Asteroids

2021PW4 help

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

Orbital Properties

Epoch

60800.0

MJD

Orbit type

Apollo

Perihelion (q)

1.009

Aphelion (Q)

2.275

Eccentricity (e)

0.386

Inclination (i)

1.2

deg

Orbit period (P)

768.5

Earth MOID

0.01943

U parameter

6.9

Next Earth close approach

Date

2061-06-26

Nominal distance (from Earth center)

0.0211

3156828

Maximum Brightness

19.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

24.8

mag

Diameter

29 - 60*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-08-07

Observatory

ATLAS-MLO, Mauna Loa

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

1.642027

1-sigma variation

0.000329

Unit

Eccentricity (e)

Value

0.385758

1-sigma variation

0.000125

Unit

Inclination (i)

Value

1.1977

1-sigma variation

0.0003

Unit

Long. of Ascending Node (Ω)

Value

188.3845

1-sigma variation

0.0011

Unit

Arg. of Perihelion (ω)

Value

99.8322

1-sigma variation

0.0005

Unit

Mean Anomaly (M)

Value

290.94023

1-sigma variation

0.19699

Unit

Perihelion distance

Value

1.008602

1-sigma variation

Unit

Aphelion distance

Value

2.275452

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.497745

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.310407

1-sigma variation

Unit

MOID

Value

0.019427

1-sigma variation

Unit

Orbit Period

Value

768.5443

1-sigma variation

Unit

U parameter

Value

6.9

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.08132E-7	4.10193E-8	1.11730E-7	-3.38283E-7	1.51433E-7	-6.47762E-5
e	4.10193E-8	1.55604E-8	4.23833E-8	-1.28304E-7	5.74150E-8	-2.45724E-5
i	1.11730E-7	4.23833E-8	1.15495E-7	-3.51193E-7	1.58404E-7	-6.69316E-5
Ω	-3.38283E-7	-1.28304E-7	-3.51193E-7	1.12529E-6	-5.48622E-7	2.02650E-4
ω	1.51433E-7	5.74150E-8	1.58404E-7	-5.48622E-7	2.98293E-7	-9.07191E-5
M	-6.47762E-5	-2.45724E-5	-6.69316E-5	2.02650E-4	-9.07191E-5	3.88039E-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

24.834

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

29 - 60*

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

1450

Unit

Source

[1]

Normalized RMS of residuals

Value

0.496438

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-08-07.460024

Unit

Source

[2]

Last Observation

Value

2021-09-10.37684

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

85 (1)

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 2021PW4 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	1956-06-09 21:02	> 1 w	0.0427873	0.0207367	0.0290922
EARTH	1977-06-01 15:00	> 1 d	0.0897872	0.0205722	0.0410252
EARTH	2000-08-23 08:03	> 1 d	0.1574758	0.0463942	0.0376048
EARTH	2021-08-04 15:10	< 1 min	0.0294722	0.0294475	0.0000082
EARTH	2061-06-26 15:05	> 1 w	0.0211021	0.0211004	0.0002268
EARTH	2082-08-11 05:31	> 1 mo	0.0487372	0.0179677	0.3883163
EARTH	2101-06-13 10:42	> 1 mo	0.0417007	0.0215793	0.7487008
EARTH	2122-07-23 01:02	> 1 mo	0.0194500	0.0184177	0.1094180

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
9.50945261	200.55434138	0.01942672	MINIMUM
351.01711044	172.40032328	0.02112066	MINIMUM
358.70167450	184.10038380	0.02219040	SADDLE
179.89347786	5.87078452	1.29208864	SADDLE
359.77684780	5.73919309	1.99222337	SADDLE
179.90074179	185.87422877	3.29152410	MAXIMUM

Download:

MOID Plots

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