Asteroids

2021BJ help

Last update: 2026-07-30 14:25 UTC

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.943

Aphelion (Q)

2.221

Eccentricity (e)

0.404

Inclination (i)

1.6

deg

Orbit period (P)

726.7

Earth MOID

0.01879

U parameter

7.0

Next Earth close approach

Date

2026-11-11

Nominal distance (from Earth center)

0.02873

4298336

Maximum Brightness

21.6

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

25.4

mag

Diameter

22 - 50*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-01-16

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

61200.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.581934

1-sigma variation

0.000316

Unit

Eccentricity (e)

Value

0.403960

1-sigma variation

0.000161

Unit

Inclination (i)

Value

1.5720

1-sigma variation

0.0049

Unit

Long. of Ascending Node (Ω)

Value

334.4938

1-sigma variation

0.0222

Unit

Arg. of Perihelion (ω)

Value

104.4919

1-sigma variation

0.0166

Unit

Mean Anomaly (M)

Value

270.66042

1-sigma variation

0.51054

Unit

Perihelion distance

Value

0.942896

1-sigma variation

Unit

Aphelion distance

Value

2.220971

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.462229

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.212755

1-sigma variation

Unit

MOID

Value

0.018787

1-sigma variation

Unit

Orbit Period

Value

726.7430

1-sigma variation

Unit

U parameter

Value

7.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.00026E-7	5.09596E-8	1.55025E-6	-7.00718E-6	5.25531E-6	-1.61467E-4
e	5.09596E-8	2.59621E-8	7.89790E-7	-3.56984E-6	2.67730E-6	-8.22614E-5
i	1.55025E-6	7.89790E-7	2.40269E-5	-1.08611E-4	8.14609E-5	-2.50248E-3
Ω	-7.00718E-6	-3.56984E-6	-1.08611E-4	4.91093E-4	-3.68388E-4	1.13113E-2
ω	5.25531E-6	2.67730E-6	8.14609E-5	-3.68388E-4	2.76373E-4	-8.48338E-3
M	-1.61467E-4	-8.22614E-5	-2.50248E-3	1.13113E-2	-8.48338E-3	2.60647E-1

Date of computation: 2026-07-30 14:25 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

25.372

Unit

mag

Source

[1]

Slope Parameter (G)

Value

0.15**

Unit

Source

[1]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[2]

Diameter

Value

22 - 50*

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

2102

Unit

Source

[1]

Normalized RMS of residuals

Value

0.522624

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2021-01-16.493849

Unit

Source

[2]

Last Observation

Value

2021-02-06.323097

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

65 (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

[-]

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

Filters

Initial Date: *

Final Date: *

Normalised Only accepted

Max residual (arcsec):

* - these fields are required

Plot

Computation parameters

As seen from:

Initial Date: *

Final Date: *

Output option:

One line per time step

Time step:*

* - these fields are required

Note: Ephemerides requests are limited to a maximum of 1000 points and a final date not exceeding 2040/12/31 00:00.

Close Approaches for 2021BJ from 1950 to 2126

Body	Date in UTC	Time uncert. in min	Nominal distance in au	Min. possible distance in au	Distance uncert. in au
EARTH	2017-02-01 23:46	1286.8	0.1883820	0.1417703	0.0155575
EARTH	2019-01-25 02:46	1200.2	0.0846372	0.0603287	0.0081826
EARTH	2021-01-12 21:48	< 1 min	0.0197989	0.0197583	0.0000135
EARTH	2022-12-28 11:34	> 1 d	0.0382034	0.0282853	0.0034876
EARTH	2024-12-03 01:45	> 1 d	0.0485652	0.0430429	0.0019240
EARTH	2026-11-11 20:30	> 1 d	0.0287326	0.0255610	0.0058767
EARTH	2028-10-30 12:16	> 1 d	0.0439751	0.0257602	0.0236286
EARTH	2030-10-21 09:57	> 1 d	0.1203899	0.0278058	0.0347735

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
21.11292076	6.40708958	0.01878680	MINIMUM
337.22591156	301.04228818	0.02568994	MINIMUM
358.47000726	332.69845267	0.04955692	SADDLE
179.54885091	154.10448596	1.20645677	SADDLE
358.94725851	153.43309462	1.95785694	SADDLE
179.58860505	334.13624166	3.20585173	MAXIMUM

Download:

MOID Plots

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