Another screamer 2021 UA1 on Oct 24

[PMSchu]

We missed another fast mover on the evening of 24 Oct 2021 @2300 EDT. 2021 UA1 was calculated to be moving at 2.95°/sec through Cepheus. Here's a chart in the IA: [attachment=2083]

It's moving so fast that ST4 had to include the time to the second on the tick marks & the whole text string didn't fit on the label . What's shown as 2h should be 22h. Minimum Re was 11.1k km.

The osculating elements were downloaded from the MPC's NEAs at Today's Epoch using ST4v on Oct 26.

Talk about a close shave.

Phil S.

[bigmasterdrago]

Another one of those "Whizzers" that got nabbed after close approach! Apparently, it was picked up by the Zwicky Transit Facility (Palomar Mountain) about 3 hours after it went screaming over my yard (25 Oct 3:06UT), moving 3.6°/minute (3.7'/second), 56° below my horizon in the far south!!

From a location just 17 miles east of me, it appears to have possibly occulted a 10th mag star at 25 Oct 03:06:01.72UT.  If I could have seen thru the Earth.



Phil, see what you get for the RA & DEC if viewing it from 30 28 37.1N 95 15 55.2W at 3:06:01.72UT October 25, 260' elevation. Just curious.

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We missed another fast mover on the evening of 24 Oct 2021 @2300 EDT. 2021 UA1 was calculated to be moving at 2.95°/sec through Cepheus. Here's a chart in the IA: 

It's moving so fast that ST4 had to include the time to the second on the tick marks & the whole text string didn't fit on the label . What's shown as 2h should be 22h. Minimum Re was 11.1k km.

The osculating elements were downloaded from the MPC's NEAs at Today's Epoch using ST4v on Oct 26.

Talk about a close shave.

Phil S.

Closest I've seen in a very long time!!  14,000Km!

[PMSchu]

Hi BMD,

Here are the ephemeris & IA chart for 2021 UA1 that you requested. The elements are epoch 2021 Oct 26.

Phil S.

[bigmasterdrago]

I suspect that your elements (epoch Oct 26) are too far away for working out the position correctly for Oct 24th . I appreciate the help.

[PMSchu]

What elements would you like used? If you provide them, I'll see what they predict in ST4v. For an object that close would any set of osculating elements be accurate enough? I had some older elements but they were replaced when I downloaded the data for NEAs at Today's Epoch from the MPC earlier today.

Phil S.

[bigmasterdrago]

Even using software that uses multi-body calculations/perturbations plots this very small rock about 10' NE of the latest Horizons location.

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Phil, see what you get using these from Horizons:

2459512.625000000 = A.D. 2021-Oct-25 03:00:00.0000 TDB
EC= 4.582878123801915E-01 QR= 5.689222683587210E-01 IN= 9.342199248570733E+00
OM= 2.115919489588242E+02 W = 6.883927443722253E+01 Tp= 2459450.104382985737
N = 9.157513854056469E-01 MA= 5.725334164740746E+01 TA= 1.111880955880744E+02
A = 1.050229773966262E+00 AD= 1.531537279573803E+00 PR= 3.931197983834139E+02

Only run the ephemeris for an hour with 5 minute steps. See what you get for my location using the lat & long in post #2.

Big thanks!

[PMSchu]

I can't get ST4v to accept those elements in the format provided. I used to be able to paste elements into the MP DB in that format. Every time I try to Copy/Paste the values aren't correct. How are you adding elements from HORIZONS now?

Phil S.

[theskyhound]

I tried a copy paste of the elements above and it worked ok. Be sure not to include any extra lines or spaces.

[PMSchu]

I couldn't get the elements to update. Tried the Read File option & the Edit Elements option in the MP DB itself. The epoch of the elements for 2021 UA1 remains 2021 Oct 27 that I downloaded from MPC yesterday.

Also the Help for the MP data download says the file format for the Read File option is either SkyTools or MPCORB format, but the dialog has SkyTools & ASTORB format. Is ASTORB=MPCORB format?

Phil S.

[theskyhound]

I'm not following at all... sorry. I thought we were talking about copy/pasting the elements? There is no support for Horizons format in the Read File option. Phil, please sepcify exactly the steps you are talking and what happens.

I also don't understand what dialog says something about the formats??? Sorry. I'm lost.