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Possible Close Approach of 2016 WM1
#1
The NEO 2016 WM1 may make a close approach on the night of May 15-16. According to the CNEOS website the time of close approach is May 11 23:25 ±4 days 11:26 hours so who knows. CNEOS used elements of epoch 2016 Nov 22. The elements I used for the SkyTools predictions were downloaded from MPC's NEAs at Today's Epoch for 2022 May 11. I don't know if this NEO has been reacquired again or not. Hopefully, it will be spotted before it makes its next pass. Every day later that the pass occurs decreases the separation between earth & the NEO & a 4-day delay would really close the gap as the ST4v calculations indicate.

Here's the output of ST4v's ephemeris calculations near Columbus, Ohio for this object:     

I don't know how the MPC converts the 2022 Jan 21 standard epoch for NEOs to the epoch for today's date. I suppose I should investigate that further. If MPC's elements are a better representation of the current orbit than those used by CNEOS, then the ST4v predictions indicate a close approach is coming. 

Unfortunately, the moon will interfere. Greg may get a chance to observe this one at Mesa Redonda though.

Good hunting,

Phil S.
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#2
This rock is not even listed on the Spaceweather page. Probably due to the uncertainty/error of 4 days. It is showing close the 15th on the http://astro.vanbuitenen.nl/neos page. The most recent obs I've found was on 2016 11 24.15172 at mag 18.6V by Mt. Lemmon with an epoch of 2019-04-27.0. If using elements from the MPC (epoch Jan 21) and those from Lowell (May 1), I find the rock plotted 93° apart for current date. If I use the elements on the discovery page (epoch 2019-04-27.0), I get it only 2° from the MPC position. So, yea, I would say until we get one of the big observatories to sweep this lost rock up, we are sunk. +/- 4 days !! Ouch. Until it gets above us and/or outside our orbit in a few days, it may be difficult to pick up.
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#3
Hi BMD,

Check out the Orbit Viewer for this one at the CNEOS website. Step through the position in 1-day intervals & imagine that the NEO is 4 days behind the CNEOS's predicted position. Things get really close. Who to believe? As noted, CNEOS is still using the elements from 2016 Nov 22.

I did some checking at MPC & apparently, they do apply perturbations to their elements calculations. Here's the MPC's entry for this NEO:     

The description of the perturbation info is given on their website here: https://minorplanetcenter.net/iau/info/Perturbers.html

2016 WM1 uses the default perturbation settings shown here:

Some examples of coarse and precise indicators are:

  Coarse  Precise    Perturbers (Mercury-Neptune+...)

    M-c      08      Ceres, EM barycenter
    M-c      0E      Ceres, Earth, Moon
    M-p      16      Pallas, Earth, Moon    [NOT RECOMMENDED]
    M-p      18      Ceres, Pallas, EM barycenter
    M-p      1E      Ceres, Pallas, Earth, Moon
    M-v      38      Ceres, Pallas, Vesta, EM barycenter
    M-v      3E      Ceres, Pallas, Vesta, Earth, Moon
    M-e      78      Ceres, Pallas, Vesta, Eunomia, EM barycenter
    M-e      7E      Ceres, Pallas, Vesta, Eunomia, Earth, Moon
    M-h      39      Ceres, Pallas, Vesta, Hygiea, EM barycenter
The default for Minor Planet Center orbits will henceforth be h (DE403), M-v (coarse) and 38 or 3E (precise, depending on whether the object is an earth-approacher or not). Additional perturbers will be added as necessary.


Hopefully this means that the MPC's elements include perturbations & that they're more accurate than what CNEOS is showing using elements from 2016.

There sure is a lot to learn about these objects. Very fascinating. I have no idea where this thing will be in 4 days.

Phil S.
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#4
It's good that the MPC does that but the position would be only accurate for the epoch date (Jan 21). Any ephemeris that we produce using that epoch is only accurate for a short time if the software does a 2-body computation (common amateur astronomy packages). Using Horizons or software that uses gravitational perturbations of the solar system will give better positions. But until this rock is recovered, all bet are off!
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#5
Hi BMD,

I used elements from the MPC's NEAs at Today's Epoch for 2022 May 10 as shown in the OI dialog of the head post. The epoch is 2022 May 11 0000 UT, so close to the current date. That's the advantage of downloading the MPC file for NEAs at Today's Epoch. Plus, it looks like they do the perturbation calculations, too.

In checking out the MPC site I found that they also produce files of elements for NEOs at today's date and every date ±15 days. Where these are located on their site, I don't know. I think having ST4v download the file for Today's epoch is sufficient for what I do, but to actually observe these objects may require better accuracy.

Did you check out the Orbit Viewer section on the CNEOS website? It's neat to watch the MP approach the earth's position.

Phil S.
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#6
Yes, I've played with the new "viewer" recently. A great way to quickly visualize the orbit close pass.
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