Friday, September 19, 2008

Record distance for gamma ray burst: redshift 6.7!

GROND, the Gamma-Ray Burst Optical Near-IR Detector sitting behind an old 2.2-meter telescope in Chile, on September 13 has found the most distant gamma-ray burst ever detected. Alerted by the Swift satellite, the unique instrument taking images in 7 different colors obtained a rough redshift only minutes later, which was confirmed 1½ hours later with the Very Large Telescope. At a redshift of 6.7 GRB 080913 occurred less than 825 million years after the Universe began, and the star that popped off this shot seen across the cosmos died when the Universe was less than one-seventh its present age. The most distant GRB before had a redshift of 6.3 and was was 70 million light years closer to us. • And another astrophysics record of some importance: the least luminous galaxy is the dwarf Segue 1, full of dark matter.

In other news a sensational new image composite of the 1 August TSE has been released by M. Druckmüller, showing coronal streamers for 20 solar radii and many stars, including the Beehive cluster, in the background. • Tonight the Moon once more occults the Pleiades, in Europe only on Saturday morning. • The evening planets as seen from Oz in mid-September.

• Comet Lulin on the 17th - and new page on all comets in the sky right now and how easy or hard they are. (This and this catalog are excellent additions.) • Two bright sun dogs today. • A political article on light pollution as an overlooked environmental problem. • The ISS transiting the Moon and in much detail. • And ... it's alive: ISEE 3 alias ICE, the first spacecraft to visit a comet. Which was in 1985, already in an extended mission!

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