Speaker
Description
Many newly discovered near-Earth asteroids (NEAs) are small ($<$100 m), yet they still pose significant risks if they impact Earth. Therefore, continued research and observation are crucial for the small NEA population, where characterisation significantly lags behind discovery rates. Our program at the South African Astronomical Observatory (SAAO) utilises the robotic capabilities of the 1-meter Lesedi telescope, equipped with the Mookodi instrument (Erasmus et al. 2024), for rapid follow-up observations of newly detected NEAs.
Using automated scripts that continuously monitor NASA JPL’s Scout page, observations are scheduled in robotic mode, allowing data collection often within the same night of discovery—a crucial strategy given the rapid dimming of smaller NEAs as they move away from Earth. Since February 2023, we have observed approximately 230 NEAs, with an average absolute magnitude of 24.4, corresponding to a size of 30 to 80m depending on the albedo. Of all the asteroids we observed, 75% are under 100 meters in diameter, indicating that our strategy is successful in targeting the small NEA population, as is our goal for the program. Fifteen of the asteroids we followed up on have since been classified as potentially hazardous asteroids (PHAs).
This work presents findings based on multi-filter photometry and astrometric measurements collected in our program. Our astrometry has significantly contributed to the Minor Planet Center's orbital refinement for the submitted objects and collected g', r', i' photometry enables us to extract g' - r' and r' - i' colours, approximating spectral slope and aiding in determining the most likely taxonomic type (S, C, X, D, Q, and V-types for this project) of these NEAs based on the Bus-DeMeo Classification Scheme (DeMeo et al. 2009). Using the collected data, the compositional distribution of the small NEA population was determined and compared with previous studies.
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