Asteroids

2021AB help

Last update: 2025-11-24 16:53 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.882

Aphelion (Q)

4.145

Eccentricity (e)

0.649

Inclination (i)

1.4

deg

Orbit period (P)

1455.1

Earth MOID

0.00392

U parameter

8.3

Next Earth close approach

Date

2028-12-24

Nominal distance (from Earth center)

0.11026

16495386

Maximum Brightness

22.8

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

25.1

mag

Diameter

25 - 60*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-01-02

Observatory

Catalina Sky Survey

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

2.513066

1-sigma variation

0.008264

Unit

Eccentricity (e)

Value

0.649199

1-sigma variation

0.000937

Unit

Inclination (i)

Value

1.4252

1-sigma variation

0.0177

Unit

Long. of Ascending Node (Ω)

Value

293.0991

1-sigma variation

0.1272

Unit

Arg. of Perihelion (ω)

Value

213.4317

1-sigma variation

0.2538

Unit

Mean Anomaly (M)

Value

72.22469

1-sigma variation

0.16277

Unit

Perihelion distance

Value

0.881587

1-sigma variation

Unit

Aphelion distance

Value

4.144546

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

2.159902

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.041311

1-sigma variation

Unit

MOID

Value

0.003916

1-sigma variation

Unit

Orbit Period

Value

1455.1387

1-sigma variation

Unit

U parameter

Value

8.3

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	6.82900E-5	7.73910E-6	-1.46217E-4	1.05141E-3	-2.09740E-3	1.34509E-3
e	7.73910E-6	8.77050E-7	-1.65703E-5	1.19154E-4	-2.37692E-4	1.52435E-4
i	-1.46217E-4	-1.65703E-5	3.13071E-4	-2.25123E-3	4.49080E-3	-2.87999E-3
Ω	1.05141E-3	1.19154E-4	-2.25123E-3	1.61882E-2	-3.22924E-2	2.07094E-2
ω	-2.09740E-3	-2.37692E-4	4.49080E-3	-3.22924E-2	6.44179E-2	-4.13120E-2
M	1.34509E-3	1.52435E-4	-2.87999E-3	2.07094E-2	-4.13120E-2	2.64940E-2

Date of computation: 2025-11-24 16:53 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

25.119

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

25 - 60*

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

[-]

Download this part as:

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

1894

Unit

Source

[1]

Normalized RMS of residuals

Value

0.646057

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-01-01.17539

Unit

Source

[2]

Last Observation

Value

2021-01-03.757086

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

55 (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

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 2021AB 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
EARTH	1958-02-16 17:35	> 1 w	0.1313945	0.1302744	0.0009535
EARTH	2013-04-13 10:25	> 1 d	0.0984275	0.0233835	0.0603730
EARTH	2017-03-06 16:47	> 1 w	0.1001705	0.0659682	0.0117785
EARTH	2021-01-04 04:02	< 1 s	0.0056234	0.0056155	0.0000026
EARTH	2025-01-01 15:39	> 1 d	0.0220638	0.0039740	0.0313666
EARTH	2028-12-24 02:02	> 1 d	0.1102648	0.0048511	0.0878569
MARS	2033-04-22 21:28	> 1 w	0.0346205	0.0204209	0.1256554

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
339.66829260	2.68982788	0.00391559	MINIMUM
21.97355873	89.88656459	0.02446483	MINIMUM
1.13458001	46.86128199	0.10798147	SADDLE
0.97807480	226.50734591	1.89437517	SADDLE
180.20850607	225.48186621	3.13172551	SADDLE
180.19376463	45.47089629	5.13308444	MAXIMUM

Download:

MOID Plots

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