Hey all! I have been exploring some DP0.3 data and ran into something that I thought I would ask about. I created a dataset queried from SSObject and SSSource containing ~4.4 million objects, then filtered it down to only the rows containing objects with corresponding MPC identifiers (resulting in a dataset of about ~1.2 M objects). I was making some plots of heliocentric distance versus heliocentric velocities, and saw an outlier on my plots which upon inspection turned out to be Pluto. The odd thing was that Pluto’s heliocentric distance turned out to be >130 AU, which didn’t make sense to me. So I used topcat’s VO feature to obtain a dataset pulled directly from MPC (MPCORB, specifically) and matched objects from the DP0.3 dataset I was using to the MPCORB entries (about 434k objects matched IDs).
I then plotted e.g. the eccentricities provided for each object in the DP0.3 dataset with the eccentricities provided in the objects queried directly from MPCORB, and found there were many objects for which the eccentricities didn’t match. See below (x axis is the DP0.3 eccentricities, y axis is the MPC eccentricities for the same objects).
I repeated this exercise for inclinations and semi-major axes, and found similar results:
Do you have any thoughts on why there are discrepancies between the values provided in DP0.3 and MPC? I am wondering if this has anything to do with the assumptions of the DP0.3 simulation; e.g. for example assuming that some objects have only been observed a few times and thus their orbital elements might be “poorly constrained” from the perspective of the simulation, and thus wouldn’t match the accepted values? Not sure if that makes sense or explains what I am seeing here, but just thought I’d ask – thank you so much for any thoughts you might have on this!