Asteroids

4341 Poseidon help

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

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.587

Aphelion (Q)

3.082

Eccentricity (e)

0.680

Inclination (i)

11.8

deg

Orbit period (P)

907.3

Earth MOID

0.19419

U parameter

0.0

Next Earth close approach

Date

2118-11-05

Nominal distance (from Earth center)

0.19586

29300468

Maximum Brightness

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

16.1

mag

Diameter

3100

Taxonomic type

Rotation period (T)

6.262

Discovery Information

Discovery Date

1987-05-29

Observatory

Palomar Mountain

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

1.834085

1-sigma variation

3.668E-9

Unit

Eccentricity (e)

Value

0.680149

1-sigma variation

3.645E-8

Unit

Inclination (i)

Value

11.8400

1-sigma variation

4.170E-6

Unit

Long. of Ascending Node (Ω)

Value

108.0227

1-sigma variation

1.798E-5

Unit

Arg. of Perihelion (ω)

Value

15.8426

1-sigma variation

1.837E-5

Unit

Mean Anomaly (M)

Value

282.03691

1-sigma variation

0.00001

Unit

Perihelion distance

Value

0.586633

1-sigma variation

Unit

Aphelion distance

Value

3.081537

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.387727

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

1.834141

1-sigma variation

Unit

MOID

Value

0.194193

1-sigma variation

Unit

Orbit Period

Value

907.2514

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	1.34554E-17	-9.32025E-17	4.65235E-15	7.51858E-15	-5.89726E-15	-2.55786E-14
e	-9.32025E-17	1.32865E-15	-2.32367E-14	-2.03713E-14	4.89017E-15	2.21628E-13
i	4.65235E-15	-2.32367E-14	1.73890E-11	2.16504E-11	-1.73060E-11	-1.41781E-11
Ω	7.51858E-15	-2.03713E-14	2.16504E-11	3.23295E-10	-3.20277E-10	-5.49033E-12
ω	-5.89726E-15	4.89017E-15	-1.73060E-11	-3.20277E-10	3.37354E-10	-2.00824E-11
M	-2.55786E-14	2.21628E-13	-1.41781E-11	-5.49033E-12	-2.00824E-11	8.86130E-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

6.262

Unit

Source

[5]

Quality

Value

Unit

Source

[5]

Amplitude

Value

0.08

Unit

mag

Source

[5]

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]

[2]

Taxonomy (all)

Value

Unit

Source

[3]

[4]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

16.113

Unit

mag

Source

[6]

Slope Parameter (G)

Value

0.15**

Unit

Source

[6]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.0545

Unit

Source

[7]

Diameter

Value

3100

Unit

Source

[7]

Color Index Information

Color Index Information

Value

Unit

Source

Color Index Information

Value

Unit

mag

Source

[-]

Sightings

Sightings

Value

Unit

Source

Sightings

Value

Visual S

Unit

Source

[8]

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Sources

No.	Name	Additional
[1]	EARN	1.) Bus, S.J. & Binzel, R.P. (2002) Icarus 158,106-145. (Phase II of the Small Main-Belt Asteroid Spectrographic Survey: A Feature-Based Taxonomy.)
[2]	EARN	1.) Michaël Marsset et al 2022 AJ 163 165
[3]	EARN	1.) Bus, S.J. & Binzel, R.P. (2002) Icarus 158,106-145. (Phase II of the Small Main-Belt Asteroid Spectrographic Survey: A Feature-Based Taxonomy.) 2.) Binzel, R.P. et al. (2004) Icarus 170, 259-294. (Observed spectral properties of near-Earth objects: results for population distribution, source regions, and space weathering processes.)
[4]	EARN	Earth Asteroids Research Node: https://earn.dlr.de
[5]	EARN	1.) Petr Pravec's Ondrejov NEO Photometric Program Webpage "Prepublished Periods" 2.) Pravec, P. et al. (1998) Icarus 136, 124-153. (Lightcurves of 26 Near-Earth Asteroids)(1943,2063,2100,3103,3122,3200, 3691,3752,4341,4957,5143,5587,7025,7341,7480,7482,7822,8034, 1989UQ,1992CC1,1992QN,1995FX,1997BR,1997GH3,1997GL3,1997SE5) 3.) Krugly, Yu.N. et al. (2002) Icarus 158, 294-304. (The Near-Earth Objects Follow-up Program. IV. CCD Photometry in 1996-1999).
[6]	ESA Aegis	ESA orbit determination and impact monitoring system
[7]	EARN	1.) Masiero, J.R. et al. (2018) Astron. J. 154_168(10pp). (NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos) (170NEOs, 6110MBAs) 2.) Binzel, R.P. et al. (2002) in "Asteroids III" (Eds. W.F.Bottke et al.), Univ.Ariz.Press, Tucson, USA, pp. 255-271. (Physical Properties of NEOs)
[8]	EARN	1.) Bus, S.J. & Binzel, R.P. (2002) Icarus 158,106-145. (Phase II of the Small Main-Belt Asteroid Spectrographic Survey: A Feature-Based Taxonomy.) 2.) Binzel, R.P. et al. (2004) Icarus 170, 259-294. (Observed spectral properties of near-Earth objects: results for population distribution, source regions, and space weathering processes.) 3.) Fevig. R.A. and U. Fink (2007) Icarus 188, 175-188. (Spectral observations of 19 weathered and 23 fresh NEAs and their correlations with orbital parameters)(433,1036, 1627,1685,1862,1866,1943,1980,3103,3122,3199,3671,4183,4341, 4954,5587,5751,5836,6037,7358,7482,7753,7822,7977,8201, 10563,11066,13651,13651,19356,20236,20255,35107,85490, J97GD32,J97UH9,J97US9,J98HE3,J98HT31,J98ME3,J98MS2,K04LC2)

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

13943

Unit

Source

[1]

Unobserved

Value

310

Unit

Source

[1]

Normalized RMS of residuals

Value

0.517188

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1987-05-29.2467

Unit

Source

[2]

Last Observation

Value

2025-07-31.377777

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

846 (3)

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

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 4341 Poseidon 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	2118-11-05 19:01	< 1 min	0.1958615	0.1958598	0.0000006

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
314.90702920	293.61614759	0.19419254	MINIMUM
48.27288637	110.42791169	0.19769469	MINIMUM
3.07731057	25.37782935	0.40133571	SADDLE
1.12587394	201.07618506	1.60177292	SADDLE
180.45034934	199.43543291	2.06804897	SADDLE
179.94076191	19.21277510	4.06478349	MAXIMUM

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MOID Plots

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