Asteroids

2021AB1 help

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

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Aten

Perihelion (q)

0.393

Aphelion (Q)

1.071

Eccentricity (e)

0.463

Inclination (i)

9.1

deg

Orbit period (P)

228.6

Earth MOID

0.01100

U parameter

8.2

Next Earth close approach

Date

2030-12-27

Nominal distance (from Earth center)

0.09155

13695180

Maximum Brightness

25.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

26.7

mag

Diameter

12 - 27*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-01-04

Observatory

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

61000.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

0.731725

1-sigma variation

0.000277

Unit

Eccentricity (e)

Value

0.462983

1-sigma variation

0.000900

Unit

Inclination (i)

Value

9.0600

1-sigma variation

0.0283

Unit

Long. of Ascending Node (Ω)

Value

101.3626

1-sigma variation

0.0007

Unit

Arg. of Perihelion (ω)

Value

201.6841

1-sigma variation

0.0072

Unit

Mean Anomaly (M)

Value

58.55714

1-sigma variation

1.53681

Unit

Perihelion distance

Value

0.392949

1-sigma variation

Unit

Aphelion distance

Value

1.070502

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.025303

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.616196

1-sigma variation

Unit

MOID

Value

0.011004

1-sigma variation

Unit

Orbit Period

Value

228.6233

1-sigma variation

Unit

U parameter

Value

8.2

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	7.68868E-8	-2.49373E-7	-7.84777E-6	1.64780E-7	1.81375E-6	-4.26128E-4
e	-2.49373E-7	8.09337E-7	2.54503E-5	-5.27096E-7	-5.81319E-6	1.38189E-3
i	-7.84777E-6	2.54503E-5	8.01122E-4	-1.68667E-5	-1.85587E-4	4.34958E-2
Ω	1.64780E-7	-5.27096E-7	-1.68667E-5	4.60896E-7	4.87074E-6	-9.16189E-4
ω	1.81375E-6	-5.81319E-6	-1.85587E-4	4.87074E-6	5.20229E-5	-1.00798E-2
M	-4.26128E-4	1.38189E-3	4.34958E-2	-9.16189E-4	-1.00798E-2	2.36180E0

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

26.71

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

12 - 27*

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

1852

Unit

Source

[1]

Normalized RMS of residuals

Value

0.526269

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-01-04.169894

Unit

Source

[2]

