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Click on "DSS from Internet", and there will be a slight pause while the downloading function starts up. After a second or so, the hourglass cursor will turn back to an arrow, and the actual downloading of the image will take place in the background. This is a good thing, since the images can take a while to download. The images are requested and retrieved from an STScI (Space Telescope Science Institute) server, and the large size of the image files combined with the slow response of the server can combine to cause it to take a few minutes to actually fetch the image. Because it is processed in the background, you can continue to do other things in Guide while this is going on. Once it's done, though, the chart will refresh and the image will appear. If you have a dial-up connection, you should find that if you aren't connected at the time you click on "DSS from Internet", the standard Windows connection dialog should appear and dial in to your ISP. In some cases, this fails to happen. If so, you will have to make sure that you're connected to the Internet before selecting this function. By default, the download will be from the DSS-1, the "original" DSS based mostly on photographs made in the 1950s. More recently, STScI has been creating the DSS-2, from more recent data. Both 'R' (red-sensitive) and 'B' (blue-sensitive) plates have been scanned in, and you can select the sort you prefer (or stick with the original DSS-1). DSS-2 was scanned at slightly higher resolution; be warned that this means larger downloads. Also, DSS-2 is not available for the entire sky; in particular, asking for DSS-2 B will frequently result in an "image not found" message. It can be interesting to first download, say, a POSS red image, then change the "Normal" drop-down box to read "Blue overlay", and then download a POSS blue image. The result isn't quite a true-color one, and adjusting the contrast of the two images to match passably well can be difficult. But it does cause strongly-colored objects to become apparent. 17b: DOWNLOADING STAR DATA FROM THE INTERNET In recent years, several new large star catalogs have become available. One, UCAC-3, is the base star catalog used in Guide. Other catalogs cover stars to a deeper magnitude limit, though usually offering less data (and of lower accuracy) than UCAC-3. These catalogs are far too large to fit on the Guide DVD, but you can access portions of these catalogs for particular parts of the sky via the Get Star Catalog Data submenu: Get A2.0 from CD-ROM... Get B1.0 from Internet Get 2MASS from Internet Get GSC-2.3 from Internet
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