Asteroids

1981 Midas help

Last update: 2025-08-11 12:45 UTC

Orbital Properties

Epoch

60800.0

MJD

Orbit type

Apollo

Perihelion (q)

0.621

Aphelion (Q)

2.932

Eccentricity (e)

0.651

Inclination (i)

39.8

deg

Orbit period (P)

864.8

Earth MOID

0.00339

U parameter

0.0

Next Earth close approach

Date

2032-09-14

Nominal distance (from Earth center)

0.08635

12917837

Maximum Brightness

12.3

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

15.3

mag

Diameter

1900

Taxonomic type

Rotation period (T)

5.220

Discovery Information

Discovery Date

1973-03-06

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

60800.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.776403

1-sigma variation

2.252E-9

Unit

Eccentricity (e)

Value

0.650519

1-sigma variation

1.901E-8

Unit

Inclination (i)

Value

39.8232

1-sigma variation

4.700E-6

Unit

Long. of Ascending Node (Ω)

Value

356.7945

1-sigma variation

1.446E-6

Unit

Arg. of Perihelion (ω)

Value

267.8466

1-sigma variation

4.024E-6

Unit

Mean Anomaly (M)

Value

342.08157

1-sigma variation

2.401E-6

Unit

Perihelion distance

Value

0.620819

1-sigma variation

Unit

Aphelion distance

Value

2.931987

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.046299

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.004825

1-sigma variation

Unit

MOID

Value

0.003393

1-sigma variation

Unit

Orbit Period

Value

864.7901

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	5.07341E-18	-7.63878E-18	7.10336E-16	-4.88732E-16	-2.28928E-16	-4.91306E-15
e	-7.63878E-18	3.61294E-16	-1.21937E-14	1.55134E-14	2.80668E-14	1.61792E-14
i	7.10336E-16	-1.21937E-14	2.20935E-11	7.49327E-13	8.10728E-13	-1.85647E-12
Ω	-4.88732E-16	1.55134E-14	7.49327E-13	2.09220E-12	-2.98398E-12	1.77169E-12
ω	-2.28928E-16	2.80668E-14	8.10728E-13	-2.98398E-12	1.61908E-11	-2.36171E-12
M	-4.91306E-15	1.61792E-14	-1.85647E-12	1.77169E-12	-2.36171E-12	5.76476E-12

Date of computation: 2025-08-11 12:45 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

5.220

Unit

Source

[3]

Quality

Value

Unit

Source

[3]

Amplitude

Value

0.65-0.87

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

S;V

Unit

Source

[2]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

15.29

15.6

Unit

mag

Source

[4]

[5]

Slope Parameter (G)

Value

0.15**

0.23

Unit

mag

Source

[4]

[6]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.293

Unit

Source

[8]

Diameter

Value

1900

Unit

Source

[7]

Color Index Information

Color Index Information

Value

Unit

Source

Color Index Information

Value

0.48

0.97

Unit

U-B

B-V

Source

[9]

Sightings

Sightings

Value

Unit

Source

Sightings

Value

Radar R

Visual S

Unit

Source

[10]

[11]

Download this part as:

