Asteroids

2021TP21 help

Last update: 2026-06-04 23:11 UTC

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.812

Aphelion (Q)

4.225

Eccentricity (e)

0.678

Inclination (i)

25.4

deg

Orbit period (P)

1459.8

Earth MOID

0.03411

U parameter

0.0

Next Earth close approach

Date

2101-03-15

Nominal distance (from Earth center)

0.17774

26589009

Maximum Brightness

19.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

20.1

mag

Diameter

250 - 600*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

2021-10-11

Observatory

University of Arizona Mt. Lemmon Survey

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

2.518475

1-sigma variation

2.416E-8

Unit

Eccentricity (e)

Value

0.677543

1-sigma variation

3.574E-7

Unit

Inclination (i)

Value

25.4164

1-sigma variation

1.632E-5

Unit

Long. of Ascending Node (Ω)

Value

8.0492

1-sigma variation

2.163E-5

Unit

Arg. of Perihelion (ω)

Value

116.3226

1-sigma variation

0.0001

Unit

Mean Anomaly (M)

Value

43.10418

1-sigma variation

0.00001

Unit

Perihelion distance

Value

0.812101

1-sigma variation

Unit

Aphelion distance

Value

4.224849

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.945846

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.049490

1-sigma variation

Unit

MOID

Value

0.034112

1-sigma variation

Unit

Orbit Period

Value

1459.8388

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	5.83599E-16	3.26584E-15	1.75304E-13	2.55570E-13	8.40953E-13	-2.11373E-13
e	3.26584E-15	1.27720E-13	-4.63310E-13	2.61845E-12	2.71262E-11	-1.66362E-12
i	1.75304E-13	-4.63310E-13	2.66203E-10	2.73475E-10	-1.66721E-10	-6.79707E-11
Ω	2.55570E-13	2.61845E-12	2.73475E-10	4.67988E-10	3.72771E-10	-1.10036E-10
ω	8.40953E-13	2.71262E-11	-1.66721E-10	3.72771E-10	6.11598E-9	-4.23349E-10
M	-2.11373E-13	-1.66362E-12	-6.79707E-11	-1.10036E-10	-4.23349E-10	8.63954E-11

Date of computation: 2026-06-04 23:11 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

20.107

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

250 - 600*

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

2969

Unit

Source

[1]

Unobserved

Value

285

Unit

Source

[1]

Normalized RMS of residuals

Value

0.688999

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2017-08-04.594249

Unit

Source

[2]

Last Observation

Value

2025-09-20.597043

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

76 (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:

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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 2021TP21 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	2101-03-15 00:41	1.2	0.1777365	0.1777087	0.0000093

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
28.71342476	82.95820188	0.03309769	MINIMUM
324.70471383	308.93514057	0.34823069	MINIMUM
349.33099082	359.27512896	0.42445875	SADDLE
357.99610399	200.10882790	1.79229632	SADDLE
178.59955719	204.90632011	3.31061372	SADDLE
181.06874672	26.05507149	5.14874815	MAXIMUM

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MOID Plots

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