Astrometric Calibration for Wide-Area Space Surveillance Sensors

A technique for the real time reduction of the astrometric position of a moving object detected against a background of reference stars has been developed for satellite and asteroid measurements. The technique has been implemented for the Lincoln Near Earth Asteroid Research (LINEAR) system and is currently being adapted for the space surveillance application and installed in the Moron Optical Space Surveillance (MOSS) System. The first iteration assumes a simple a priori focal plane model with a predetermined pixel scale with no focal plane rotation. A physical focal plane model is determined using multi-variable singular-valuedecomposition (SVD) which includes linear offset, x and y scale, rotation, decentering, and a third order polynomial radial distortion characteristic of the GEODSS Main telescopes. Typically, a focal plane model can be determined with a residual error of approximately 0.5 arcsec root mean square (rms). 271648 astrometric observations reduced between June to December 1999 with the technique for the LINEAR program have produced a mean systematic error of less than 0.052 arcsec and rms errors in each axis of 0.62 arcsec. Over 80% of all observations have errors of less than one arcsec. The technique has been adapted for use in the MOSS system, where it has improved metric accuracy to better than the arcsecond level and increased metric tracking throughput by eliminating the need for the system to observe a separate calibration star at the end of each track.