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Close Approach of 2023 BU
#1
CNEOS predicts that the newly discovered NEO 2023 BU will make a close approach on 2023-Jan-26 21:17 ± 02:22 UT at a distance of 0.00007AU. H=29.3 magnitude, V relative=9.33 km/sec, 'Rarity' = 2, Condition Code = 7.  This MP was discovered at MARGO, Nauchnij on 2023-01-21.

Using MPC's elements for February 25 2023 00:00 UT, ST4v predicts that this MP will reach a peak brightness of 16.1 magnitude on January 25 at 1800 EST when the NEO will be moving through Sagittarius at 14.2"/sec at 36.0k km distance. Close approach (to the nearest hour) is predicted to occur on January 25 at 1800 EST (2300 UT) when 2023 BU at 16.1 magnitude will be moving through Sagittarius at 14.2"/sec , 36.0k km distant but below the horizon as seen from Columbus, Ohio. Unfortunately ST4v predicts that it will not be observable with a 13" telescope under those conditions.

The Minimun Re occurs in daylight or twilight or the MP is below the horizon for North & South America, Europe & Australia so not a good shot at viewing it. It is getting very close though.

Since this NEO will get very close, parallax will affect the predicted positions, so you'll need to make charts for your location to get accurate positions for this object. Also, elements closer to the current date should be in the MPC's NEA datafile tomorrow. The elements for Feb 25 may reflect the earth's perturbtions on the orbit of this object, hence the difference between the CNEOS & ST4v predictied close approach time.

Good hunting.

Phil S.
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#2
CNEOS has updated the close approach info for 2023 BU after a second day's observations. The close approach is now predicted for  2023-Jan-27 00:17 ± 01:05 UT. The predicted distance is still 0.00007 AU. The condition code was reduced to 6. The MPC still lists the Uncertainty as 7.

Using MPC's elements updated for 2023 Jan 23 0000 UT, ST4v predicts that the close approach will occur on 2023 Jan 26 1800 EST (to the nearest hour) when 2023 BU is 11.4 magnitude, 28.4k km distant moving through Cancer at 104"/sec. The predicted close approach time is at the edge of CNEOS's error window. It will be easily visible from Europe, but North America is too far west. The close approach occurs in twilight here at 83°W.

Parallax will affect the apparent position, so you'll need to download the elements from the MPC & calculate an ephemeris for your observing location.

Good hunting,

Phil S.
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#3
I highly recommend using the latest osculating elements fetched from Horizons. Three days is just simply too far away for this small rock being perturbed as we write. I just reran this with those osculating elements. I'm coming up with closest approach to my yard of 13,190Km at Jan 26, 18:26:22CST.

I get closest approach at 9955 km (center to center) at 00:16:08 UTC on 27 Jan, over 51° 15' S, 116° 28' W (southern Pacific ocean). Moving at 129'/min. Over 2°/minute!

With a phase % of ~11, it might only get to 16th. It will be interesting to keep track of as more precision observations are made.

Right now, I'm seeing 42 obs over 3 days with elements for EPOCH 2459967.5 ! 2023-Jan-23.00 (TDB)

I'm curious where you are seeing magnitude 11.4 and close approach of 28.4k km distance?

Use the osculating elements generated by Horizons
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#4
CNEOS has updated the close approach some more. The close approach is now predicted to occur at  2023-Jan-27 00:26 ± 00:10 UT at 0.00007 AU (9.977k km). The condition code is 5.

Using MPC's elements updated for 2023 Jan 24 0000 UT, ST4v predicts that the close approach will occur on 2023 Jan 27 0035 EST when 2023 BU is 12.4 magnitude, 28.71k km distant moving through Lepus at 28.7"/sec. Here's the Object Info data at ST4v's close approach:     

The positions predicted using MPC's osculating elements are changing drastically as the elements are updated each day as the notes in the posted OI illustrate. The perturbations as 2023 BU approaches are really bending the orbit.

BMD, your predictions match CNEOS very well. It will be interesting to see what the predictions look like tomorrow.

Phil S.
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#5
CNEOS has updated the close approach for this NEO as 2023-Jan-27 00:29 ± < 00:01 UT at 9.967k km distant. The Condition Code is 3.

Using MPC's elements updated for 2023 Jan 26 0000 UT, ST4v predicts that the close approach will occur on 2023 Jan 27 0151 EST when 2023 BU is 12.7 magnitude, 26.941k km distant moving through Eridanus at 18.6"/sec when it is below the horizon in Columbus, Ohio.

Those trying to view this NEO should use the elements provided by HORIZONS for a time closer to the Minimum Re distance. The osculating elements seem to be changing too fast to provide an accurate position even if only 1 day from the minimum distance. The MPC has elements for the epoch 2023 Jan 27 0000 UT on their website, but I don't know how to get SkyTools to use that data file.

Phil S.
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#6
Greg provides the instructions at https://skyhound.com/forums/showthread.php?tid=2419

Just make sure to use one of the created osculating element sets that is closest to your time of observation. If my observation was going to be at 5:00CST on Jan 27, I would use these for 2023 BU:

2459971.958333333 = A.D. 2023-Jan-27 11:00:00.0000 TDB
EC= 1.490763600833533E-01 QR= 9.843185710306437E-01 IN= 4.986999775406508E+00
OM= 1.264165899146150E+02 W = 3.572715018591875E+02 Tp= 2459968.943047789391
N = 7.922029206293838E-01 MA= 2.388718014515821E+00 TA= 3.261689265599356E+00
A = 1.156764866853463E+00 AD= 1.329211162676283E+00 PR= 4.544290239601612E+02

You will need to fill in the name, magnitude - H & G. So remember what is in the data box b4 you paste.
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#7
BMD, I was referring to the NEO elements file from the MPC that has the elements for all of the NEOs for the epoch one day in the future. That would update all of the NEO elements to 2023 Jan 27 0000 UT if I could figure out how to have ST4v use that file instead of the one for Jan 26 or Today's Epoch.

Phil S.
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#8
I guess I thought you were only interested in BU. If so, copy/paste these in the editor. It will change the epoch to Jan 27 00:00TDB.

2459971.500000000 = A.D. 2023-Jan-27 00:00:00.0000 TDB
EC= 2.756925744419778E-01 QR= 8.483430811443597E-01 IN= 1.465011563544448E+00
OM= 3.062218187912473E+02 W = 2.491715848292417E+02 Tp= 2460025.281447667163
N = 7.775551406529739E-01 MA= 3.181819588945647E+02 TA= 2.910516346902909E+02
A = 1.171247251111333E+00 AD= 1.494151421078306E+00 PR= 4.629896726008136E+02
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#9
I try to avoid using the MP DB's Edit functions. I've messed up the DB too many times in the past  Big Grin. Generally the download of the MPC's 'NEAs at Today's Epoch' download button gets all of the NEOs at one time (~30,000 objects).

2023 BU was a special case because it got so close that the osculating elements from MPC never gave an answer for the approach time & distance that matched CNEOS's values. Even the MPC elements for 2023 Jan 27 0000 UT that I just downloaded were slightly in error. The latest elements predicted that it attained 9.7 magnitude! That occurred in twilight & below my horizon. 

Phil S.
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#10
Phil,

There is no reason to suspect that using the Edit function has caused any of the problems you have had, and even if they had, they are fixed now. I use the Edit function all the time without any trouble.
Clear skies,
Greg
Head Dude at Skyhound
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