A simple astrometry function has been added to SatCal. You can now load pictures with satellite trails on them. Once loaded a picture will have to be initialized by clicking on three stars and entering the respective sky coordinates. (This is the bottleneck of the whole operation as it has to be done manually.) Once initialized you can then click on the endpoints of a satellite trail and have SatCal calculate an approximate (circular) orbit fitting the trail as well as checking which objects of the currently loaded TLE file (typically the Spacetrack ALL_TLE) might fit the trail. (This may have to be repeated checking the reverse direction as well unless you already know whether the satellite was moving left to right or right to left along the trail). The candidate objects thus found can then be displayed to move across the picture just as they otherwise would move across the standard world or sky map and you can see how the objects fit the trail. Just don't get too excited about this. If you want to check the identity of a single satellite you saw it is normally much faster to just check which objects passed the approximate direction at the right time rather than going through the process of identifying three reference stars. But there are three cases where this new feature could be useful: You have multiple trails on a picture and have to sort out the various satellites. You take a series of pictures of the same part of the sky. If you can use the same reference stars you have to supply the respective coordinates just once. On successive pictures it is enough to just click on the reference stars as the last set of coordinates will have been remembered. Initializing these follow-on pictures is thus a matter of seconds. You want to investigate flares. In this case you typically know the identity of the satellite and can load it directly and have it move across the picture while displaying the orientation of the surface which would cause a maximum flare at that moment. Checking it along the trail you can then have an idea which surface might have flared. Anybody interested can download a Linux or Windows Version of SatCal 11.0 from http://www.aaw-darmstadt.de/websystem/_main.php?page=download.php Windows users might encounter a problem when trying to load JPG files. I haven't been able to figure out why because it runs correctly on my own Windows system as well on all the different Linux distributions I've tested it. If you are affected by this problem you would have to convert the JPG file into a PNG file first which can be done by almost any image processing program. Gerhard HOLTKAMP Darmstadt, Germany _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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