Asteroids

2021OA1 help

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

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Amor

Perihelion (q)

1.048

Aphelion (Q)

2.361

Eccentricity (e)

0.385

Inclination (i)

6.6

deg

Orbit period (P)

812.6

Earth MOID

0.04114

U parameter

7.6

Next Earth close approach

Date

2041-09-06

Nominal distance (from Earth center)

0.11488

17185835

Maximum Brightness

21.9

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

24.3

mag

Diameter

40 - 80*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-07-29

Observatory

ATLAS-MLO, Mauna Loa

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

1.704235

1-sigma variation

0.001040

Unit

Eccentricity (e)

Value

0.385242

1-sigma variation

0.000358

Unit

Inclination (i)

Value

6.6309

1-sigma variation

0.0045

Unit

Long. of Ascending Node (Ω)

Value

131.3901

1-sigma variation

0.0012

Unit

Arg. of Perihelion (ω)

Value

197.9650

1-sigma variation

0.0024

Unit

Mean Anomaly (M)

Value

328.62643

1-sigma variation

0.62630

Unit

Perihelion distance

Value

1.047693

1-sigma variation

Unit

Aphelion distance

Value

2.360778

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

1.304858

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.046364

1-sigma variation

Unit

MOID

Value

0.041142

1-sigma variation

Unit

Orbit Period

Value

812.6299

1-sigma variation

Unit

U parameter

Value

7.6

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.08238E-6	3.72436E-7	4.63856E-6	1.21171E-6	-2.52343E-6	-6.51592E-4
e	3.72436E-7	1.28151E-7	1.59607E-6	4.16936E-7	-8.68263E-7	-2.24205E-4
i	4.63856E-6	1.59607E-6	1.98787E-5	5.19287E-6	-1.08128E-5	-2.79240E-3
Ω	1.21171E-6	4.16936E-7	5.19287E-6	1.35674E-6	-2.82271E-6	-7.29446E-4
ω	-2.52343E-6	-8.68263E-7	-1.08128E-5	-2.82271E-6	5.91679E-6	1.51908E-3
M	-6.51592E-4	-2.24205E-4	-2.79240E-3	-7.29446E-4	1.51908E-3	3.92257E-1

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

24.253

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

40 - 80*

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

1546

Unit

Source

[1]

Normalized RMS of residuals

Value

0.551918

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-07-28.484087

Unit

Source

[2]

Last Observation

Value

2021-08-12.41235

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

76 (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 2021OA1 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
EARTH	1972-07-24 17:33	> 1 w	0.1078552	0.0182377	0.1102892
EARTH	1992-09-10 00:08	> 1 w	0.1364528	0.0335666	0.1301715
EARTH	2021-08-05 20:30	< 1 min	0.0488446	0.0487309	0.0000379
EARTH	2041-09-06 13:12	> 1 w	0.1148802	0.0233339	0.0913379
EARTH	2070-07-20 10:51	> 1 w	0.1584190	0.0085518	0.1013726
EARTH	2090-08-20 21:41	> 1 d	0.0554046	0.0317539	0.0106503
7 Iris	2095-09-24 14:53	633.0	0.0080115	0.0079910	0.0002560
EARTH	2119-07-28 19:57	> 1 w	0.1010815	0.0228859	0.0556287

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
352.84597092	216.90068461	0.04244821	MINIMUM
179.70700002	46.53801673	1.37295991	SADDLE
358.72984230	45.75374951	2.03594108	SADDLE
179.15420575	226.16706878	3.37130011	MAXIMUM

Download:

MOID Plots

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