Improving the Detection of Near Earth Objects for Ground Based Telescopes

Congress has mandated the detection of 90 percent of 140 meter diameter and larger Near Earth Objects (NEOs). While a dedicated satellite would be the preferred method of detection, ground-based telescopes are the current detection technology available. With current detection techniques, 140 meter diameter NEOs at 1 astronomical unit or more away from Earth are difficult to detect. In order to increase their detection, the methods of data collection and data analysis must be addressed. Detection of NEOs, to include but not limited to asteroids, comets, and satellites, using groundbased telescopes with Nyquist sampling and a matched filter for point source objects are investigated as a image processing method to increase detection rates. Computer simulations for a 1 meter diameter telescope with a 128-by-128 charge coupled device (CCD), one second integration, and a 20.7 visual magnitude point source object within the CCD field of view (FOV) were computed using MatLab code. The simulation results for Nyquist sampling with cross-correlation of a point spread function (PSF) and a threshold detector are compared to Rayleigh sampling with a threshold detector. For accurate PSF calculations, atmospheric seeing measurements at the time of data collection are necessary, so various atmosphere seeing values, from 10 cm to 20 cm, are simulated and compared. Nyquist sampling with PSF cross-correlation and a threshold detector is found to be an improvement over Rayleigh sampling with a threshold detector for atmospheric seeing parameters of 10 cm to 20 cm for all simulations. The improvement over Rayleigh sampling is increased as the atmospheric seeing becomes worse. The affects of incorrect measurement of the seeing parameter are also simulated and analyzed. Simulations for the NEO in varying locations within the CCD pixel FOV are computed and analyzed. Nyquist sampling with PSF cross-correlation is an improvement over Rayleigh sampling for all locations with the improvement increasing as distance from the CCD FOV center is increased. Computer simulations show that Nyquist sampling with PSF cross-correlation outperforms Rayleigh sampling regardless of position within the CCD pixel FOV and for all atmospheric seeing parameters between 10 and 20 cm in detection of point source objects at a telescopes limiting visual magnitude.