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SGP4Standard General Perturbations Satellite Orbit Model 4
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References in periodicals archive ?
The accuracy of the SGP4 model is comparable to the GPS Almanac as shown in a paper by Kelso [26].
GNSS satellite positions in the sky can be calculated using the SGP4 orbital model and TLE data.
Crawford, "SGP4 orbit determination," in Proceedings of the AIAA/AAS Astrodynamics Specialist Conference and Exhibit, Honolulu, Hawaii, USA, 2008.
Kelso, "Validation of SGP4 and IS-GPS-200D against GPS precision ephemerides," in Proceedings of the 17th Annual Space Flight Mechanics Meeting, pp.
The BC is estimated by comparing the change in semimajor axis according to two TLEs to the change in semimajor axis due to drag computed by accurate orbit propagation using an initial state derived from the first TLE (if not stated otherwise, states are obtained from TLEs using SGP4 to convert the TLE to an osculating state at the desired epoch and subsequently converting the state from the TEME to J2000 reference frame).
The [B.sup.*] parameter in TLEs is an SGP4 drag-like coefficient and a BC value can be recovered from it: BC = 12.741621 * [B.sup.*] [31].
(6) filter out TLEs with negative [B.sup.*] as they cause incorrect SGP4 propagation.
Because of the relatively low fidelity of the TLEs and the lack of transparency of the Analytical Graphics Incorporated special perturbations orbit-determination algorithm and the way it compares to SGP4, though, the causality of the delta between the TLE and the element set created from the test data remains unknown but is probably a mixture of timing accuracy and algorithm mismatch.