Asteroids

2021KN2 help

Last update: 2026-07-30 14:25 UTC

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.884

Aphelion (Q)

1.936

Eccentricity (e)

0.373

Inclination (i)

3.8

deg

Orbit period (P)

611.5

Earth MOID

0.00094

U parameter

6.9

Next Earth close approach

Date

2031-06-30

Nominal distance (from Earth center)

0.11227

16795670

Maximum Brightness

30.8

mag

Risk

Object is in risk list

Physical Properties

Absolute Magnitude (H)

28.5

mag

Diameter

5 - 12*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-05-30

Observatory

Tokyo-Kiso

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

1.409924

1-sigma variation

0.000232

Unit

Eccentricity (e)

Value

0.372949

1-sigma variation

0.000048

Unit

Inclination (i)

Value

3.7631

1-sigma variation

0.0003

Unit

Long. of Ascending Node (Ω)

Value

70.3177

1-sigma variation

0.0009

Unit

Arg. of Perihelion (ω)

Value

237.1596

1-sigma variation

0.0222

Unit

Mean Anomaly (M)

Value

337.34838

1-sigma variation

0.07734

Unit

Perihelion distance

Value

0.884094

1-sigma variation

Unit

Aphelion distance

Value

1.935755

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.534701

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.004018

1-sigma variation

Unit

MOID

Value

0.000944

1-sigma variation

Unit

Orbit Period

Value

611.4940

1-sigma variation

Unit

U parameter

Value

6.9

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	5.38572E-8	1.11338E-8	-7.93636E-8	-2.04550E-7	-5.16201E-6	1.79473E-5
e	1.11338E-8	2.30204E-9	-1.64222E-8	-4.22791E-8	-1.06702E-6	3.71015E-6
i	-7.93636E-8	-1.64222E-8	1.19146E-7	3.00647E-7	7.60302E-6	-2.64456E-5
Ω	-2.04550E-7	-4.22791E-8	3.00647E-7	7.77172E-7	1.96071E-5	-6.81645E-5
ω	-5.16201E-6	-1.06702E-6	7.60302E-6	1.96071E-5	4.94787E-4	-1.72019E-3
M	1.79473E-5	3.71015E-6	-2.64456E-5	-6.81645E-5	-1.72019E-3	5.98071E-3

Date of computation: 2026-07-30 14:25 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

28.485

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

5 - 12*

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

0.6

Unit

Source

[1]

Unobserved

Value

1892

Unit

Source

[1]

Normalized RMS of residuals

Value

0.863611

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-05-30.417796

Unit

Source

[2]

Last Observation

Value

2021-05-31.024816

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

66 (5)

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

Filters

Initial Date: *

Final Date: *

Normalised Only accepted

Max residual (arcsec):

* - these fields are required

Plot

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 2021KN2 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	1959-07-17 04:46	> 1 d	0.1371449	0.1278349	0.0031294
EARTH	1972-09-28 04:38	432.2	0.0495953	0.0472836	0.0008817
EARTH	1977-05-17 00:09	48.5	0.1827657	0.1809037	0.0006207
EARTH	1990-06-11 07:38	> 1 d	0.0665239	0.0459564	0.0068609
EARTH	2003-09-03 23:24	> 1 d	0.1172859	0.1081637	0.0030683
MARS	2015-06-02 18:35	62.8	0.0204657	0.0170316	0.0012963
EARTH	2016-10-12 13:14	146.0	0.1547957	0.1493260	0.0018262
EARTH	2021-05-31 02:12	< 1 s	0.0009660	0.0009658	0.0000001
EARTH	2026-06-02 22:35	343.9	0.0205055	0.0155006	0.0016691
EARTH	2031-06-30 04:52	> 1 d	0.1122721	0.1043041	0.0026617
EARTH	2036-08-03 05:27	> 1 d	0.1404173	0.1391559	0.0004688
EARTH	2041-09-09 17:20	> 1 d	0.1013127	0.0749066	0.0100423
EARTH	2046-09-29 23:47	> 1 d	0.0650363	0.0603674	0.0084894
EARTH	2051-10-10 11:35	> 1 d	0.1768647	0.0838829	0.0337398
EARTH	2093-05-24 01:03	> 1 d	0.0822781	0.0011343	0.0852816
EARTH	2098-06-04 20:51	> 1 w	0.0294063	0.0001484	0.0452928
EARTH	2103-07-21 06:03	> 1 mo	0.1361968	0.0914919	0.0192839
EARTH	2108-09-11 03:37	> 1 mo	0.1010317	0.0613306	0.1522820
EARTH	2113-10-05 21:23	> 1 w	0.1011608	0.0597215	0.3318417
MARS	2120-09-17 12:12	> 1 d	0.0482510	0.0160436	0.3907227

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
318.92428982	144.51964681	0.00094358	MINIMUM
39.99836070	260.66612296	0.06049644	MINIMUM
0.96423054	204.90392603	0.14147720	SADDLE
179.82495743	22.70725808	0.95400196	SADDLE
359.15124770	22.15841335	1.86815996	SADDLE
179.42715372	202.43454165	2.95027730	MAXIMUM

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MOID Plots

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

Level lines of the squared distance function

2021KN2

Date in UTC	MJD	σ	σ_imp	Distance ± Width in RE	Stretching in RE	IP	Impact energy	PS	TS
2083-05-31.945	82010.945	-4.336	0.000	1.22 ± 0.000	1.78E4	3.54E-9	8.64E-3	-10.34	0
2110-06-01.862	91872.862	-0.807	0.000	0.29 ± 0.000	1.97E8	4.43E-9	8.89E-3	-10.40	0


Based on 66 optical observations (of which 5 are rejected as outliers) from 2021/05/30.418 to 2021/05/31.025.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.51 and 1.51 Earth radii.
Coordinates for LOV = EQU scaled= 1 second= F.
AstOD software version= 4.0, Date of computation=20250805 130500.123 UTC.

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Download Impactor Table as: