Asteroids

2008HJ help

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

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.968

Aphelion (Q)

2.296

Eccentricity (e)

0.407

Inclination (i)

0.9

deg

Orbit period (P)

761.5

Earth MOID

0.00186

U parameter

7.1

Next Earth close approach

Date

2033-06-08

Nominal distance (from Earth center)

0.04609

6895091

Maximum Brightness

34.4

mag

Risk

Object is in risk list

Physical Properties

Absolute Magnitude (H)

25.8

mag

Diameter

18 - 40*

Taxonomic type

Rotation period (T)

0.01185

Discovery Information

Discovery Date

2008-04-24

Observatory

Lincoln Laboratory ETS, New Mexico

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

1.631949

1-sigma variation

0.000291

Unit

Eccentricity (e)

Value

0.407112

1-sigma variation

0.000115

Unit

Inclination (i)

Value

0.9236

1-sigma variation

0.0001

Unit

Long. of Ascending Node (Ω)

Value

47.4543

1-sigma variation

0.0011

Unit

Arg. of Perihelion (ω)

Value

204.2088

1-sigma variation

0.0009

Unit

Mean Anomaly (M)

Value

139.37917

1-sigma variation

0.80805

Unit

Perihelion distance

Value

0.967562

1-sigma variation

Unit

Aphelion distance

Value

2.296335

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

1.173444

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.017658

1-sigma variation

Unit

MOID

Value

0.001858

1-sigma variation

Unit

Orbit Period

Value

761.4795

1-sigma variation

Unit

U parameter

Value

7.1

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	8.44332E-8	3.33184E-8	4.19898E-8	3.21161E-7	-2.50418E-7	-2.34799E-4
e	3.33184E-8	1.31479E-8	1.65704E-8	1.26727E-7	-9.87993E-8	-9.26545E-5
i	4.19898E-8	1.65704E-8	2.10058E-8	1.58488E-7	-1.22896E-7	-1.16769E-4
Ω	3.21161E-7	1.26727E-7	1.58488E-7	1.23419E-6	-9.69135E-7	-8.93110E-4
ω	-2.50418E-7	-9.87993E-8	-1.22896E-7	-9.69135E-7	7.69794E-7	6.96379E-4
M	-2.34799E-4	-9.26545E-5	-1.16769E-4	-8.93110E-4	6.96379E-4	6.52948E-1

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

0.01185

Unit

Source

[1]

Quality

Value

Unit

Source

[-]

Amplitude

Value

0.8

Unit

mag

Source

[1]

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

25.809

Unit

mag

Source

[2]

Slope Parameter (G)

Value

0.15**

Unit

mag

Source

[2]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[3]

Diameter

Value

18 - 40*

Unit

Source

[3]

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]	EARN	1.) Miles, R. (2008) CBET HREF="http://www.cbat.eps.harvard.edu/iau/cbet/001300/CBET001382.txt"> 1382. (2008 HJ) (rapid rotator 42.67 secs) 2.) Miles, R. et al. (2008) TheAstronomer, 45, 531. (Photometry of small near-Earth asteroids) (2008HJ,2008JL24,2008JP24)
[2]	ESA Aegis	ESA orbit determination and impact monitoring system
[3]	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

6368

Unit

Source

[1]

Normalized RMS of residuals

Value

0.485943

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2008-04-24.24725

Unit

Source

[2]

Last Observation

Value

2008-04-30.376536

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

97 (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 2008HJ 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	1953-07-08 03:34	> 1 d	0.0178099	0.0128579	0.0094785
EARTH	1972-07-25 23:12	1189.4	0.1625860	0.1250231	0.0125359
EARTH	1989-04-16 14:34	> 1 d	0.0952429	0.0062725	0.0298877
EARTH	2008-04-29 19:23	< 1 s	0.0071655	0.0071605	0.0000017
EARTH	2033-06-08 05:07	> 1 w	0.0460908	0.0375257	0.0034496
EARTH	2058-07-08 05:59	> 1 d	0.0142629	0.0137864	0.0049553
EARTH	2081-06-18 03:37	> 1 mo	0.0406314	0.0174690	0.3294891
EARTH	2104-04-28 16:09	> 1 mo	0.0209244	0.0000941	0.9972832
MARS	2110-11-27 20:13	> 1 mo	0.0265530	0.0226795	3.3103649

