Improved Angular Observations in Geosynchronous Orbit Determination

Abstract

How improved angular observations can aid in the determination of satelliteposition and velocity in thegeosynchronous orbit regime is studied. Raven, a new, automated, low-cost sensor being tested by the U.S. Air Force Research Laboratory, allows for angularobservationsof satellitesto be madewith a standard deviation ofapproximately 1 arc-s (which maps into approximately 170 m at geosynchronous altitude ); this is an order of magnitude improvement over traditional angular observation techniques. Simulation studies are undertaken to show how these angular observations can be used in the orbit determination process both as the only tracking data source and as a supplement to other tracking data sources, such as radio transponder ranges. Parameters varied in the simulation studiesincludethenumberofobservingstations,thedensity oftheopticalobservations,and thenumber of nights of optical tracking. The studies indicate that including the improved angular observations with traditional high-accuracy range observations produces a considerable improvement in orbit determination accuracy over the range observations alone. The studies also indicate that single site geosynchronous orbit determination is an attractive alternative when combining improved angular and high-accuracy range observations.