Asteroids

1991BA help

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

Orbital Properties

Epoch

61200.0

MJD

Orbit type

Apollo

Perihelion (q)

0.701

Aphelion (Q)

3.498

Eccentricity (e)

0.666

Inclination (i)

2.1

deg

Orbit period (P)

1111.1

Earth MOID

0.00042

U parameter

9.0

Next Earth close approach

Date

2055-01-09

Nominal distance (from Earth center)

0.18608

27837392

Maximum Brightness

27.9

mag

Risk

Object is in risk list

Physical Properties

Absolute Magnitude (H)

28.7

mag

Diameter

5 - 11*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

1991-01-18

Observatory

Steward Observatory, Kitt Peak-Spacewatch

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

2.099418

1-sigma variation

0.002519

Unit

Eccentricity (e)

Value

0.666286

1-sigma variation

0.033354

Unit

Inclination (i)

Value

2.0857

1-sigma variation

0.5823

Unit

Long. of Ascending Node (Ω)

Value

117.3508

1-sigma variation

11.2150

Unit

Arg. of Perihelion (ω)

Value

74.3748

1-sigma variation

7.9421

Unit

Mean Anomaly (M)

Value

210.13023

1-sigma variation

258.21100

Unit

Perihelion distance

Value

0.700605

1-sigma variation

Unit

Aphelion distance

Value

3.498231

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

0.006296

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.405446

1-sigma variation

Unit

MOID

Value

0.000417

1-sigma variation

Unit

Orbit Period

Value

1111.0837

1-sigma variation

Unit

U parameter

Value

9.0

1-sigma variation

Unit

Covariance Matrix

	a	e	i	Ω	ω	M
a	6.34714E-6	8.40295E-5	-1.46695E-3	2.82544E-2	-2.00088E-2	6.50523E-1
e	8.40295E-5	1.11251E-3	-1.94205E-2	3.74064E-1	-2.64894E-1	8.61239E0
i	-1.46695E-3	-1.94205E-2	3.39048E-1	-6.53010E0	4.62447E0	-1.50347E2
Ω	2.82544E-2	3.74064E-1	-6.53010E0	1.25775E2	-8.90693E1	2.89583E3
ω	-2.00088E-2	-2.64894E-1	4.62447E0	-8.90693E1	6.30763E1	-2.05071E3
M	6.50523E-1	8.61239E0	-1.50347E2	2.89583E3	-2.05071E3	6.66730E4

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

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

28.74

Unit

mag

Source

[1]

Slope Parameter (G)

Value

0.15**

Unit

Source

[1]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[2]

Diameter

Value

5 - 11*

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

[-]

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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

0.2

Unit

Source

[1]

Unobserved

Value

12943

Unit

Source

[1]

Normalized RMS of residuals

Value

0.0926681

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1991-01-18.2262

Unit

Source

[2]

Last Observation

Value

1991-01-18.41914

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

7 (0)

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

Filters

Initial Date: *

Final Date: *

Normalised Only accepted

Max residual (arcsec):

* - these fields are required

Plot

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 1991BA 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	1965-06-12 06:53	> 1 mo	0.0378999	0.0196768	17.4992372
EARTH	1991-01-18 17:18	< 1 min	0.0011242	0.0009615	0.0000542
EARTH	2000-06-14 09:52	> 1 mo	0.0637111	0.0185497	7.7216074
EARTH	2003-07-01 04:22	> 1 mo	0.1805038	0.0181634	9.1336730
VENUS	2027-09-17 11:43	> 1 mo	0.0223519	0.0063990	3.2131703
EARTH	2055-01-09 17:50	> 1 mo	0.1860815	0.0011237	79.1744287
EARTH	2058-02-05 15:53	> 1 mo	0.1490409	0.0009454	73.0410143
EARTH	2064-06-06 05:51	> 1 mo	0.1218051	0.0175137	75.9217590
VENUS	2110-02-03 09:33	> 1 mo	0.0316280	0.0212682	11.3088692
EARTH	2113-01-16 18:18	> 1 mo	0.0496571	0.0008969	14.6421047
EARTH	2116-02-04 10:21	> 1 mo	0.1451101	0.0015919	3.0243397

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Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
322.88803808	16.40679140	0.00044928	MINIMUM
39.38340595	167.50822710	0.01755453	MINIMUM
1.64704781	92.67750496	0.30163042	SADDLE
1.59220492	272.55701828	1.70100055	SADDLE
180.32589179	270.84073435	2.49858322	SADDLE
180.31275289	90.83499231	4.49865664	MAXIMUM

