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T. Spahr (CfA), S. Chesley (JPL), J. Heasley, R. Jedicke (IfA)
The University of Hawaii's Pan-STARRS project will be a deep (R~24) wide field (~7 deg2) survey, with the goal of cataloging 90% of Potentially Hazardous Objects that are larger than about 300m diameter. It will be capable of surveying 6000 deg2/night enabling discovery rates almost two orders of magnitude greater than all existing surveys combined. No existing PHO follow-up facility can match the expected depth and discovery rate. With this in mind, it is important to select an intelligent discovery and follow-up cadence, not only for easy night-to-night linking, but also for high-quality orbit determination and efficient use of telescope time.
With these concerns, we simulated a typical set of Pan-STARRS NEO observations using the Bottke et al. [1] NEO model, 0".1 RMS astrometry, and standard horizon and magnitude limits for Mauna Kea. Various cadences were investigated, including 2, 3, and 4-night data sets, with each observation night separated by four days. In addition, we varied the number of observations each night between 2 and 3 visits, with visits separated by 30 minutes. The impact of these choices on preliminary orbit determination, post-fit element uncertainties, and sky-plane uncertainties was studied. These simulations indicate that 3 observations per night is largely unnecessary, and that orbit determination using only two nights of data is not acceptable for our needs. Pairs of observations spaced by 30 minutes, and 3 or 4 separate nights of data over the corresponding 8 or 12-night interval provide well-determined orbital elements and small sky-plane uncertainties.
[1] W.F. Bottke, R. Jedicke, A. Morbidelli, J.-M. Petit, B. Gladman, Science, 288, 2190-2194 (2000).
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.