The MPC 2012 DA14 obsersvations for Feb 2013 are now showing signs of acceleration.
The latest least squares fit for position, velocity and acceleration has an rms angular deviation of about 3 asec. I used MPC's longitude and parallax constants for the observatories for the first time.
The fit now indicates a close approach at Feb 15, 2013 11:30 UT with a radial distance from the center of the Earth of 7.3 Earth radii. There may be more signs of acceleration as the asteroid approaches. The formula for the fitted position is X=X0+V0Δt+A0Δt2 with Δt=t-t0 and t0=6.388. Distance was measured relative to the Earth-Moon barycenter.
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