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MOID Plots

Click on the images to zoom-in and zoom-out

Level lines of the squared distance function

1991BA

Date in UTC	MJD	σ	σ_imp	Distance ± Width in RE	Stretching in RE	IP	Impact energy	PS
2026-01-17.658	61057.658	0.225	0.494	1.16 ± 48.969	2.52E6	2.55E-9	1.97E-2	-8.31
2027-01-19.190	61424.190	-3.669	0.000	0.54 ± 0.013	3.13E5	3.45E-9	4.70E-3	-9.07
2032-01-19.735	63250.735	-1.389	0.000	0.26 ± 0.049	5.84E5	6.15E-7	9.33E-3	-7.16
2036-01-19.840	64711.840	-1.121	0.000	0.44 ± 0.516	5.97E6	7.48E-8	1.05E-2	-8.23
2038-01-18.946	65441.946	-4.200	0.000	0.66 ± 0.037	2.73E5	4.72E-10	4.15E-3	-10.82
2041-01-18.727	66537.727	-3.292	0.000	0.94 ± 0.044	2.41E5	1.45E-8	5.18E-3	-9.34
2042-01-18.515	66902.515	0.279	0.000	0.98 ± 0.171	3.65E7	2.13E-8	2.06E-2	-8.73
2044-01-20.101	67634.101	-1.568	0.000	0.34 ± 0.333	2.56E5	1.05E-6	8.78E-3	-7.38
2048-01-19.671	69094.671	-4.278	0.000	0.64 ± 0.051	7.26E5	1.46E-10	4.08E-3	-11.59
2052-01-19.730	70555.730	-1.092	0.000	1.20 ± 0.250	9.44E5	1.63E-7	1.06E-2	-8.28
2053-01-18.902	70920.902	-0.584	0.000	1.00 ± 0.214	4.18E6	1.81E-7	1.32E-2	-8.17
2056-01-19.703	72016.703	-2.877	0.000	0.71 ± 0.079	3.52E6	4.43E-9	5.80E-3	-10.11
2061-01-19.419	73843.419	-1.308	0.000	0.85 ± 0.268	1.88E6	2.09E-7	9.62E-3	-8.33
2066-01-19.320	75669.320	-3.067	0.000	0.52 ± 0.045	7.04E6	1.17E-9	5.50E-3	-10.83
2073-01-19.095	78226.095	-3.379	0.000	0.77 ± 0.053	2.16E5	1.50E-8	5.06E-3	-9.82
2075-01-20.315	78957.315	-0.936	1.796	1.20 ± 1.431	2.87E5	1.85E-9	1.13E-2	-10.47
2077-01-19.791	79687.791	-1.568	0.000	0.98 ± 1.056	3.14E7	4.46E-9	8.79E-3	-10.19
2078-01-19.772	80052.772	-1.426	0.000	0.69 ± 0.164	3.55E5	7.89E-7	9.21E-3	-7.94
2078-01-19.774	80052.774	-1.425	0.000	0.87 ± 0.169	3.46E5	8.05E-7	9.22E-3	-7.93
2089-01-19.732	84070.732	-1.346	0.000	0.48 ± 0.149	1.94E7	1.94E-8	9.48E-3	-9.61
2090-01-19.778	84435.778	-1.737	0.000	0.72 ± 0.306	3.10E7	6.48E-9	8.24E-3	-10.15
2091-01-19.840	84800.840	-3.917	0.000	0.14 ± 0.290	9.67E5	4.68E-10	4.44E-3	-11.51
2094-01-19.782	85896.782	-1.609	0.000	1.15 ± 0.161	3.27E6	2.58E-8	8.60E-3	-9.55
2098-01-19.871	87357.871	-1.660	0.000	1.17 ± 0.370	9.57E6	9.19E-9	8.47E-3	-10.03
2100-01-20.210	88088.210	-0.857	0.000	0.71 ± 0.101	2.69E7	2.45E-8	1.16E-2	-9.51
2100-01-20.257	88088.257	-0.855	0.000	1.20 ± 1.526	5.00E6	4.33E-8	1.17E-2	-9.26
2106-01-01.762	90260.762	1.686	1.495	0.89 ± 0.777	7.19E6	5.04E-11	5.18E-2	-11.71
2114-01-19.934	93200.934	-0.258	0.000	1.17 ± 0.365	6.28E5	1.16E-6	1.55E-2	-7.80
2115-01-21.383	93567.383	-0.953	0.000	1.14 ± 0.362	7.37E6	4.01E-8	1.12E-2	-9.38
2115-01-21.493	93567.493	-3.487	0.699	1.25 ± 0.735	2.48E5	3.14E-9	4.94E-3	-10.77


Based on 7 optical observations (of which 0 are rejected as outliers) from 1991/01/18.226 to 1991/01/18.419.
Coordinates are given on the Target Plane.
Unit is one Earth radius, but impact cross section has radius between 1.20 and 1.20 Earth radii.
Coordinates for LOV = EQU scaled= 1 second= F.
AstOD software version= 4.0, Date of computation=20250805 130500.123 UTC.

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