Asteroids

2021GW4 help

Last update: 2025-07-29 02:36 UTC

Orbital Properties

Epoch

60800.0

MJD

Orbit type

Apollo

Perihelion (q)

0.976

Aphelion (Q)

1.829

Eccentricity (e)

0.304

Inclination (i)

5.1

deg

Orbit period (P)

606.7

Earth MOID

0.00047

U parameter

6.7

Next Earth close approach

Date

2026-03-29

Nominal distance (from Earth center)

0.09091

13599319

Maximum Brightness

26.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

29.4

mag

Diameter

4 - 8*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-04-08

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

60800.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.402584

1-sigma variation

0.000176

Unit

Eccentricity (e)

Value

0.303821

1-sigma variation

0.000093

Unit

Inclination (i)

Value

5.0718

1-sigma variation

0.0017

Unit

Long. of Ascending Node (Ω)

Value

22.5748

1-sigma variation

0.0002

Unit

Arg. of Perihelion (ω)

Value

206.9527

1-sigma variation

0.0008

Unit

Mean Anomaly (M)

Value

146.10187

1-sigma variation

0.16302

Unit

Perihelion distance

Value

0.976449

1-sigma variation

Unit

Aphelion distance

Value

1.828720

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.749114

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.000820

1-sigma variation

Unit

MOID

Value

0.000474

1-sigma variation

Unit

Orbit Period

Value

606.7251

1-sigma variation

Unit

U parameter

Value

6.7

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	3.10877E-8	1.64035E-8	-2.87982E-7	2.38426E-8	1.27652E-7	-2.87437E-5
e	1.64035E-8	8.65557E-9	-1.51964E-7	1.25810E-8	6.74864E-8	-1.51668E-5
i	-2.87982E-7	-1.51964E-7	2.77988E-6	-2.44410E-7	-1.18390E-6	2.66283E-4
Ω	2.38426E-8	1.25810E-8	-2.44410E-7	2.32882E-8	9.70860E-8	-2.20474E-5
ω	1.27652E-7	6.74864E-8	-1.18390E-6	9.70860E-8	6.18203E-7	-1.18072E-4
M	-2.87437E-5	-1.51668E-5	2.66283E-4	-2.20474E-5	-1.18072E-4	2.65764E-2

Date of computation: 2025-07-29 02:36 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

29.358

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

4 - 8*

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

1589

Unit

Source

[1]

Normalized RMS of residuals

Value

0.530376

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-04-08.230911

Unit

Source

[2]

Last Observation

Value

2021-04-12.033383

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

40 (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 2021GW4 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	1958-06-22 17:43	> 1 mo	0.0676759	0.0113718	13.6879407
EARTH	1973-04-10 02:52	> 1 w	0.0066261	0.0001050	0.0832046
EARTH	1984-06-24 17:21	> 1 mo	0.0718761	0.0118762	0.8203618
EARTH	2008-04-16 04:39	> 1 d	0.0097512	0.0001143	0.0068670
EARTH	2021-04-12 13:00	< 1 min	0.0001751	0.0001749	0.0000000
EARTH	2026-03-29 10:55	768.5	0.0909058	0.0738238	0.0056978
EARTH	2079-07-04 04:29	> 1 d	0.1670083	0.1141091	0.0193868
EARTH	2084-06-15 10:41	> 1 d	0.0837927	0.0750976	0.0073546
EARTH	2089-05-12 20:19	> 1 w	0.0576326	0.0413060	0.0068833
EARTH	2094-04-18 09:32	> 1 d	0.0178162	0.0003880	0.0101080
EARTH	2099-05-10 02:44	> 1 mo	0.0539606	0.0312910	0.0333347
EARTH	2104-06-12 03:48	> 1 mo	0.0779920	0.0720146	0.0455503
EARTH	2109-07-02 02:32	> 1 w	0.1483626	0.0823413	0.1979027

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
339.93986293	99.15758505	0.00047382	MINIMUM
181.92228282	309.00110864	0.84072473	SADDLE
2.58359828	310.00637529	1.96570622	SADDLE
181.06127127	128.38481914	2.83808311	MAXIMUM

Download:

MOID Plots

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