Optical Observation, Image-processing, and Detection of Space Debris in Geosynchronous Earth Orbit

We report on optical observations and an efficient detection method of space debris around the geosynchronous Earth orbit (GEO). We operate our new Australia Remote Observatory (ARO) where an 18 cm optical telescope with a charged-coupled device (CCD) camera covering a 3.17-degree field of view is used for GEO debris survey, and analyze datasets of successive CCD images using the uniform linear motion detection method. In our operation, the exposure time of each CCD image is set to be 3 seconds, and the time interval of CCD shutter open is about 4.7 seconds. In the uniform linear motion detection method, a sufficient number of object candidates is taken from each image based on their shape and intensity, which includes not only faint signals but also background noise. We select 500 object candidates from each image in this paper (the number depends on the limit of computational resources). Then we search a sequence of sample objects showing the uniform linear motion in the successive 18 images. As a result, we detected about 300 GEO objects up to magnitude of 15 among 5 night data. We also identified the objects from the two-line-element (TLE) data catalogue publicly provided by the U.S. Strategic Command (USSTRATCOM). We found that a certain amount of the detected objects are not listed in the catalogue. We conclude that our ARO and detection method posse a high efficiency detection of GEO objects despite the use of comparatively inexpensive observation and analysis system. We also describe the image-processing specialized for the detection of GEO objects (not for usual astronomical objects like stars) in this paper.