Asteroids

2025SY21 help

Last update: 2025-09-30 20:00 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.590

Aphelion (Q)

3.532

Eccentricity (e)

0.714

Inclination (i)

1.4

deg

Orbit period (P)

1080.5

Earth MOID

0.01073

U parameter

7.8

Next Earth close approach

Date

2025-10-01

Nominal distance (from Earth center)

0.01142

1708651

Maximum Brightness

19.7

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

26.9

mag

Diameter

11 - 25*

Taxonomic type

Rotation period (T)

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

2.060736

1-sigma variation

0.002491

Unit

Eccentricity (e)

Value

0.713814

1-sigma variation

0.000411

Unit

Inclination (i)

Value

1.3566

1-sigma variation

0.0014

Unit

Long. of Ascending Node (Ω)

Value

215.1260

1-sigma variation

0.0245

Unit

Arg. of Perihelion (ω)

Value

242.3719

1-sigma variation

0.0232

Unit

Mean Anomaly (M)

Value

1.17844

1-sigma variation

0.00239

Unit

Perihelion distance

Value

0.589753

1-sigma variation

Unit

Aphelion distance

Value

3.531719

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.505524

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

-0.234805

1-sigma variation

Unit

MOID

Value

0.010731

1-sigma variation

Unit

Orbit Period

Value

1080.5176

1-sigma variation

Unit

U parameter

Value

7.8

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	6.20660E-6	1.02344E-6	2.70767E-6	-2.10117E-5	1.90293E-5	5.95111E-6
e	1.02344E-6	1.68779E-7	4.42749E-7	-3.37027E-6	3.04832E-6	9.81163E-7
i	2.70767E-6	4.42749E-7	2.01244E-6	-3.01172E-5	2.83042E-5	2.62729E-6
Ω	-2.10117E-5	-3.37027E-6	-3.01172E-5	5.99316E-4	-5.68612E-4	-2.09317E-5
ω	1.90293E-5	3.04832E-6	2.83042E-5	-5.68612E-4	5.39784E-4	1.89943E-5
M	5.95111E-6	9.81163E-7	2.62729E-6	-2.09317E-5	1.89943E-5	5.70732E-6

Date of computation: 2025-09-30 20:00 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

26.912

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

11 - 25*

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

0.9

Unit

Source

[1]

Unobserved

Value

Unit

Source

[1]

Normalized RMS of residuals

Value

0.824781

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

2025-09-29.479565

Unit

Source

[2]

Last Observation

Value

2025-09-30.379748

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

19 (2)

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 2025SY21 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	1955-03-29 10:33	> 1 w	0.0407055	0.0118173	0.1563942
EARTH	1966-10-16 15:49	> 1 mo	0.1873736	0.0127545	0.3774706
EARTH	1969-09-24 07:05	> 1 w	0.1286587	0.0113221	0.4415223
MARS	1993-09-11 17:50	> 1 w	0.0386979	0.0092698	0.2311147
EARTH	2011-03-28 15:00	> 1 w	0.0188216	0.0113875	0.0983884
EARTH	2025-10-01 20:06	< 1 min	0.0114210	0.0114048	0.0000054
EARTH	2085-04-04 15:32	> 1 w	0.1593506	0.0109524	0.3035694
EARTH	2088-03-24 21:30	> 1 w	0.0278225	0.0109761	0.2386919
EARTH	2105-10-10 13:49	> 1 mo	0.0978186	0.0098003	1.1631993
EARTH	2108-09-28 19:24	> 1 mo	0.0836334	0.0096841	1.2675085

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
316.08659254	267.96276510	0.01073085	MINIMUM
43.81943319	84.30216443	0.01132002	MINIMUM
359.92228396	356.10777891	0.39415177	SADDLE
359.89229711	176.04034467	1.60779896	SADDLE
179.98647841	176.16109202	2.51409540	SADDLE
179.97903747	356.15868897	4.51532422	MAXIMUM

Download:

MOID Plots

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