Hi Greg,
I suspect we may be talking past each other on the MP elements. I recognize that the elements derived from the most recent observations will yield the most accurate positions & MPC is tasked with collecting the observations & providing elements for others to use, including we SkyTools users. Unfortunately the MPC only provides elements for Today's epoch not future epochs. Is that correct? Sorry if I'm wrong on that. I don't think BMD wants to compare positions calculated from different data sources, I think he wants to calculate multiple positions from elements at different epochs all at a specific time to compare where each element set places the MP.
The only source for elements at a future epoch that I'm aware of is HORIZONS which allows you to obtain elements for any time (within reason) that you chose. This feature seems very handy for the close approach scenario where the purturbations during the close approach change the elements constantly, thus a single element set becomes less accurate as the pass proceeds. I think what BMD would like to be able to do is to provide SkyTools with a group of element sets, for example 5 sets from HORIZONS with epochs spaced around the time of the close approach. Again, as an example, spaced at 3 hour intervals, with the middle one at the time of minimum Re. Then draw a chart at time, t=x and use each of the 5 element sets to calculate the MP's position on the chart. This would allow him to visualize the effects of the changes to the elements. He could also step the chart time forward through the pass to see how the predicted positions change. At each time the 5 element sets would calculate the 5 positions.
Granted this is a highly niche functionality, but SkyTools' excellent charting capability would really shine at this. It need not involve the MP DB at all, just the small group of elements for one object at several epochs. Calculations would be very fast.
I hope this makes sense, I'd really like to see how changing elements alter the predicted positions too. It would really highlight the importance of accurate elements. I think ST4 already has 99.9% of the code needed to do this (at least I hope so - you have enough on your plate already).
Phil S.
I suspect we may be talking past each other on the MP elements. I recognize that the elements derived from the most recent observations will yield the most accurate positions & MPC is tasked with collecting the observations & providing elements for others to use, including we SkyTools users. Unfortunately the MPC only provides elements for Today's epoch not future epochs. Is that correct? Sorry if I'm wrong on that. I don't think BMD wants to compare positions calculated from different data sources, I think he wants to calculate multiple positions from elements at different epochs all at a specific time to compare where each element set places the MP.
The only source for elements at a future epoch that I'm aware of is HORIZONS which allows you to obtain elements for any time (within reason) that you chose. This feature seems very handy for the close approach scenario where the purturbations during the close approach change the elements constantly, thus a single element set becomes less accurate as the pass proceeds. I think what BMD would like to be able to do is to provide SkyTools with a group of element sets, for example 5 sets from HORIZONS with epochs spaced around the time of the close approach. Again, as an example, spaced at 3 hour intervals, with the middle one at the time of minimum Re. Then draw a chart at time, t=x and use each of the 5 element sets to calculate the MP's position on the chart. This would allow him to visualize the effects of the changes to the elements. He could also step the chart time forward through the pass to see how the predicted positions change. At each time the 5 element sets would calculate the 5 positions.
Granted this is a highly niche functionality, but SkyTools' excellent charting capability would really shine at this. It need not involve the MP DB at all, just the small group of elements for one object at several epochs. Calculations would be very fast.
I hope this makes sense, I'd really like to see how changing elements alter the predicted positions too. It would really highlight the importance of accurate elements. I think ST4 already has 99.9% of the code needed to do this (at least I hope so - you have enough on your plate already).
Phil S.