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NEO processing in ST4
In light of the recent close encounter with 2023 BU, together with the fact I haven't done much with asteroids in ST at all, is there a tutorial or explanation here in the forum that someone can point me to regarding how to handle NEOs? Specifically, is there a correct way to regularly update the elements of a NEO to ensure you have the latest relevant data?

Hello Bob,

I'm going to copy this thread to the Observing Close Approaching Asteroid forum, which is very active. I'm sure the members there can give you some tips. This is a specialized kind of observing, with a lot of nuances, both inside and outside of SkyTools, but it is also very rewarding. You may also find it helpful to go back and look at some of the earlier threads.

Oh, and have a look at the post pinned at the top of this forum!
Clear skies,
Head Dude at Skyhound
Hi Bob,

The easiest way to get the most up-to-date elements for all of the known NEOs is to have SkyTools download them directly from the MPC. Select the Data->Minor Planets Menu option to open the MP DB, then Clk the 'Download/Import Data' button to open the Update dialog, then Clk the 'MPC NEA Today' button to download the MPC's elements for the known NEOs (currently >30k objects). SY4 will use these elements when calculating the positions of the NEOs. This covers 99% of the cases for close approaches. For really close approaches like 2023 BU you'll need to get better elements from the HORIZONS website like Bigmasterdrago does. HORIZONS can provide a data file with elements for multiple times during the pass.

Hope this helps,

Phil S.
Bob, since you're asking about NEOs, good to follow the advice given by Phil. He stays on top of those rocks rather well.
Get handy at updating the 'MPC NEA Today' data file. Get handy at using the Database Power Search Tool/Minor Planets.

Several resources I like to point folks to are:
1) The near earth close approaches page - -- you can get a simulation at close approach
2) A page maintained by Gideon van Buitenen of NEO approaches -
3) A good minor planet look up page where you can see the latest observations -
A good example is:

For planning an observation of a particularly close rock, we need to use Horizons to get an element set for the date/time when we want to attempt finding it. Start at You might end up with a table of hourly osculating element sets. Copy the set appropriate for your time near observing. I got this for rock 2023 BZ. Paste that into the edit elements. You will need to pencil in the name, H & G since it does not paste into the edit element page in SkyTools. You can then run an ephemeris in SkyTools and make IA charts with tracks.

2459971.583333333 = A.D. 2023-Jan-27 02:00:00.0000 TDB
EC= 5.188420897660417E-01 QR= 9.856744707724684E-01 IN= 5.721365068568084E-01
OM= 1.347775776240116E+02 W = 3.538652353051908E+02 Tp= 2459973.264840397052
N = 3.361516569739936E-01 MA= 3.594347586143283E+02 TA= 3.579131404952533E+02
A = 2.048546744858031E+00 AD= 3.111419018943593E+00 PR= 1.070945189563208E+03

I want to add that most rocks that are not excessively close, the import of 'MPC NEA Today' should work very well. Just beware that small rocks that interact with the Earth/Moon system may not be plotted to high precision. Therefore the use of an element file that has included perturbations is nice.
Thanks to everyone for the concise replies, especially for Greg pointing out the existing pinned post, which I should've picked up.

Sounds like a lot of enjoyment to be had.
The NEO 2023 BU was a special case. Since it passed within less than 10,000 km, the perturbations by earth changed the osculating elements so much from day to day, that the MPC's 'NEAs at Today's Epoch' file couldn't keep up with the alterations to the orbit. In one of the threads here from summer 2021 or 2022, BMD & I 'tricked' ST4 to have it plot positions for a single NEO with several different element sets at one time. It was pretty cool to see the object in several positions on the chart. Rather time consuming though & hazardous to your MP DB if you mess up. I recommend making a Backup before trying it.

Phil S.
Noted re backups. Thanks.

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