Canceled: DIX Planetary Science Seminar

Catalina Sky Survey (CSS) is a major survey of Near-Earth Objects (NEOs). CSS's G96 telescope was upgraded in 2016 and detected over 10,000 unique NEOs since then. We characterize the NEO detection efficiency of G96 and use G96's NEO detections from 2013-2022 to develop a dynamical model for NEOs (NEOMOD). We estimate there are 936+/-29 NEOs with absolute magnitude H < 17.75 (diameter D > 1 km for the reference albedo p_V = 0.14) and semimajor axis a < 4.2 au. The slope of the NEO size distribution for H = 25-28 is found to be relatively shallow (cumulative index ~ 2.6) and the number of H < 28 NEOs (D > 9 m for p_V = 0.14) is found to be (1.20 +/- 0.04)x10^7, about 3 times lower than previous estimates. Small NEOs have a different orbital distribution and higher impact probabilities than large NEOs. We estimate 0.034 +/- 0.002 impacts of H < 28 NEOs on the Earth per year, which is near the low end of the impact flux range inferred from atmospheric bolide observations. Relative to a model where all NEOs are delivered directly from the main belt, the population of small NEOs detected by G96 shows an excess of low-eccentricity orbits with a = 1-1.6 au that appears to increase with H (~30% excess for H = 28). We suggest that the population of very

small NEOs is boosted by tidal disruption of large NEOs during close encounters to the terrestrial planets. When the effect of tidal disruption is (approximately) accounted for in the model, we estimate 0.06 +/- 0.01 impacts of H < 28 NEOs on the Earth per year, which is more in line with the bolide data. The impact probability of a H < 22 (D > 140 m for p_V = 0.14) object on the Earth in this millennium is estimated to be 4.5%.