Radio images

Radio astronomers often feel a bit hard done by because it is difficult to make nice pretty pictures. This has mainly been because radio telescopes have never had more than a few 'pixels', so making an image requires a raster scan. To build up an image like this takes a lot of time, so it doesn't really get done. However, when you connect several radio telescopes up as an interferometer, you can build up an image as the Earth rotates.

Last summer the National Radio Astronomy Observatory (NRAO) in the United States launched a competition to find the best images made with data taken using any NRAO instrument. These include the world's largest steerable radio telescope, the Very Large Array (VLA) and the Very Long Baseline Array (VLBA). The contest had 41 entries submitted by 21 different scientists from around the world. The top prize was USD1000 and was won by Aeree Chung of Columbia University (see image below). Although teh winning image looks like a selection of Cadbury's Roses (foil wrapped chocolates for those that don't know) it is actually a cluster of galaxies in the Virgo cluster. They are now seeking submissions for the second year of the competition.

The winning image (20x20 degˆ2 centered at RA=12h32m0.0s, Dec=10d300.0) shows the neutral hydrogen gas (HI, 21cm) distribution of 47 spiral galaxies in the Virgo cluster on the X-ray hot gas background (ROSAT, Bohringer et al. 1994). CREDIT: Image courtesy of NRAO/AUI and Chung et al., Columbia University

Posted in astro blog by Stuart on Thursday 10th Aug 2006 (01:28 BST) | Permalink
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