Astronomers hoping for more cases to study were rewarded just last Monday with a new, well-located event: GRB 970616. The location of this burst was determined by an unprecedented collaboration involving the tandem use of NASA satellites Compton, Ulysses and Rossi.

Tomorrow's picture: A Close Encounter of the Stellar Kind

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
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&: Michigan Tech. U.