Asteroids

2021HD help

Last update: 2024-04-19 00:31 UTC

Orbital Properties

Epoch

60400.0

MJD

Orbit type

Aten

Perihelion (q)

0.615

Aphelion (Q)

1.213

Eccentricity (e)

0.327

Inclination (i)

14.1

deg

Orbit period (P)

319.0

Earth MOID

0.00892

U parameter

6.2

Next Earth close approach

Date

2028-04-19

Nominal distance (from Earth center)

0.04661

6972804

Maximum Brightness

mag

Risk

Object is not in risk list

Object is not in priority list

Physical Properties

Absolute Magnitude (H)

26.2

mag

Diameter

15 - 30*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-04-16

Observatory

Pan-STARRS 1, Haleakala

Orbit Visualiser

Click the button to start Orbit Visualiser

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

60400.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

0.913771

1-sigma variation

0.000028

Unit

Eccentricity (e)

Value

0.327412

1-sigma variation

0.000211

Unit

Inclination (i)

Value

14.0787

1-sigma variation

0.0116

Unit

Long. of Ascending Node (Ω)

Value

208.3687

1-sigma variation

0.0009

Unit

Arg. of Perihelion (ω)

Value

127.6493

1-sigma variation

0.0046

Unit

Mean Anomaly (M)

Value

41.17896

1-sigma variation

0.02577

Unit

Perihelion distance

Value

0.614591

1-sigma variation

Unit

Aphelion distance

Value

1.212950

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.015472

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.314686

1-sigma variation

Unit

MOID

Value

0.008924

1-sigma variation

Unit

Orbit Period

Value

319.0467

1-sigma variation

Unit

U parameter

Value

6.2

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	7.84074E-10	5.72895E-9	3.16993E-7	-2.38778E-8	-1.27997E-7	-7.03688E-7
e	5.72895E-9	4.43221E-8	2.45108E-6	-1.85089E-7	-9.24170E-7	-4.85839E-6
i	3.16993E-7	2.45108E-6	1.35552E-4	-1.02359E-5	-5.11414E-5	-2.68979E-4
Ω	-2.38778E-8	-1.85089E-7	-1.02359E-5	7.73036E-7	3.85017E-6	2.02083E-5
ω	-1.27997E-7	-9.24170E-7	-5.11414E-5	3.85017E-6	2.09448E-5	1.16145E-4
M	-7.03688E-7	-4.85839E-6	-2.68979E-4	2.02083E-5	1.16145E-4	6.64111E-4

Date of computation: 2024-02-21 14:29 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

26.194

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

15 - 30*

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 ODIM	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

1095

Unit

Source

[1]

Normalized RMS of residuals

Value

0.593344

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-04-16.319238

Unit

Source

[2]

Last Observation

Value

2021-04-20.141607

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

[3]

Last Observation

Value

Unit

Source

[3]

Delay (Discarded)

Value

0 (0)

Unit

Source

[1]

Doppler (Discarded)

Value

0 (0)

Unit

Source

[1]

Total Radar Observations (Discarded)

Value

0 (0)

Unit

Source

[1]

Note: The ASCII file is in a format suitable for Orbfit input.

Sources

No.	Name	Additional
[1]	ESA ODIM	ESA orbit determination and impact monitoring system
[2]	MPC	Minor Planet Center: https://www.minorplanetcenter.net
[3]	JPL Radar Observations	Jet Propulsion Laboratory: https://ssd.jpl.nasa.gov/dat/radar_data_ast.txt

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 2021HD from 1950 to 2124

Body	Date in UTC	Time uncert. in min	Nominal distance in au	Min. possibile distance in au	Distance uncert. in au
EARTH	1960-04-18 22:44	20.9	0.0821654	0.0808141	0.0004506
EARTH	1967-04-18 20:15	21.7	0.0822724	0.0795534	0.0009064
EARTH	1987-04-17 15:57	122.7	0.1240712	0.1201687	0.0013016
EARTH	1994-04-19 16:20	18.4	0.0375846	0.0337715	0.0012732
VENUS	2005-12-01 12:42	190.9	0.0409634	0.0341452	0.0023250
EARTH	2014-04-14 19:27	220.1	0.1525936	0.1488320	0.0012544
VENUS	2016-05-16 23:48	192.6	0.0345218	0.0281423	0.0022070
EARTH	2021-04-20 07:42	< 1 min	0.0269761	0.0269164	0.0000199
EARTH	2028-04-19 08:03	48.4	0.0466103	0.0410199	0.0018691
EARTH	2035-04-17 05:06	88.0	0.1549646	0.1482864	0.0022263
VENUS	2053-11-22 14:38	111.9	0.0229990	0.0211815	0.0006488
EARTH	2055-04-10 22:23	229.6	0.1818425	0.1783774	0.0011557
EARTH	2062-04-20 11:25	4.8	0.0262844	0.0234177	0.0009632
VENUS	2064-05-08 21:23	18.5	0.0171445	0.0161567	0.0003325
EARTH	2069-04-17 13:52	47.4	0.1172603	0.1140806	0.0010600
VENUS	2074-10-24 09:05	330.9	0.0144956	0.0143109	0.0003596
VENUS	2085-04-09 07:39	> 1 d	0.0144802	0.0143548	0.0009549
EARTH	2089-04-14 10:54	> 1 w	0.1516272	0.0229961	0.2046429
VENUS	2095-09-26 06:31	> 1 mo	0.0383193	0.0150945	0.6062790
EARTH	2096-04-19 22:06	> 1 d	0.0213968	0.0087895	0.4599140
EARTH	2103-04-21 05:10	> 1 w	0.0283365	0.0088580	0.7193612
EARTH	2110-04-18 10:33	> 1 w	0.1345200	0.0099448	0.6496694
VENUS	2122-10-17 10:14	> 1 w	0.0395652	0.0191884	0.1270458

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