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991 McDonalda (A922 UC)
Classification: Main-belt Asteroid          SPK-ID: 2000991
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]
Orbital Elements at Epoch 2459396.5 (2021-Jul-01.0) TDB
Reference: JPL 46 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1594062534300184 2.9864e-08  
a 3.13936081375573 1.1976e-08 au
q 2.638927068269915 9.8198e-08 au
i 2.069528447347803 3.2479e-06 deg
node 63.2343423417676 9.0545e-05 deg
peri 254.7832608288123 9.1128e-05 deg
M 309.2977614887167 1.1574e-05 deg
tp 2459682.644175048139
(2022-Apr-13.14417505)
6.5965e-05 TDB
period 2031.703254963895
5.56
1.1626e-05
3.183e-08
d
yr
n .1771912306191573 1.0139e-09 deg/d
Q 3.639794559241545 1.3885e-08 au
  Orbit Determination Parameters
   # obs. used (total)      3616  
   data-arc span      31177 days (85.36 yr)  
   first obs. used      1936-02-20  
   last obs. used      2021-06-30  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .42965  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Jul-08 11:49:13  

Additional Information
 Earth MOID = 1.626 au 
 Jupiter MOID = 1.66413 au 
 T_jup = 3.190 
[ hide covariance matrix ]
Orbital Elements at Epoch 2456858.5 (2014-Jul-20.0) TDB
Reference: JPL 46 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1572565859058231 2.984e-08  
q 2.647691477234484 9.7942e-08 au
tp 2457649.098073740686
(2016-Sep-17.59807374)
6.3023e-05 TDB
node 63.26441639448478 9.0495e-05 deg
peri 254.6844920856991 9.1097e-05 deg
i 2.069659268684171 3.247e-06 deg
  Orbit Determination Parameters
   # obs. used (total)      3616  
   data-arc span      31177 days (85.36 yr)  
   first obs. used      1936-02-20  
   last obs. used      2021-06-30  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .42965  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-Jul-08 11:49:13  

Additional Information
 Jupiter MOID = 1.66413 au 
 T_jup = 3.190 
Orbit Covariance (6×6)
  e q tp node peri i
e 8.904010222555311E-16 -2.909251621949826E-15 -3.755951470520905E-14 4.44781890169872E-15 1.585547077996011E-14 -1.036383027823582E-16
q -2.909251621949826E-15 9.592546258036553E-15 2.638028484353849E-13 -2.00087258297965E-14 -3.062450661674455E-14 5.354943356806818E-16
tp -3.755951470520905E-14 2.638028484353849E-13 3.971902804153053E-9 7.236196741364381E-12 6.706800715106548E-10 1.920450679447028E-13
node 4.44781890169872E-15 -2.00087258297965E-14 7.236196741364381E-12 8.189254594395297E-9 -8.182549686161564E-9 -4.839229904965259E-11
peri 1.585547077996011E-14 -3.062450661674455E-14 6.706800715106548E-10 -8.182549686161564E-9 8.298717057142035E-9 4.839517158968974E-11
i -1.036383027823582E-16 5.354943356806818E-16 1.920450679447028E-13 -4.839229904965259E-11 4.839517158968974E-11 1.054315582852619E-11

Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 11.26   n/a E2021B10 IRAS observations used: 15
diameter diameter 38.556 km 0.514 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  
geometric albedo albedo 0.040   0.005 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)  
B-V BV 0.660   0.020 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=1; phase=11.11 deg.
U-B UB 0.370   0.045 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=1; phase=11.11 deg.
Tholen spectral type spec_T C:   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 2 color indices

991 McDonalda (A922 UC)          Discovered 1922-Oct-24 by Struve, O. at Williams Bay
Reference: DISCOVERY.DBLast Updated: 2003-08-29

[ show close-approach data ]
Alternate Designations
 A922 UC = 1949 PF = 1950 WG = 1953 GT1 = 1975 EE6 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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