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Where can I find current minor planet elements?
#1
Hi Greg,

I downloaded a large amount of data for minor planet orbital elements (400k+) recently, but the elements are for epoch 26/27 Apr 2019. ST4i now considers these elements to be out of date. When I downloaded more data from the Minor Planet Center (MPC) today, the epoch was still 26/27 Apr 2019. I noticed that the epoch for your Current Minor Planets file is for epoch 4 Aug 2019 (based on the Object Info for several of them).

Where can I find more current orbital elements or are we stuck until the MPC gets things sorted out again?

Thanks,

Phil S.
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#2
Hello,

The Minor Planet Center publishes new epochs at intervals that I feel are much too long, but SkyTools has been adjusted to accommodate it. So if you are using the latest version, the problem is likely that the recent server loss at the MPC has delayed publishing their files at a new epoch. The last time I looked, the comets were still using May 15 as the epoch, which is pretty unacceptable as far as I'm concerned. I know they have other priorities, but they are not currently getting this part of their job done, which many observers rely upon, often those that the MPC in turn relies on for their raw data.

To answer your question, download the ASTORB database instead. It is always published with a very recent epoch. To do so, simply make the ASTORB choice on the download dialog. The only disadvantage to ASTORB is that it contains elements for many minor planets that have since been lost, which swells the size of the database.
Clear skies,
Greg

SkyTools Developer
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#3
Hi Greg,

Thanks for the additional info. I'm using ST4i v4.0e. I used the database cleanup function and reduced the number of minor planets in the 26/27 Apr 2019 epoch from 400k+ to 5k+. There are also a few (69) with elements for 12 Nov 2019.

I just downloaded the MPC's Bright Asteroids list. ST4i Added 0 objects, Updated 1 object and Skipped 796325 objects.

Downloading the ASTORB data for Numbered, Bright objects didn't provided updated elements, but downloading data for Numbered objects without checking the 'Bright' box has ST4i adding 150157 (and counting) objects. Hopefully the epoch will be more current than what's provided by MPC.

Thanks again,

Phil S.
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#4
Hi,

There is no need to clean up your database, unless you feel it is taking up too much space on your hard drive. Do you ever want to see where a minor planet was last spring? Or maybe in the field of an image you took last year? The older epochs are still valid, just for that time. If you set the date in SkyTools back to an earlier time, SkyTools will use the elements from the older epoch, and it will have an accurate position.

For bright minor planets, I presume that you have been downloading the bright ones via the current bright minor planets list, which would mean most are already in your database, and because they are in a list, they were not deleted when you cleaned up (for obvious reasons).

ASTORB uses the MPC data as the starting point, but computes elements the current epoch, usually the same day.

I have found when doing astrometry using Astrometrica, when we get several months away from the last epoch published by the MPC, that minor planets near opposition are often marked significantly away from their actual position. I mentioned this on the Astrometrica forum, but nobody else seemed to think it mattered. To me, it makes no sense. They really should publish at shorter epoch intervals.
Clear skies,
Greg

SkyTools Developer
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#5
Hi Greg,

ST4i v4.0e now says the there are '541128 minor planets at this epoch'. I still have 7206 for 2019 Apr 26. That should be sufficient  Smile .

Thanks again,

Phil S.
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