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Where is Pallas ?
Hi Greg,

Since I don't have as much information as you, I always end up making some assumptions (many of which are unwarranted, sadly). Carlo's the only other user that I recall who had the issue of an MP search pulling up the wrong MP, but I may have missed them. I haven't experienced that problem since you fixed the bugs. Thank you!

Not knowing what Carlo's ultimate goal is in searching for these MPs, it's hard to be sure how to offer help. If he's willing to download the full MPCORB file, he'll have most of his minor planet bases covered for several months. All he''ll be missing will be the newly added NEOs which can be obtained by downloading the MPC's NEAs at Today's Epoch datafile of ~34k NEOs.

I just thought that you might know why the epoch of osculation in the Current Bright and Interesting Minor Planets file was different than the MPC's old standard epoch. No big deal though. I'll check to see if the epoch changes the next time I download MPCORB.


Phil S.

In the thread above there has been some confusion about what data you were asking about. We were mostly discussing using the Bright Minor planet download from the MPC as compared to the other MPC sources. I didn't see a specific question that I understood to be specifically about my curated current minor planets list until just now.My Current Bright and Interesting Minor Planets uses data from ASTORB, which usually has data at more recent epochs. ASTORB used to be updated daily, which was awesome, but that went away some time ago. I have found significant differences in the position of main belt asteroids at opposition using the the data from the MPC. If I were them I'd be embarrassed. This is because their epochs are too far apart in time. Osculating elements are only really good for 90 days or so, especially for a main belt asteroid near opposition because they are relatively close and move quickly. For this reason I use the ASTORB elements instead for my list. They are available to everyone via the ASTORB download rather than the MPC.

You can easily tell where the elements came from. Open the Osculating Elements dialog and look at the Source field. It will say "Lowell" if it comes from ASTORB. Some of these will be out of date simply because they are no longer at opposition or bright enough to be included in my list. They aren't updated year round, only those in the current list get updated that month.

The Current list is there for casual observers so they have an easy way to add a bright asteroid to their list, and so that the NOLG will have enough data to suggest one or two. For people who want to observe asteroids and minor planets more deeply, the next level up is to download the Bright Asteroids from the MPC frequently.

The MPC gets funding for near earth asteroids, and that is a huge computational effort, so for your close approaches they can have have better data then ASTORB, and as you know JPL has even better elements than that. But for these bright man belt asteroids, they do have orbits that change, and the MPC just doesn't keep up with them.
Clear skies,
Head Dude at Skyhound
Hi Greg,

It looks like the epoch of 2024 Apr 1 13h54m40s is coming from the ASTORB data that you use to create the Current Bright and Interesting MPs Observing List each month. The MPC still appears to be using 2024 Mar 31 00h00m00s. That's the epoch that I got for 2024 GO today when I did a download of the elements for that newly discovered NEO that wasn't in the NEAs at Today's Epoch datafile yet. That solves that question. Thanks.

It's really bad that the MPC's elements are so bad that the predictions for the positions of main belt objects are inacurrate. That's sort of their primary job to keep that info up to date. At least it used to be. Their 'standard' epochs seem to be ~6 months apart (2023 Feb - 2023 Sep - 2024 Mar - 2024 Sep). I guess if they would switch to the next epoch about half way in between they would met your 90 day criterion, but just barely. Last year, the change from the February to the September epoch occurred in August rather than June-July.

Not much we can do, except complain I suppose. It is a massive computational effort.

Phil S.

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