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W. F. van Altena, C. D. Bailyn, T. M. Girard, D. Rabinowitz (Yale U.), R. L. Branham (CRYCIT, Mendoza, Argentina), M. Hicks (JPL), C. E. Lopez (UNSJ, San Juan, Argentina)
We describe an ongoing program dedicated to the observation of NEOs found by the northern discovery programs and whose tracks carry them into the Southern Hemisphere. We are observing the NEOs, to determine their positions, compute improved orbits and submit them to the Minor Planet Center over the Internet. Alerts of needed observations are monitored on relevant Web pages and e-mail messages from our collaborators at the northern discovery programs. The observations are made at the Cesco Observatory at El Leoncito, Argentina with the 0.5-meter double astrograph and/or at CTIO with the 1.0-meter YALO telescope, depending on the magnitude of the NEO and the photometric requirements for the specific NEO. The double astrograph at El Leoncito observes simultaneous CCD B and V photometry and astrometry for those NEO’s brighter than 20, while the YALO observes those brighter than 21.5. YALO also provides simultaneous V and IR photometry and astrometry. All YALO observations are ftp’d to San Juan for astrometric reduction and then a revised orbit is computed from the new and existing observations in Mendoza and a decision is made to retarget our observations if necessary. If so, the El Leoncito and/or YALO observers are notified and provided with an improved ephemeris. The final positions and photometry are then forwarded to the MPC, MPEC and our collaborators. To date, we have reported the positions of over 2000 asteroids, 61 comets and 142 NEOs.