Asteroids

2021EU help

Last update: 2025-09-10 00:30 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.564

Aphelion (Q)

3.579

Eccentricity (e)

0.728

Inclination (i)

3.8

deg

Orbit period (P)

1089.1

Earth MOID

0.00013

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

61000.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

2.071584

1-sigma variation

0.002864

Unit

Eccentricity (e)

Value

0.727545

1-sigma variation

0.000472

Unit

Inclination (i)

Value

3.8388

1-sigma variation

0.0028

Unit

Long. of Ascending Node (Ω)

Value

157.8016

1-sigma variation

0.0012

Unit

Arg. of Perihelion (ω)

Value

268.8253

1-sigma variation

0.0044

Unit

Mean Anomaly (M)

Value

226.01040

1-sigma variation

1.30950

Unit

Perihelion distance

Value

0.564413

1-sigma variation

Unit

Aphelion distance

Value

3.578755

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.001421

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.049346

1-sigma variation

Unit

MOID

Value

0.000131

1-sigma variation

Unit

Orbit Period

Value

1089.0611

1-sigma variation

Unit

U parameter

Value

8.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	8.20085E-6	1.35177E-6	7.96207E-6	-3.30809E-6	-1.24584E-5	-3.75004E-3
e	1.35177E-6	2.22818E-7	1.31243E-6	-5.45259E-7	-2.05377E-6	-6.18131E-4
i	7.96207E-6	1.31243E-6	7.73123E-6	-3.21056E-6	-1.21001E-5	-3.64085E-3
Ω	-3.30809E-6	-5.45259E-7	-3.21056E-6	1.33631E-6	5.01870E-6	1.51270E-3
ω	-1.24584E-5	-2.05377E-6	-1.21001E-5	5.01870E-6	1.89768E-5	5.69690E-3
M	-3.75004E-3	-6.18131E-4	-3.64085E-3	1.51270E-3	5.69690E-3	1.71479E0

Date of computation: 2025-09-10 00:30 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

mag

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

1659

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

Computation parameters

As seen from:

Initial Date: *

Final Date: *

Output option:

One line per time step

Time step:*

* - these fields are required

Close Approaches for 2021EU from 1950 to 2125

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	0.0671647
EARTH	1961-08-31 12:55	> 1 mo	0.1245102	0.0140344	0.6014746
EARTH	1964-08-14 01:31	> 1 mo	0.1755149	0.0139257	0.6112312
EARTH	2018-03-07 05:41	> 1 d	0.1513716	0.0203802	0.0436647
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	0.0437953
MARS	2063-02-13 21:16	> 1 w	0.0423300	0.0274459	0.1643170
65 Cybele	2096-10-05 19:48	> 1 d	0.0127363	0.0084877	0.0951412
VENUS	2101-11-05 01:31	> 1 mo	0.0452693	0.0127027	0.4892134
EARTH	2123-02-16 05:37	> 1 w	0.1366080	0.0022586	0.2297740

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
44.17910458	54.87091537	0.00011023	MINIMUM
314.79682290	232.42789472	0.00457084	MINIMUM
359.09767490	323.09680769	0.42543770	SADDLE
359.05398588	143.01453000	1.57653938	SADDLE
179.85606819	144.17646988	2.56877242	SADDLE
179.85637474	324.18067036	4.56373943	MAXIMUM

Download:

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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Download Impactor Table as: