2021-10-09, 04:30 PM
Hi Greg,
Back when BMD & I were trying to use a set of elements for a close pass, I tried to input elements from HORIZONS at 6 hr intervals. ST4v (4.0j R2) would only keep the first one that I entered & entering a new one was ignored. It also seemed that after a new set of elements was entered, all of the precalcs used to speed up plotting on the charts got repeated each time. With my MP database this took some time & I ended up with the same epoch date anyway - a waste of time. Can't add an element set from the MPC for different times because they only provide their 'standard' epoch time, like 2021 July 4 or the NEAs at Today's Epoch as options. Trying to add elements directly into the MP DB was an old method that you thought was eliminated, but we wiley users tried anyway
.
Would it be feasible to use a set of 3 osculating elements pre-, at & post-close approach taken from the HORIZONS system & interpolate between them during the pass? It would complicate the ephemeris calculations, but since it's only needed for the object of interest, it shouldn't be time prohibitive. As noted above this is a very niche application, so understandibly not a priority. I don't know how well interpolation of positions calculated from 2 sets of elements would work. Possibly weighting the results based on the time difference between the element epochs & the time for the calculation could work.
Cool stuff,
Phil S.
Back when BMD & I were trying to use a set of elements for a close pass, I tried to input elements from HORIZONS at 6 hr intervals. ST4v (4.0j R2) would only keep the first one that I entered & entering a new one was ignored. It also seemed that after a new set of elements was entered, all of the precalcs used to speed up plotting on the charts got repeated each time. With my MP database this took some time & I ended up with the same epoch date anyway - a waste of time. Can't add an element set from the MPC for different times because they only provide their 'standard' epoch time, like 2021 July 4 or the NEAs at Today's Epoch as options. Trying to add elements directly into the MP DB was an old method that you thought was eliminated, but we wiley users tried anyway
.Would it be feasible to use a set of 3 osculating elements pre-, at & post-close approach taken from the HORIZONS system & interpolate between them during the pass? It would complicate the ephemeris calculations, but since it's only needed for the object of interest, it shouldn't be time prohibitive. As noted above this is a very niche application, so understandibly not a priority. I don't know how well interpolation of positions calculated from 2 sets of elements would work. Possibly weighting the results based on the time difference between the element epochs & the time for the calculation could work.
Cool stuff,
Phil S.