Uncertainty parameter

[2][3] The parameter is a logarithmic scale from 0 to 9 that measures the anticipated longitudinal uncertainty[4] in the minor planet's mean anomaly after 10 years.

Of these parameters, the time spanned by the observations generally has the greatest effect on the orbital uncertainty.

[8] Occasionally, the Minor Planet Center substitutes a letter-code (‘D’, ‘E’, ‘F’) for the uncertainty parameter.

The formula for cutting off the calculated value of U is For instance: As of 10 September 2016, Ceres technically has an uncertainty of around −2.6, but is instead displayed as the minimal 0.

648 000 is the number of arc seconds in a half circle, so a value greater than 9 would be meaningless as we would have no idea where the object will be in 10 years within the orbit.

The orbits of kilometre class NEAs are generally well known, though a few have been lost . However, large numbers of smaller NEAs have highly uncertain orbits. [ 1 ]
Function graph U(r)