Asteroids

2021WC1 help

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

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.812

Aphelion (Q)

1.940

Eccentricity (e)

0.410

Inclination (i)

9.0

deg

Orbit period (P)

589.6

Earth MOID

0.00129

U parameter

7.3

Next Earth close approach

Date

2042-11-21

Nominal distance (from Earth center)

0.10917

16331599

Maximum Brightness

26.5

mag

Risk

Object is in risk list

Physical Properties

Absolute Magnitude (H)

28.4

mag

Diameter

6 - 12*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-11-27

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

1.376040

1-sigma variation

0.000413

Unit

Eccentricity (e)

Value

0.409955

1-sigma variation

0.000226

Unit

Inclination (i)

Value

9.0151

1-sigma variation

0.0041

Unit

Long. of Ascending Node (Ω)

Value

246.6933

1-sigma variation

0.0003

Unit

Arg. of Perihelion (ω)

Value

246.4628

1-sigma variation

0.0005

Unit

Mean Anomaly (M)

Value

138.24224

1-sigma variation

0.38280

Unit

Perihelion distance

Value

0.811925

1-sigma variation

Unit

Aphelion distance

Value

1.940155

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.354089

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.002889

1-sigma variation

Unit

MOID

Value

0.001291

1-sigma variation

Unit

Orbit Period

Value

589.5831

1-sigma variation

Unit

U parameter

Value

7.3

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.70295E-7	9.32402E-8	1.67679E-6	-2.28557E-8	-1.01278E-7	-1.57970E-4
e	9.32402E-8	5.10557E-8	9.17085E-7	-1.20397E-8	-5.46307E-8	-8.64921E-5
i	1.67679E-6	9.17085E-7	1.68003E-5	-3.58680E-7	-1.14679E-6	-1.55534E-3
Ω	-2.28557E-8	-1.20397E-8	-3.58680E-7	6.52550E-8	8.63576E-8	2.11612E-5
ω	-1.01278E-7	-5.46307E-8	-1.14679E-6	8.63576E-8	2.07062E-7	9.38862E-5
M	-1.57970E-4	-8.64921E-5	-1.55534E-3	2.11612E-5	9.38862E-5	1.46536E-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

28.415

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

6 - 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

0.7

Unit

Source

[1]

Unobserved

Value

1428

Unit

Source

[1]

Normalized RMS of residuals

Value

0.543376

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-11-27.184031

Unit

Source

[2]

Last Observation

Value

2021-11-27.84946

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

22 (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 2021WC1 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	1954-03-19 20:12	> 1 mo	0.1867750	0.0878636	0.1637606
EARTH	1966-12-09 01:07	> 1 mo	0.0911666	0.0097616	0.2726086
EARTH	1975-04-18 22:16	> 1 w	0.0978407	0.0977960	0.0040207
EARTH	2000-11-24 16:56	> 1 d	0.0476717	0.0024496	0.0541405
EARTH	2021-11-28 15:02	< 1 min	0.0013631	0.0013615	0.0000005
EARTH	2042-11-21 11:03	> 1 d	0.1091700	0.0038092	0.0545279
EARTH	2059-04-24 08:54	> 1 d	0.1360648	0.1026445	0.0284585
EARTH	2071-12-28 07:55	> 1 d	0.1604522	0.1130885	0.0161395
EARTH	2080-04-17 13:09	583.9	0.1047605	0.1027316	0.0010777
EARTH	2092-12-11 12:31	> 1 d	0.1048257	0.0520872	0.0176811
EARTH	2101-04-16 13:45	> 1 d	0.1144425	0.1021347	0.0136000
EARTH	2113-12-14 22:27	> 1 w	0.1147342	0.0140212	0.0465748
EARTH	2122-04-19 11:48	> 1 d	0.1032993	0.1020768	0.0079569

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
313.73134195	324.58215025	0.00136519	MINIMUM
52.71861029	105.28397101	0.10429292	MINIMUM
6.35656000	39.82257456	0.21989644	SADDLE
181.77057082	212.06651883	0.94810012	SADDLE
2.01480812	213.14488020	1.82093580	SADDLE
180.15735493	30.99897220	2.91917519	MAXIMUM

Download:

MOID Plots

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

Level lines of the squared distance function

2021WC1

Date in UTC	MJD	σ	Distance ± Width in RE	Stretching in RE	IP	Impact energy	PS
2063-11-29.405	74887.405	-4.556	1.23 ± 0.008	1.79E5	9.20E-11	1.25E-2	-11.63
2069-11-28.884	77078.884	-4.677	0.06 ± 0.012	4.89E5	4.04E-11	1.25E-2	-12.05
2073-11-28.879	78539.879	1.855	1.33 ± 0.000	1.62E8	3.64E-10	1.26E-2	-11.13
2077-11-28.919	80000.919	1.907	0.57 ± 0.008	7.91E5	2.08E-7	1.26E-2	-8.41
2079-11-29.407	80731.407	1.480	0.06 ± 0.000	2.31E7	1.61E-8	1.26E-2	-9.53
2079-11-29.426	80731.426	-2.512	1.23 ± 0.007	1.05E5	2.15E-7	1.26E-2	-8.41


Based on 22 optical observations (of which 0 are rejected as outliers) from 2021/11/27.184 to 2021/11/27.849.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.39 and 1.39 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: