Asteroids

138971 2001CB21 help

Last update: 2025-11-04 13:15 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.689

Aphelion (Q)

1.378

Eccentricity (e)

0.333

Inclination (i)

7.9

deg

Orbit period (P)

383.8

Earth MOID

0.02422

U parameter

0.0

Next Earth close approach

Date

2026-09-29

Nominal distance (from Earth center)

0.05412

8096707

Maximum Brightness

15.8

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

18.5

mag

Diameter

500 - 1200*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2001-02-02

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

1.033573

1-sigma variation

3.698E-10

Unit

Eccentricity (e)

Value

0.333396

1-sigma variation

8.785E-9

Unit

Inclination (i)

Value

7.9183

1-sigma variation

1.544E-6

Unit

Long. of Ascending Node (Ω)

Value

353.6471

1-sigma variation

5.885E-6

Unit

Arg. of Perihelion (ω)

Value

271.9355

1-sigma variation

5.434E-6

Unit

Mean Anomaly (M)

Value

131.04917

1-sigma variation

2.281E-6

Unit

Perihelion distance

Value

0.688984

1-sigma variation

Unit

Aphelion distance

Value

1.378161

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.097378

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.066175

1-sigma variation

Unit

MOID

Value

0.024221

1-sigma variation

Unit

Orbit Period

Value

383.8044

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.36727E-19	-1.26698E-18	2.71489E-16	1.69338E-15	-1.66200E-15	-3.33925E-16
e	-1.26698E-18	7.71793E-17	5.71845E-15	-2.23185E-14	2.29065E-14	8.89093E-15
i	2.71489E-16	5.71845E-15	2.38275E-12	4.89735E-13	6.82863E-14	-1.82892E-13
Ω	1.69338E-15	-2.23185E-14	4.89735E-13	3.46333E-11	-2.98052E-11	-8.05605E-12
ω	-1.66200E-15	2.29065E-14	6.82863E-14	-2.98052E-11	2.95323E-11	4.23900E-12
M	-3.33925E-16	8.89093E-15	-1.82892E-13	-8.05605E-12	4.23900E-12	5.20343E-12

Date of computation: 2025-11-04 13:15 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

[1]

Taxonomy (all)

Value

Unit

Source

[2]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

18.513

Unit

mag

Source

[3]

Slope Parameter (G)

Value

0.15**

Unit

mag

Source

[3]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[4]

Diameter

Value

500 - 1200*

Unit

Source

[4]

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]	EARN	1.) Alexey V. Sergeyev and Benoit Carry A&A, 652 (2021) A59
[2]	EARN	Earth Asteroids Research Node: https://earn.dlr.de
[3]	ESA Aegis	ESA orbit determination and impact monitoring system
[4]	Estimation	Estimated from absolute magnitude

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

9040

Unit

Source

[1]

Unobserved

Value

Unit

Source

[1]

Normalized RMS of residuals

Value

0.460705

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2001-02-02.47394

Unit

Source

[2]

Last Observation

Value

2025-11-03.088015

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

2324 (20)

Unit

Source

[1]

Radar Summary

First Observation
Last Observation
Delay (Discarded)
Doppler (Discarded)
Total Optical Observations (Discarded)

Radar

Value

Unit

Source

First Observation

Value

2006-10-02

Unit

Source

[3]

Last Observation

Value

2006-10-02

Unit

Source

[3]

Delay (Discarded)

Value

1 (0)

Unit

Source

[1]

Doppler (Discarded)

Value

1 (0)

Unit

Source

[1]

Total Radar Observations (Discarded)

Value

2 (0)

Unit

Source

[1]

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
[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 138971 2001CB21 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
VENUS	1954-01-28 11:04	< 1 s	0.0483329	0.0483328	0.0000000
EARTH	1961-03-09 05:45	< 1 s	0.1062992	0.1062991	0.0000000
EARTH	1965-10-04 20:48	< 1 s	0.1017072	0.1017071	0.0000000
EARTH	1981-03-03 21:18	< 1 s	0.0340531	0.0340529	0.0000001
EARTH	1985-09-29 05:14	< 1 s	0.0481330	0.0481329	0.0000001
EARTH	2002-03-06 16:23	< 1 s	0.0450719	0.0450718	0.0000000
VENUS	2004-07-14 04:46	< 1 s	0.0397018	0.0397018	0.0000000
EARTH	2006-10-02 10:48	< 1 s	0.0478688	0.0478688	0.0000000
EARTH	2022-03-04 07:58	< 1 s	0.0328284	0.0328283	0.0000000
EARTH	2026-09-29 07:17	< 1 s	0.0541231	0.0541230	0.0000000
EARTH	2043-03-06 09:22	< 1 s	0.0321880	0.0321879	0.0000000
EARTH	2047-10-01 07:18	< 1 s	0.0359942	0.0359942	0.0000000
EARTH	2063-02-26 05:23	< 1 s	0.1735921	0.1735915	0.0000002
EARTH	2064-03-11 00:20	< 1 s	0.1488864	0.1488858	0.0000002
EARTH	2067-09-17 17:11	< 1 min	0.1839085	0.1839080	0.0000002
EARTH	2068-10-06 20:30	< 1 s	0.1411221	0.1411215	0.0000002
EARTH	2084-03-03 08:27	< 1 s	0.0434668	0.0434667	0.0000000
EARTH	2088-09-27 10:06	< 1 s	0.0799156	0.0799155	0.0000000
EARTH	2105-03-03 04:35	< 1 s	0.0735795	0.0735789	0.0000002
EARTH	2109-09-24 08:37	< 1 s	0.1476473	0.1476468	0.0000002
EARTH	2110-10-09 17:47	< 1 s	0.1627088	0.1627084	0.0000001

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
278.26511854	61.99076848	0.02422085	MINIMUM
82.53421686	267.42933567	0.03604816	MINIMUM
0.65393835	164.84548450	0.34828340	SADDLE
180.22784660	344.64994701	0.42554118	SADDLE
0.92639998	345.25708549	1.66926111	SADDLE
180.59742478	164.91683944	2.39011334	MAXIMUM

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MOID Plots

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