## AAS 99-200

## Satellite Tracking Using Ambient RF (STAR) Part 3: Calibration Methodology

#### M. Storz, C. Krinsky, W. Rezzonico, R. Racca

## Abstract

Like other satellite tracking systems, STAR can contain systematic biases, leading to the erros in the estimated satellite trajectories. For example, the transmitter positions given by the Federal Communication Commission are typically only accurate to a few hundred meters. Estimating and removing these biases is a cost-effective way to improve the accuracy of resulting satellite orbit predictions. This paper describes the algorithm used to estimate biases in transmitter (television station) location and related biases. It uses an iterative least squares approach. In the least squares fit, the root mean square of the residuals between the measured and the computed bistatic range is minimized. The computed values originate from highly accurate (5 meter) laser-ranged reference ephemerides. Testing using real data has shown that, given a sufficient amount of observations with accurate reference orbits with which to compare, this algorithm can significantly improve on the accuracy of the published transmitter positions. This tool promises to be useful for STAR sensor calibration.