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D. J. Tholen, R. J. Whiteley (Institute for Astronomy, University of Hawaii)
Observations at solar elongations of less than 90 degrees are required to find NEOs with aphelion distances of less than or equal to the Earth's heliocentric distance. At the time of this writing, we have imaged approximately 20 square degrees of sky with the University of Hawaii 2.24-m telescope and 8192x8192 mosaic CCD camera. During our 1997 August run, we discovered 1997 QK1, a potentially hazardous Apollo-type asteroid with an estimated diameter of about 400 meters. During our 1998 February run, we discovered 1998 DV9, another potentially hazardous Apollo-type asteroid with an estimated diameter of 900 meters, as well as 1998 DK36, which appears to be the first known object with an orbit entirely inside, but with an aphelion nearly tangent to, the Earth's orbit. Such objects represent an impact hazard, but will not be found by opposition search techniques. Following-night recovery observations for 1998 DK36, made at half the non-sidereal rate for the asteroid, resulted in the discovery of three other fast-moving objects in only 1 square degree of sky coverage. The higher discovery rate is apparently related to the detection threshold, which was fainter for objects with motion similar to that of 1998 DK36. Unfortunately, those three objects were lost due to a camera failure that prevented observations the following night. We will also report on additional results from another run in August.