Asteroids

31669 1999JT6 help

Last update: 2026-10-11 13:30 UTC

Orbital Properties

Epoch

61400.0

MJD

Orbit type

Apollo

Perihelion (q)

0.902

Aphelion (Q)

3.372

Eccentricity (e)

0.578

Inclination (i)

9.5

deg

Orbit period (P)

1141.0

Earth MOID

0.00098

U parameter

0.0

Next Earth close approach

Date

2027-02-18

Nominal distance (from Earth center)

0.15673

23446090

Maximum Brightness

15.6

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

16.2

mag

Diameter

1600 - 3000*

Taxonomic type

Rotation period (T)

5.806

Discovery Information

Discovery Date

1999-05-12

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

61400.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

2.136943

1-sigma variation

1.777E-9

Unit

Eccentricity (e)

Value

0.577888

1-sigma variation

2.155E-8

Unit

Inclination (i)

Value

9.5370

1-sigma variation

3.399E-6

Unit

Long. of Ascending Node (Ω)

Value

78.7523

1-sigma variation

2.161E-5

Unit

Arg. of Perihelion (ω)

Value

39.1396

1-sigma variation

2.183E-5

Unit

Mean Anomaly (M)

Value

349.71284

1-sigma variation

3.841E-6

Unit

Perihelion distance

Value

0.902030

1-sigma variation

Unit

Aphelion distance

Value

3.371857

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.001750

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

1.565168

1-sigma variation

Unit

MOID

Value

0.000977

1-sigma variation

Unit

Orbit Period

Value

1141.0060

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	3.15835E-18	-1.81643E-17	-2.76097E-16	1.23997E-15	2.72240E-15	-5.34688E-15
e	-1.81643E-17	4.64293E-16	-4.21471E-15	-7.72203E-15	-1.19821E-14	2.53172E-14
i	-2.76097E-16	-4.21471E-15	1.15520E-11	-2.14218E-11	2.11995E-11	-9.48542E-14
Ω	1.23997E-15	-7.72203E-15	-2.14218E-11	4.66893E-10	-4.62233E-10	2.72699E-12
ω	2.72240E-15	-1.19821E-14	2.11995E-11	-4.62233E-10	4.76483E-10	-1.54006E-11
M	-5.34688E-15	2.53172E-14	-9.48542E-14	2.72699E-12	-1.54006E-11	1.47497E-11

Date of computation: 2026-10-11 13:30 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

5.806

Unit

Source

[3]

Quality

Value

Unit

Source

[3]

Amplitude

Value

0.07-0.27

Unit

mag

Source

[3]

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

Q,Sq

Unit

Source

[2]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

16.164

Unit

mag

Source

[4]

Slope Parameter (G)

Value

0.15**

Unit

Source

[4]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[5]

Diameter

Value

1600 - 3000*

Unit

Source

[5]

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.) DeMeo, F.E. et al. (2014) Icarus 227, 112-122. (Mars encounters cause fresh surfaces on some near-Earth asteroids) (contains taxonomic classification of 249 NEAs)
[2]	EARN	1.) Thomas, C.A. et al. (2014) Icarus 228, 217-246. (Physical characterization of Warm Spitzer-observed near-Earth objects) 2.) DeMeo, F.E. et al. (2014) Icarus 227, 112-122. (Mars encounters cause fresh surfaces on some near-Earth asteroids) (contains taxonomic classification of 249 NEAs)
[3]	EARN	1.) Galad, A. et al. (2005) Earth, Moon and Planets 97, 147-163. (Joint lightcurve observations of 10 near-Earth asteroids from Modra and Ondrejov) (3553,22753,31669,40267, 66146,88188,103067,1001CB21,2004LJ1,2004XO14,) 2.) Petr Pravec's Ondrejov NEO Photometric Program Webpage "Prepublished Periods"
[4]	ESA Aegis	ESA orbit determination and impact monitoring system
[5]	Estimation	Estimated from absolute magnitude

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

11077

Unit

Source

[1]

Unobserved

Value

Unit

Source

[1]

Normalized RMS of residuals

Value

0.579417

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1996-06-12.51984

Unit

Source

[2]

Last Observation

Value

2026-10-10.881833

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

1774 (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

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Max residual (arcsec):

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Computation parameters

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Final Date: *

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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 31669 1999JT6 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	1973-12-14 19:29	< 1 min	0.0338388	0.0338379	0.0000003
EARTH	2002-03-09 15:50	< 1 min	0.1906492	0.1906490	0.0000001
EARTH	2027-02-18 09:30	< 1 min	0.1567274	0.1567272	0.0000001
EARTH	2051-12-31 09:29	< 1 min	0.1003917	0.1003910	0.0000002
EARTH	2076-12-14 21:02	< 1 min	0.0269891	0.0269882	0.0000003
1 Ceres	2084-02-16 11:37	< 1 min	0.0170928	0.0170913	0.0000005
EARTH	2102-03-05 14:07	< 1 min	0.1666405	0.1666368	0.0000012
EARTH	2123-12-03 16:24	1.1	0.0822528	0.0822257	0.0000090

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
338.98818956	335.86317899	0.00097671	MINIMUM
0.98831673	196.16302721	1.91370855	SADDLE
180.56836332	194.90700088	2.36540337	SADDLE
179.84626425	14.53078573	4.35148395	MAXIMUM

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MOID Plots

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