Test Of Pulsar Navigation With Polar On Tg-2 Spacelab

Pulsar navigation, which utilizes pulsar observations to determine the position or orbit of a spacecraft, has raised interests of many countries. Several projects, such as NICER, have been proposed. POLAR on-board the TG-2 space station of China has worked for about half year and its main task is to measure the polarization of the gamma-ray bursts. POLAR can also detect the photons from pulsars due to its large effective area (about 200 cm(2)) and wide field of view (more than 2 pi Sr). In this work we report our first results testing pulsar navigation with POLAR observations. A new navigation algorithm has been used that combines the orbit dynamics and pulsar profile analysis. With 31-day-long observations of the Crab pulsar, the TG-2 orbit was determined successfully. The parameter values of the orbital elements are solved and the errors are estimated by bootstrap method. The errors with 99.7% confidence are: semi-major axis error of 7.0 m, eccentricity error of 0.00026, inclination error of 0.023 degrees Right Ascension of the Ascending Node (RAAN) error of 0.17 degrees, error for argument of perigee of 0.042 degrees and mean anomaly error of 0.042 degrees.