Asteroids

37655 Illapa help

Last update: 2025-09-10 00:30 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.366

Aphelion (Q)

2.590

Eccentricity (e)

0.752

Inclination (i)

18.0

deg

Orbit period (P)

656.1

Earth MOID

0.02468

U parameter

0.0

A₂

-13.3

10^-15au/days²

Next Earth close approach

Date

2091-08-24

Nominal distance (from Earth center)

0.18426

27565190

Maximum Brightness

16.6

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

17.8

mag

Diameter

700 - 1600*

Taxonomic type

Rotation period (T)

2.656

Discovery Information

Discovery Date

1994-08-01

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

61000.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.477749

1-sigma variation

4.372E-9

Unit

Eccentricity (e)

Value

0.752446

1-sigma variation

1.913E-8

Unit

Inclination (i)

Value

18.0332

1-sigma variation

4.573E-6

Unit

Long. of Ascending Node (Ω)

Value

139.5124

1-sigma variation

5.284E-6

Unit

Arg. of Perihelion (ω)

Value

303.9177

1-sigma variation

5.928E-6

Unit

Mean Anomaly (M)

Value

114.45025

1-sigma variation

0.00001

Unit

Perihelion distance

Value

0.365823

1-sigma variation

Unit

Aphelion distance

Value

2.589675

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.535645

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.090835

1-sigma variation

Unit

MOID

Value

0.024675

1-sigma variation

Unit

Orbit Period

Value

656.1443

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

A₂

Value

-13.25019

1-sigma variation

2.93394

Unit

10^-15au/days²

Covariance Matrix

	a	e	i	Ω	ω	M	A₂
a	1.91143E-17	3.18573E-17	-2.32688E-15	3.90949E-15	-1.81175E-15	-3.09479E-14	1.27722E-8
e	3.18573E-17	3.65818E-16	1.07034E-14	1.27721E-15	1.29648E-14	-2.25453E-14	2.29952E-8
i	-2.32688E-15	1.07034E-14	2.09115E-11	-2.20386E-12	1.74960E-12	5.10121E-12	-1.75995E-6
Ω	3.90949E-15	1.27721E-15	-2.20386E-12	2.79211E-11	-2.61910E-11	-5.52693E-12	3.25570E-6
ω	-1.81175E-15	1.29648E-14	1.74960E-12	-2.61910E-11	3.51358E-11	-1.79593E-12	-1.80141E-6
M	-3.09479E-14	-2.25453E-14	5.10121E-12	-5.52693E-12	-1.79593E-12	5.54799E-11	-2.03941E-5
A₂	1.27722E-8	2.29952E-8	-1.75995E-6	3.25570E-6	-1.80141E-6	-2.03941E-5	8.60799E0

Date of computation: 2025-09-10 00:30 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

2.656

Unit

Source

[1]

Quality

Value

Unit

Source

[1]

Amplitude

Value

0.11

Unit

mag

Source

[1]

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

18.01

17.83

Unit

mag

Source

[2]

[3]

Slope Parameter (G)

Value

0.24

0.15**

Unit

mag

Source

[2]

[3]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[4]

Diameter

Value

700 - 1600*

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

Radar R

Unit

Source

[5]

Download this part as:

Sources

No.	Name	Additional
[1]	EARN	1.) Petr Pravec's Ondrejov NEO Photometric Program Webpage "Prepublished Periods" 2.) R. Behrend Courbes des lumiere, Observatoire de Geneve website
[2]	EARN	1.) Pravec, P. et al. (2012) Icarus 221, 365-387 (Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations)
[3]	ESA Aegis	ESA orbit determination and impact monitoring system
[4]	Estimation	Estimated from absolute magnitude
[5]	EARN	1.) href="http://echo.jpl.nasa.gov/asteroids/index.html">JPL's NEO Radar Detection Program Webpage

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

10923

Unit

Source

[1]

Unobserved

Value

476

Unit

Source

[1]

Normalized RMS of residuals

Value

0.443052

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1994-08-01.32864

Unit

Source

[2]

Last Observation

Value

2024-06-27.383947

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

664 (5)

Unit

Source

[1]

Radar Summary

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

Radar

Value

Unit

Source

First Observation

Value

2003-08-19

Unit

Source

[3]

Last Observation

Value

2012-08-13

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 37655 Illapa 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	1985-08-21 05:27	< 1 s	0.1184536	0.1184530	0.0000002
EARTH	1994-08-18 08:15	< 1 s	0.0443812	0.0443809	0.0000001
EARTH	2003-08-16 14:12	< 1 s	0.0250376	0.0250375	0.0000000
EARTH	2012-08-12 07:53	< 1 s	0.0951452	0.0951452	0.0000000
EARTH	2021-08-08 07:46	< 1 s	0.1910413	0.1910409	0.0000001
EARTH	2091-08-24 15:51	< 1 min	0.1842619	0.1842518	0.0000034
EARTH	2100-08-21 16:43	< 1 min	0.0999309	0.0999208	0.0000034
EARTH	2109-08-19 04:32	< 1 min	0.0420620	0.0420554	0.0000022
EARTH	2118-08-17 06:30	< 1 min	0.0434352	0.0434252	0.0000033

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
294.36382557	222.06058173	0.02499727	MINIMUM
59.79583572	92.47775925	0.26576472	MINIMUM
355.78005595	332.25838067	0.64084711	SADDLE
357.52499970	156.86780924	1.37129423	SADDLE
178.46354414	161.83596720	1.62955037	SADDLE
180.54855577	342.64255214	3.55003947	MAXIMUM

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MOID Plots

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