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Zoom in on COSMOS

We are entering a great era when it comes to research tools for the study of deep space. But as new technologies create datasets we’re able to distribute globally, we need to consolidate our gains to make them available to broader audiences. That’s why the creation of a Web-based utility called COSMOS SkyWalker is such heartening news. Using it, huge and minutely detailed images from sources like the Hubble Space Telescope’s Advanced Camera for Surveys can be managed for presentations and study over the Internet.

The problem is no small one. Compare the Hubble Ultra Deep Field (UDF), which contains some 10,000 galaxies, to the Cosmological Evolution Survey (COSMOS), housing no less than 2 million. The image areas on these surveys are contiguous and made up of an extraordinary number of data pixels, some 1010 pixels for COSMOS. That kind of scale makes it all but impossible to show both size and detail at the same time. Shipping the complete COSMOS ACS image over the Internet, even in compressed JPEG format, is not feasible, nor are average PCs up to the challenge of displaying such imagery.

SkyWalker can be used to browse large images and view any part of them on the screen. Because it works with HTML and JavaScript only (integrated in Web browsers like Firefox and Internet Explorer), it is usable without specialized software. The key to SkyWalker is that images can be browsed without downloading them in their entirety, allowing the user to pan around in the image, moving a pointer and tapping several zoom levels for study and presentation.

Yes, there are dedicated scientific data viewers, but SkyWalker fills a notable gap, being useful for quick access to ACS imagery and especially handy for those of us who occasionally present live material to non-scientific audiences. The COSMOS ACS mosaic is now available on the SkyWalker site, but other datasets are being added. For background on how the software works, check Jahnke, Sanchez and Koekemoer, “Seeing the Sky Through Hubble’s Eye: The COSMOS SkyWalker,” avalable here.

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  • Ed Minchau July 27, 2006, 18:35

    It is readily apparent when there is a problem with one of the cameras or telescopes being used: check out RA149.9988 DEC 1.8395, and compare to RA150.5444 DEC 1.8569.