Last Observation

Value

2021-01-06.166923

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

21 (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 2021AB1 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	1954-02-08 22:20	> 1 d	0.1079545	0.1078692	0.0008646
EARTH	1959-01-29 23:44	> 1 d	0.1096080	0.1095740	0.0001444
EARTH	1964-01-18 08:26	> 1 d	0.0994348	0.0970666	0.0008621
EARTH	1969-01-06 23:01	> 1 d	0.0697464	0.0532328	0.0055712
EARTH	1973-12-30 18:43	> 1 d	0.0229608	0.0123230	0.0160031
EARTH	1978-12-28 15:27	1272.6	0.0224209	0.0125344	0.0195389
EARTH	1983-12-27 21:22	89.2	0.0919792	0.0526993	0.0132645
EARTH	1988-12-28 08:13	8.6	0.1707831	0.1694838	0.0004333
EARTH	1991-02-17 10:56	176.8	0.1631386	0.1461173	0.0061668
EARTH	1996-02-16 07:34	1118.5	0.1204227	0.1125991	0.0073680
MERCURY	1998-11-07 00:49	> 1 d	0.0390597	0.0003968	0.0358462
EARTH	2001-02-09 10:44	> 1 d	0.1090353	0.1089226	0.0009670
MERCURY	2001-12-27 06:51	> 1 d	0.0187559	0.0041427	0.0546365
MERCURY	2005-02-14 19:35	> 1 d	0.0087929	0.0049296	0.0593163
EARTH	2006-01-29 20:09	> 1 d	0.1106826	0.1105663	0.0006290
MERCURY	2008-04-05 01:39	> 1 d	0.0414055	0.0040212	0.0654019
EARTH	2011-01-17 08:00	> 1 d	0.0985004	0.0776077	0.0082128
EARTH	2016-01-06 11:47	> 1 d	0.0641752	0.0375748	0.0092908
EARTH	2020-12-30 02:58	1.4	0.0171955	0.0170773	0.0000394
EARTH	2025-12-28 10:49	748.4	0.0246071	0.0114446	0.0127090
EARTH	2030-12-27 19:35	84.4	0.0915466	0.0337377	0.0197295
EARTH	2035-12-29 06:40	646.6	0.1708046	0.1047986	0.0220799
EARTH	2038-02-17 09:47	5.7	0.1625506	0.1253050	0.0148271
EARTH	2043-02-15 22:37	1346.4	0.1196404	0.1103578	0.0071355
EARTH	2048-02-09 23:57	> 1 d	0.1103732	0.1102636	0.0005473
EARTH	2053-01-29 17:55	> 1 d	0.1114793	0.1103966	0.0013516
EARTH	2058-01-19 00:51	> 1 d	0.1021273	0.0859005	0.0061590
MERCURY	2060-04-05 02:07	> 1 d	0.0496109	0.0061044	0.0215745
EARTH	2063-01-08 22:22	> 1 d	0.0754402	0.0421282	0.0118286
MERCURY	2063-05-25 23:34	> 1 d	0.0377316	0.0004111	0.0263674
MERCURY	2066-07-14 08:02	> 1 d	0.0249326	0.0032610	0.0273202
EARTH	2068-01-01 18:55	> 1 d	0.0331467	0.0111860	0.0134465
MERCURY	2069-08-30 23:28	> 1 d	0.0248413	0.0031630	0.0186009
MERCURY	2072-10-17 05:26	1170.6	0.0277256	0.0080895	0.0066918
EARTH	2072-12-28 21:41	353.5	0.0128475	0.0100316	0.0031920
MERCURY	2075-12-07 21:04	163.7	0.0112114	0.0075069	0.0014665
EARTH	2077-12-27 17:27	53.1	0.0941918	0.0830465	0.0037178
EARTH	2082-12-29 16:27	474.1	0.1911225	0.1523639	0.0129279
EARTH	2085-02-17 06:20	165.3	0.1476174	0.1267212	0.0092533
EARTH	2090-02-13 17:38	> 1 d	0.1139044	0.1132572	0.0020963
EARTH	2095-02-03 06:42	> 1 d	0.1128688	0.1124369	0.0014154
EARTH	2100-01-19 21:51	> 1 w	0.1035218	0.0821747	0.0096964
EARTH	2105-01-07 02:21	> 1 d	0.0654907	0.0192304	0.0286331
MERCURY	2106-01-12 23:22	> 1 w	0.0265474	0.0020119	0.0695961
MERCURY	2109-03-04 09:35	> 1 d	0.0072839	0.0037552	0.0686627
EARTH	2109-12-30 16:35	> 1 d	0.0090997	0.0090779	0.0014491
MERCURY	2112-04-22 18:40	> 1 w	0.0442590	0.0019577	0.3342737
EARTH	2114-12-29 01:31	1156.4	0.0846403	0.0118806	0.3107461
EARTH	2119-12-30 20:33	> 1 w	0.1833989	0.0156039	0.5476834
EARTH	2122-02-18 16:27	> 1 d	0.1543289	0.1191877	0.3766117

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
139.18413284	356.44343868	0.01100425	MINIMUM
208.66349901	38.38977706	0.10894065	MINIMUM
194.75636310	29.93317342	0.11021820	SADDLE
359.67556295	201.92123355	0.62503071	SADDLE
358.96224744	20.67406274	1.37719194	SADDLE
178.92863460	200.51899947	2.08664048	MAXIMUM

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MOID Plots

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