For those of you who like to keep a list of Spacetrack-independent sources of elsets here is a new entry: MetOp-A TLEs are now available directly from Eumetsat flight dynamics on http://oiswww.eumetsat.org/metopTLEs/html/index.htm (Java Script must be enabled for this page). What is special about these TLEs is that they come with a specified accuracy. Two sets are available: Short-Term TLEs are valid for a given 12 hour arc with an RMS-error of 300 m while Long-Term TLEs can be used for at least a week with an RMS-error of 600 m (and maximum error of 2 km). Checking the latest short-term TLEs against the latest Metop-TLEs from Spacetrack I found a difference along one revolution of between 0.3 km and 1.5 km. Checking Eumetsat long-term TLEs from a week ago against the new short-term TLEs also showed a difference of about 1 km. But propagating Spacetrack TLEs from a week ago showed an error of over 10 km. (I had been assured that there was no orbit maneuver for Metop during last week in which case the difference would have been significantly larger). Last year Eumetsat already started issuing state vectors once a week for their four geostationary Meteosats. TLEs derived from those state vectors are also relayed on www.celestrak.com/NORAD/elements/supplemental/ (and my guess is that the new Metop-TLEs will probably be listed there too one day). Gerhard HOLTKAMP Darmstadt, Germany ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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