Asteroids

2021AD help

Last update: 2026-03-17 23:26 UTC

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.927

Aphelion (Q)

2.254

Eccentricity (e)

0.417

Inclination (i)

8.6

deg

Orbit period (P)

732.7

Earth MOID

0.01958

U parameter

8.4

Next Earth close approach

Date

2027-02-04

Nominal distance (from Earth center)

0.07995

11961076

Maximum Brightness

24.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

24.5

mag

Diameter

30 - 70*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-01-02

Observatory

University of Arizona Mt. Lemmon 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

61200.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.590561

1-sigma variation

0.002714

Unit

Eccentricity (e)

Value

0.416938

1-sigma variation

0.001396

Unit

Inclination (i)

Value

8.5685

1-sigma variation

0.0207

Unit

Long. of Ascending Node (Ω)

Value

296.4394

1-sigma variation

0.0134

Unit

Arg. of Perihelion (ω)

Value

206.1718

1-sigma variation

0.2341

Unit

Mean Anomaly (M)

Value

238.09239

1-sigma variation

3.84497

Unit

Perihelion distance

Value

0.927395

1-sigma variation

Unit

Aphelion distance

Value

2.253727

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

1.083438

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.027639

1-sigma variation

Unit

MOID

Value

0.019575

1-sigma variation

Unit

Orbit Period

Value

732.6960

1-sigma variation

Unit

U parameter

Value

8.4

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	7.36753E-6	3.78822E-6	5.63143E-5	-3.64161E-5	6.35322E-4	-1.04365E-2
e	3.78822E-6	1.94783E-6	2.89558E-5	-1.87240E-5	3.26670E-4	-5.36621E-3
i	5.63143E-5	2.89558E-5	4.30451E-4	-2.78334E-4	4.85620E-3	-7.97720E-2
Ω	-3.64161E-5	-1.87240E-5	-2.78334E-4	1.80032E-4	-3.14011E-3	5.15851E-2
ω	6.35322E-4	3.26670E-4	4.85620E-3	-3.14011E-3	5.47862E-2	-8.99966E-1
M	-1.04365E-2	-5.36621E-3	-7.97720E-2	5.15851E-2	-8.99966E-1	1.47838E1

Date of computation: 2026-03-17 23:26 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

24.499

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

30 - 70*

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

1969

Unit

Source

[1]

Normalized RMS of residuals

Value

0.756046

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-01-02.126937

Unit

Source

[2]

Last Observation

Value

2021-01-11.08698

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

28 (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 2021AD 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	2005-04-03 18:08	> 1 w	0.1838860	0.1394851	0.1404263
EARTH	2007-03-25 19:14	> 1 w	0.1487537	0.1312529	0.0872697
EARTH	2009-03-12 05:50	> 1 mo	0.1279555	0.1189485	0.0533698
EARTH	2011-02-26 23:01	> 1 mo	0.1130111	0.0992893	0.0544207
EARTH	2013-02-12 04:33	> 1 mo	0.0939224	0.0684583	0.0685554
EARTH	2015-02-01 07:42	> 1 mo	0.0727058	0.0422914	0.0777018
EARTH	2017-01-23 08:25	> 1 w	0.0515436	0.0275160	0.0709720
EARTH	2019-01-18 11:22	> 1 w	0.0350722	0.0218677	0.0394793
EARTH	2021-01-16 15:59	< 1 min	0.0320223	0.0315795	0.0001476
EARTH	2023-01-20 06:26	> 1 w	0.0407239	0.0231003	0.0409068
EARTH	2025-01-25 15:36	> 1 w	0.0576637	0.0304862	0.0688677
EARTH	2027-02-04 21:31	> 1 mo	0.0799549	0.0494586	0.0739052
EARTH	2029-02-16 19:05	> 1 mo	0.1003336	0.0784213	0.0651222
EARTH	2031-03-03 00:48	> 1 mo	0.1168032	0.1047491	0.0567740
EARTH	2033-03-16 23:50	> 1 mo	0.1335857	0.1224959	0.0682841
EARTH	2035-03-29 06:53	> 1 w	0.1603872	0.1328968	0.1218491

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
339.25072128	9.34142158	0.01959331	MINIMUM
181.56812816	222.33943420	1.24414315	SADDLE
2.24902068	223.77131974	1.93997230	SADDLE
180.28596615	41.50996138	3.24003705	MAXIMUM

Download:

MOID Plots

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