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
339.99530988	118.20457910	0.00172018	MINIMUM
21.92017127	182.69703380	0.01390753	MINIMUM
1.35872322	151.04830309	0.04719197	SADDLE
180.46109540	329.93077415	1.31067176	SADDLE
1.05696566	330.59018651	1.95321848	SADDLE
180.46047112	149.93610841	3.31050026	MAXIMUM

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MOID Plots

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

Level lines of the squared distance function

2008HJ

Date in UTC	MJD	σ	Distance ± Width in RE	Stretching in RE	IP	Impact energy	PS
2077-05-02.709	79790.709	2.433	0.87 ± 0.000	8.57E4	7.63E-7	4.42E-1	-6.60
2081-05-02.503	81251.503	0.087	0.28 ± 0.000	1.87E4	7.52E-5	4.40E-1	-4.64
2096-05-01.961	86729.961	0.084	0.96 ± 0.000	1.43E7	8.35E-8	4.42E-1	-7.69
2102-05-03.693	88921.693	4.592	0.56 ± 0.000	9.42E3	3.92E-9	4.44E-1	-9.05
2102-05-03.702	88921.702	0.074	0.77 ± 0.000	1.42E6	9.39E-7	4.42E-1	-6.68
2102-05-04.156	88922.156	-0.175	0.93 ± 0.000	2.85E4	4.21E-5	4.42E-1	-5.02
2102-05-04.170	88922.170	-1.332	0.88 ± 0.000	1.84E5	2.94E-6	4.42E-1	-6.18
2104-05-03.358	89652.358	2.162	1.65 ± 0.000	1.97E5	4.56E-7	4.41E-1	-7.00
2104-05-03.369	89652.369	-1.384	1.21 ± 0.000	1.46E5	2.78E-6	4.39E-1	-6.22
2104-05-03.406	89652.406	0.010	1.34 ± 0.000	1.02E4	9.35E-5	4.41E-1	-4.69
2104-05-03.639	89652.639	-0.177	0.19 ± 0.000	2.10E7	6.67E-8	4.41E-1	-7.84
2106-05-03.758	90382.758	0.005	1.07 ± 0.000	1.79E6	6.69E-7	4.39E-1	-6.86
2106-05-03.854	90382.854	0.152	0.59 ± 0.000	3.66E4	3.66E-5	4.40E-1	-5.12
2108-05-03.065	91113.065	0.150	0.42 ± 0.000	5.81E6	2.36E-7	4.41E-1	-7.32
2108-05-03.168	91113.168	0.105	1.77 ± 0.000	8.60E5	1.86E-7	4.41E-1	-7.42
2110-05-03.981	91843.981	0.098	1.74 ± 0.000	1.89E6	2.34E-7	4.40E-1	-7.33
2112-05-03.345	92574.345	0.095	1.71 ± 0.000	3.57E6	1.18E-7	4.42E-1	-7.64
2113-05-03.556	92939.556	2.236	1.68 ± 0.004	1.40E7	6.73E-9	4.43E-1	-8.89
2113-05-03.609	92939.609	0.083	1.31 ± 0.011	1.61E7	6.03E-8	4.41E-1	-7.94
2114-05-03.851	93304.851	2.349	1.27 ± 0.002	5.48E6	1.65E-8	4.41E-1	-8.50
2119-05-03.784	95130.784	0.017	0.23 ± 0.022	1.43E7	9.87E-8	4.43E-1	-7.75
2120-05-03.536	95496.536	-3.377	1.36 ± 0.000	5.44E6	8.00E-10	4.40E-1	-9.85
2121-05-03.770	95861.770	-2.331	0.58 ± 0.003	9.85E6	9.09E-9	4.40E-1	-8.79


Based on 97 optical observations (of which 1 are rejected as outliers) from 2008/04/24.247 to 2008/04/30.377.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.79 and 1.79 Earth radii.
Coordinates for LOV = EQU scaled= 1 second= F.
Aegis software version= 4.0, Date of computation=20250805 130500.123 UTC.

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