Asteroids

2021EU help

Last update: 2026-07-30 14:25 UTC

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.565

Aphelion (Q)

3.579

Eccentricity (e)

0.727

Inclination (i)

3.8

deg

Orbit period (P)

1089.0

Earth MOID

2.271E-6

U parameter

8.0

Next Earth close approach

Date

2123-02-16

Nominal distance (from Earth center)

0.13661

20436265

Maximum Brightness

24.3

mag

Risk

Object is in risk list

Physical Properties

Absolute Magnitude (H)

25.4

mag

Diameter

23 - 50*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-03-04

Observatory

Pan-STARRS 1, Haleakala

ORBIT VISUALISATION TOOLS

External links

Proper elements

Epoch

Near present day

Near middle of observation arc

Orbit properties

Epoch
Semimajor Axis
Eccentricity (e)
Inclination (i)
Long. of Ascending Node (Ω)
Arg. of Perihelion (ω)
Mean Anomaly (M)
Perihelion distance
Aphelion distance
Asc. Node-Earth Sep.
Desc. Node-Earth Sep.
MOID
Orbit Period
U parameter

Value

1-sigma variation

Unit

Epoch

Value

61200.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

2.071569

1-sigma variation

0.002868

Unit

Eccentricity (e)

Value

0.727464

1-sigma variation

0.000471

Unit

Inclination (i)

Value

3.8391

1-sigma variation

0.0028

Unit

Long. of Ascending Node (Ω)

Value

157.7904

1-sigma variation

0.0013

Unit

Arg. of Perihelion (ω)

Value

268.8362

1-sigma variation

0.0042

Unit

Mean Anomaly (M)

Value

292.10883

1-sigma variation

1.44674

Unit

Perihelion distance

Value

0.564577

1-sigma variation

Unit

Aphelion distance

Value

3.578562

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.000028

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.049009

1-sigma variation

Unit

MOID

Value

0.000002

1-sigma variation

Unit

Orbit Period

Value

1089.0496

1-sigma variation

Unit

U parameter

Value

8.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	8.22434E-6	1.35034E-6	7.96413E-6	-3.71216E-6	-1.21076E-5	-4.14898E-3
e	1.35034E-6	2.21711E-7	1.30763E-6	-6.09468E-7	-1.98813E-6	-6.81213E-4
i	7.96413E-6	1.30763E-6	7.71314E-6	-3.59350E-6	-1.17290E-5	-4.01771E-3
Ω	-3.71216E-6	-6.09468E-7	-3.59350E-6	1.67741E-6	5.45810E-6	1.87269E-3
ω	-1.21076E-5	-1.98813E-6	-1.17290E-5	5.45810E-6	1.78749E-5	6.10797E-3
M	-4.14898E-3	-6.81213E-4	-4.01771E-3	1.87269E-3	6.10797E-3	2.09306E0

Date of computation: 2026-07-30 14:25 UTC

Note: The ASCII file is in a format suitable for Orbfit input.

Download ASCII file:

Physical properties

Rotation Period
Quality
Amplitude
Rotation Direction
Spinvector L
Spinvector B

Rotational properties

Value

Unit

Source

Rotation Period

Value

Unit

Source

[-]

Quality

Value

Unit

Source

[-]

Amplitude

Value

Unit

mag

Source

[-]

Rotation Direction

Value

Unit

Source

[-]

Spinvector L

Value

Unit

Source

[-]

Spinvector B

Value

Unit

Source

[-]

Taxonomy
Taxonomy (all)

Taxonomy

Value

Unit

Source

Taxonomy

Value

Unit

Source

[-]

Taxonomy (all)

Value

Unit

Source

[-]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

25.353

Unit

mag

Source

[1]

Slope Parameter (G)

Value

0.15**

Unit

Source

[1]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[2]

Diameter

Value

23 - 50*

Unit

Source

[2]

Color Index Information

Color Index Information

Value

Unit

Source

Color Index Information

Value

Unit

mag

Source

[-]

Sightings

Sightings

Value

Unit

Source

Sightings

Value

Unit

Source

[-]

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Sources

No.	Name	Additional
[1]	ESA Aegis	ESA orbit determination and impact monitoring system
[2]	Estimation	Estimated from absolute magnitude

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

Unit

Source

[1]

