Asteroids

2021HY9 help

Last update: 2025-02-19 13:28 UTC

Orbital Properties

Epoch

60800.0

MJD

Orbit type

Apollo

Perihelion (q)

0.999

Aphelion (Q)

3.144

Eccentricity (e)

0.518

Inclination (i)

11.5

deg

Orbit period (P)

1088.7

Earth MOID

0.00767

U parameter

8.4

Next Earth close approach

Date

2027-04-06

Nominal distance (from Earth center)

0.12723

19032854

Maximum Brightness

mag

Risk

Object is in risk list

Object is not in priority list

Physical Properties

Absolute Magnitude (H)

mag

Diameter

7 - 15*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-04-20

Observatory

JPL SynTrack Robotic Telescope, Auberry

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

2.071166

1-sigma variation

0.005443

Unit

Eccentricity (e)

Value

0.517777

1-sigma variation

0.001058

Unit

Inclination (i)

Value

11.4754

1-sigma variation

0.0157

Unit

Long. of Ascending Node (Ω)

Value

31.6960

1-sigma variation

0.0120

Unit

Arg. of Perihelion (ω)

Value

197.0662

1-sigma variation

0.2491

Unit

Mean Anomaly (M)

Value

120.75080

1-sigma variation

0.32924

Unit

Perihelion distance

Value

0.998764

1-sigma variation

Unit

Aphelion distance

Value

3.143568

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

2.007228

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.008834

1-sigma variation

Unit

MOID

Value

0.007665

1-sigma variation

Unit

Orbit Period

Value

1088.7315

1-sigma variation

Unit

U parameter

Value

8.4

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	2.96216E-5	5.76092E-6	-8.53257E-5	6.53628E-5	-1.35598E-3	1.79191E-3
e	5.76092E-6	1.12040E-6	-1.65945E-5	1.27120E-5	-2.63715E-4	3.48497E-4
i	-8.53257E-5	-1.65945E-5	2.45784E-4	-1.88279E-4	3.90592E-3	-5.16163E-3
Ω	6.53628E-5	1.27120E-5	-1.88279E-4	1.44229E-4	-2.99208E-3	3.95401E-3
ω	-1.35598E-3	-2.63715E-4	3.90592E-3	-2.99208E-3	6.20719E-2	-8.20273E-2
M	1.79191E-3	3.48497E-4	-5.16163E-3	3.95401E-3	-8.20273E-2	1.08398E-1

Date of computation: 2025-02-19 13:28 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

27.991

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

7 - 15*

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

Unit

Source

[1]

Unobserved

Value

1483

Unit

Source

[1]

Normalized RMS of residuals

Value

1.03776

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-04-17.29148

Unit

Source

[2]

Last Observation

Value

2021-04-22.047611

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

17 (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 2021HY9 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	2015-04-03 11:33	> 1 d	0.1646517	0.0165096	0.0606983
EARTH	2018-04-13 04:14	> 1 d	0.0690185	0.0017244	0.0349521
EARTH	2021-04-22 10:26	< 1 min	0.0126231	0.0125841	0.0000130
EARTH	2024-04-19 18:55	> 1 d	0.0185420	0.0070216	0.0298492
EARTH	2027-04-06 17:45	> 1 d	0.1272268	0.0279686	0.0335439
EARTH	2119-05-04 18:51	> 1 mo	0.0568980	0.0226675	0.9296230
EARTH	2122-04-02 06:37	> 1 mo	0.1454511	0.0314532	0.9345320

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
351.02422212	109.97967942	0.00765751	MINIMUM
1.81850695	308.91141356	1.98712656	SADDLE
180.87881484	307.21252632	2.17130300	SADDLE
180.15015028	126.81579128	4.16662005	MAXIMUM

Download:

MOID Plots

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

Level lines of the squared distance function

2021HY9

Date in UTC	MJD	σ	σ_imp	Distance ± Width in RE	Stretching in RE/σ	IP	Exp. energy	PS	TS
2101-04-22.813	88545.813	-4.550	0.000	1.39 ± 0.005	7.76E3	2.28E-9	4.33E-11	-10.37	0


Based on 17 optical observations (of which 1 are rejected as outliers) from 2021/04/17.291 to 2021/04/22.048.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.48 and 1.48 Earth radii.
Coordinates for LOV = EQU scaled= 1 second= F.
AstOD software version= 4.0, Date of computation=20250305 085503.714 UTC.

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Download Impactor Table as: