Asteroids

2021HU help

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

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.875

Aphelion (Q)

2.284

Eccentricity (e)

0.446

Inclination (i)

6.9

deg

Orbit period (P)

725.2

Earth MOID

0.01898

U parameter

0.0

Next Earth close approach

Date

Nominal distance (from Earth center)

Maximum Brightness

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

25.1

mag

Diameter

25 - 60*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-04-17

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

1.579755

1-sigma variation

3.472E-9

Unit

Eccentricity (e)

Value

0.445873

1-sigma variation

1.374E-7

Unit

Inclination (i)

Value

6.9436

1-sigma variation

8.971E-6

Unit

Long. of Ascending Node (Ω)

Value

44.8223

1-sigma variation

3.241E-5

Unit

Arg. of Perihelion (ω)

Value

225.2471

1-sigma variation

3.768E-5

Unit

Mean Anomaly (M)

Value

86.69875

1-sigma variation

0.00001

Unit

Perihelion distance

Value

0.875385

1-sigma variation

Unit

Aphelion distance

Value

2.284125

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.853407

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.046809

1-sigma variation

Unit

MOID

Value

0.018983

1-sigma variation

Unit

Orbit Period

Value

725.2423

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.20534E-17	-1.59822E-16	5.12731E-15	-4.91485E-14	-8.12938E-17	2.15739E-15
e	-1.59822E-16	1.88777E-14	5.90206E-17	2.08246E-12	3.40008E-12	-1.22076E-12
i	5.12731E-15	5.90206E-17	8.04738E-11	-2.20972E-10	2.22262E-10	-3.30814E-12
Ω	-4.91485E-14	2.08246E-12	-2.20972E-10	1.05051E-9	-4.31572E-10	-1.23141E-10
ω	-8.12938E-17	3.40008E-12	2.22262E-10	-4.31572E-10	1.41983E-9	-2.35949E-10
M	2.15739E-15	-1.22076E-12	-3.30814E-12	-1.23141E-10	-2.35949E-10	8.97448E-11

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

25.139

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

25 - 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

1469

Unit

Source

[1]

Unobserved

Value

918

Unit

Source

[1]

Normalized RMS of residuals

Value

0.529934

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2019-04-07.308065

Unit

Source

[2]

Last Observation

Value

2023-04-15.475854

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

67 (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 2021HU 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	2007-08-29 06:14	< 1 min	0.1562899	0.1562880	0.0000006
EARTH	2009-08-20 22:35	< 1 min	0.1206933	0.1206928	0.0000002
EARTH	2011-08-07 03:29	< 1 min	0.1364363	0.1364354	0.0000003
EARTH	2013-07-14 09:53	< 1 min	0.1621729	0.1621721	0.0000003
EARTH	2015-06-23 02:39	< 1 min	0.1631000	0.1630994	0.0000002
EARTH	2017-05-31 21:17	< 1 min	0.1380413	0.1380409	0.0000001
EARTH	2019-05-12 15:37	< 1 min	0.0872674	0.0872671	0.0000001
EARTH	2021-04-29 10:51	< 1 s	0.0249484	0.0249482	0.0000001
EARTH	2023-04-23 10:16	< 1 s	0.0465213	0.0465211	0.0000001
EARTH	2025-04-16 16:50	< 1 s	0.1213542	0.1213539	0.0000001

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
325.46498376	113.70786129	0.01839664	MINIMUM
36.61392027	224.82760913	0.12030997	MINIMUM
6.21480404	177.61932153	0.16603840	SADDLE
180.80076371	348.20676075	1.30698532	SADDLE
0.85717294	348.80828899	1.85759978	SADDLE
179.91797922	167.66684219	3.29787512	MAXIMUM

Download:

MOID Plots

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