Unobserved

Value

1967

Unit

Source

[1]

Normalized RMS of residuals

Value

0.429147

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-03-01.068207

Unit

Source

[2]

Last Observation

Value

2021-03-17.13482

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

38 (0)

Unit

Source

[1]

Radar Summary

First Observation
Last Observation
Delay (Discarded)
Doppler (Discarded)
Total Optical Observations (Discarded)

Radar

Value

Unit

Source

First Observation

Value

Unit

Source

[-]

Last Observation

Value

Unit

Source

[-]

Delay (Discarded)

Value

0 (0)

Unit

Source

[-]

Doppler (Discarded)

Value

0 (0)

Unit

Source

[-]

Total Radar Observations (Discarded)

Value

0 (0)

Unit

Source

[-]

Note: The ASCII file is in a format suitable for Orbfit input.

Sources

No.	Name	Additional
[1]	ESA Aegis	ESA orbit determination and impact monitoring system
[2]	MPC	Minor Planet Center: https://www.minorplanetcenter.net

Filters

Initial Date: *

Final Date: *

Normalised Only accepted

Max residual (arcsec):

* - these fields are required

Plot

Computation parameters

As seen from:

Initial Date: *

Final Date: *

Output option:

One line per time step

Time step:*

* - these fields are required

Note: Ephemerides requests are limited to a maximum of 1000 points and a final date not exceeding 2040/12/31 00:00.

Close Approaches for 2021EU from 1950 to 2126

Body	Date in UTC	Time uncert. in min	Nominal distance in au	Min. possible distance in au	Distance uncert. in au
MARS	1950-04-11 15:21	> 1 w	0.0206891	0.0201589	0.0671652
EARTH	1961-08-31 12:55	> 1 mo	0.1245102	0.0140344	0.6014791
EARTH	1964-08-14 01:31	> 1 mo	0.1755149	0.0139257	0.6112359
EARTH	2018-03-07 05:41	> 1 d	0.1513716	0.0203792	0.0436651
EARTH	2021-02-27 13:42	< 1 min	0.0206953	0.0206520	0.0000145
EARTH	2024-02-21 13:44	> 1 d	0.0931065	0.0005728	0.0437956
MARS	2063-02-13 21:16	> 1 w	0.0423300	0.0274459	0.1643182
65 Cybele	2096-10-05 19:48	> 1 d	0.0127363	0.0084879	0.0951406
VENUS	2101-11-05 01:31	> 1 mo	0.0452693	0.0127027	0.4892171
EARTH	2123-02-16 05:37	> 1 w	0.1366080	0.0022586	0.2297758
EARTH	2126-02-21 14:59	> 1 w	0.0682876	0.0018110	0.3246816

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
44.13832507	52.63427381	0.00000227	MINIMUM
314.76120166	230.22161198	0.00463732	MINIMUM
359.03077159	320.83447289	0.42543500	SADDLE
358.98464953	140.74777163	1.57693312	SADDLE
179.84528945	141.99453692	2.56844459	SADDLE
179.84575064	321.99906348	4.56379890	MAXIMUM

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MOID Plots

Click on the images to zoom-in and zoom-out

Level lines of the squared distance function

2021EU

Date in UTC	MJD	σ	Distance ± Width in RE	Stretching in RE	IP	Impact energy	PS
2056-08-29.110	72239.110	-1.168	0.84 ± 0.013	5.87E4	5.23E-6	2.56E0	-4.94
2056-08-29.116	72239.116	-1.098	0.37 ± 0.012	1.07E4	4.36E-5	2.57E0	-4.02
2078-02-24.477	80088.477	-1.033	0.27 ± 0.002	3.04E6	1.74E-7	2.55E0	-6.64
2093-02-23.854	85566.854	-1.173	0.37 ± 0.001	1.95E7	2.20E-8	2.52E0	-7.65
2123-08-29.982	96709.982	1.741	1.00 ± 0.013	6.63E4	1.47E-6	2.71E0	-5.96


Based on 38 optical observations (of which 0 are rejected as outliers) from 2021/03/01.068 to 2021/03/17.135.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.13 and 1.13 Earth radii.
Coordinates for LOV = EQU scaled= 1 second= F.
Aegis software version= 4.0, Date of computation=20250805 130500.123 UTC.

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