pbirtwhistle Nov 10, 2014
Hi Bill,
I'm having trouble trying to reconcile the ephemeris positional uncertainty info given by FindOrb to what I think should be similar values given in the MPC's Ephemeris Service and NEODyS Obs Prediction pages.
If I take a one opp object, e.g. 2009 VZ, get all the astrometry from the MPC's Orbits/Observations database, generate a full step perturbed solution in FindOrb and then generate an ephemeris, the PA (in this case for 2009 VZ for today) is given as 128. Both the MPC and NEODyS show the positional uncertainty extending in PA approx. 50 deg / 230 deg.
I've checked this with a number of objects and have yet to find one where FindOrb matches up well. Quite often the FindOrb value is closer to being perpendicular than in line with MPES/NEODyS?
Any ideas? I'm using the current production FindOrb that's reporting version as 27Jul2014 but with a modified date of 08Aug2014 in the find_o32.zip download file.
Peter
J95