Sources

No.	Name	Additional
[1]	EARN	1.) 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.)
[2]	EARN	1.) Mottola, S. et al. (1995) Icarus 117, 62-70. (The near-earth objects follow-up program: First results.)(1981, 2062,4953,5633,5797,5836,1993BX3,1994AW1,1994JF1,1994LC1) 2.) 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.) 3.) 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]	EARN	1.) Mottola, S. et al. (1995) Icarus 117, 62-70. (The near-earth objects follow-up program: First results.)(1981, 2062,4953,5633,5797,5836,1993BX3,1994AW1,1994JF1,1994LC1) 2.) Wisniewski, W.Z. et al. (1997) Icarus 126, 395-449. (Photometric Observations of 125 Asteroids) 3.) Franco, L. et al. (2018) MPB 45, 273-275. (Lightcurves for 1318 Nerina, 1342 Brabantia, 1981 Midas, and 3951 Zichichi)
[4]	ESA Aegis	ESA orbit determination and impact monitoring system
[5]	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) 2.) Mottola, S. et al. (1995) Icarus 117, 62-70. (The near-earth objects follow-up program: First results.)(1981, 2062,4953,5633,5797,5836,1993BX3,1994AW1,1994JF1,1994LC1) 3.) Wisniewski, W.Z. et al. (1997) Icarus 126, 395-449. (Photometric Observations of 125 Asteroids)
[6]	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) 2.) Wisniewski, W.Z. et al. (1997) Icarus 126, 395-449. (Photometric Observations of 125 Asteroids)
[7]	EARN	1.) Usui, F. et al. (2011) Pub. Astron. Soc. Japan 63, 1117-1138. (Asteroid Catalog Using AKARI: AKARI/IRC Mid-Infrared Asteroid Survey)
[8]	EARN	1.) Usui, F. et al. (2011) Pub. Astron. Soc. Japan 63, 1117-1138. (Asteroid Catalog Using AKARI: AKARI/IRC Mid-Infrared Asteroid Survey) 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)
[9]	EARN	1.) Mottola, S. et al. (1995) Icarus 117, 62-70. (The near-earth objects follow-up program: First results.)(1981, 2062,4953,5633,5797,5836,1993BX3,1994AW1,1994JF1,1994LC1)
[10]	EARN	1.) href="http://echo.jpl.nasa.gov/asteroids/index.html">JPL's NEO Radar Detection Program Webpage 2.) Ostro, S.J. et al. (1991) Astron. J. 102, 1490-1502. (Asteroid radar astrometry)
[11]	EARN	1.) Binzel, R.P. et al. (2001) Icarus 151,139-149. (Spectral Properties of Near-Earth Objects: Palomar and IRTF Results for 48 Objects Including Spacecraft Targets (9969) Braille and (10302) 1989 ML)

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

19150

Unit

Source

[1]

Unobserved

Value

Unit

Source

[1]

Normalized RMS of residuals

Value

0.438287

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1973-03-06.28299

Unit

Source

[2]

Last Observation

Value

2025-08-10.623053

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

1946 (18)

Unit

Source

[1]

Radar Summary

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

Radar

Value

Unit

Source

First Observation

Value

1987-09-25

Unit

Source

[3]

Last Observation

Value

2018-03-25

Unit

Source

[3]

Delay (Discarded)

Value

6 (0)

Unit

Source

[1]

Doppler (Discarded)

Value

1 (0)

Unit

Source

[1]

Total Radar Observations (Discarded)

Value

7 (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 1981 Midas 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	1961-09-12 11:13	< 1 min	0.1504010	0.1504001	0.0000003
EARTH	1987-09-21 09:15	< 1 min	0.0692739	0.0692730	0.0000003
EARTH	1992-03-11 16:48	< 1 min	0.1333216	0.1333208	0.0000003
EARTH	2018-03-21 21:19	< 1 s	0.0895720	0.0895719	0.0000000
EARTH	2032-09-14 14:56	< 1 s	0.0863504	0.0863498	0.0000002
EARTH	2058-09-23 07:59	< 1 min	0.1199244	0.1199233	0.0000004
EARTH	2063-03-14 10:16	< 1 min	0.0824880	0.0824869	0.0000003
EARTH	2089-03-20 13:59	< 1 s	0.0723279	0.0723276	0.0000001
EARTH	2103-09-14 00:45	< 1 s	0.1337685	0.1337681	0.0000001

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
312.35807633	73.82835415	0.00339301	MINIMUM
49.51868768	253.88435090	0.03159423	MINIMUM
1.10929215	164.35789643	0.66969048	SADDLE
0.83202504	343.56442153	1.51430529	SADDLE
180.61282808	342.24939003	2.26505895	SADDLE
179.74907466	161.73985203	3.76871000	MAXIMUM

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MOID Plots

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