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177 Irma (A877 VA)
Classification: Main-belt Asteroid          SPK-ID: 2000177
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

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For accurate long-term ephemerides, please instead use our Horizons system.This orbit viewer was implemented using two-body methods, and hence should not be used for determining accurate long-term trajectories (over several years or decades) or planetary encounter circumstances.

Orbital Elements at Epoch 2459200.5 (2020-Dec-17.0) TDB
Reference: JPL 96 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .2337277242766262 1.6751e-08  
a 2.771168817844914 6.4203e-09 au
q 2.123469836463674 4.6818e-08 au
i 1.382268098407373 7.4408e-07 deg
node 346.9768619393315 3.3557e-05 deg
peri 39.38110702273765 3.5048e-05 deg
M 23.06992086582308 3.1683e-06 deg
tp 2459092.521694899545
1.4732e-05 TDB
period 1684.97282943658
n .2136532967836499 7.425e-10 deg/d
Q 3.418867799226155 7.9209e-09 au
  Orbit Determination Parameters
   # obs. used (total)      3404  
   data-arc span      43982 days (120.42 yr)  
   first obs. used      1900-10-23  
   last obs. used      2021-03-24  
   planetary ephem.      DE441  
   SB-pert. ephem.      SB441-N16  
   condition code      0  
   norm. resid. RMS      .4455  
   source      ORB  
   producer      Otto Matic  
   solution date      2021-May-03 17:59:19  

Additional Information
 Earth MOID = 1.1268 au 
 Jupiter MOID = 2.04096 au 
 T_jup = 3.296 
[ show covariance matrix ]

Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 9.68   n/a E2021B10 IRAS observations used: 12
diameter diameter 69.049 km 0.649 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (  
rotation period rot_per 13.856 h n/a LCDB (Rev. 2020-October); Warner et al., 2009 Published Reference List:
[Wetterer, C.J.; Saffo, C.R.; Majcen, S.; Tompkins, J. (1999) Minor Planet Bull. 26, 30-31.]
[Pilcher, F. (2012) Minor Planet Bull. 39, 57-60.]
[Pilcher, F. (2013) Minor Planet Bull. 40, 161-163.]
[Behrend, R. (2020) Observatoire de Geneve web site,]
geometric albedo albedo 0.022   0.007 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (  
B-V BV 0.730   0.030 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=2; phase (min.=6.23, mean=6.27, max.=6.30) deg.
U-B UB 0.350   0.040 EAR-A-5-DDR-UBV-MEAN-VALUES-V1.2 #obs=2; phase (min.=6.23, mean=6.27, max.=6.30) deg.
Tholen spectral type spec_T C:   n/a EAR-A-5-DDR-TAXONOMY-V4.0 used 2 color indices
SMASSII spectral type spec_B Ch   n/a EAR-A-5-DDR-TAXONOMY-V4.0 based on a high-resolution spectrum by Xu et al. (1995) or Bus and Binzel (2002)

177 Irma (A877 VA)          Discovered 1877-Nov-05 by Henry, Paul at Paris
In their cooperative program it will probably never be known which of the Henry brothers discovered which planet. With strict impartiality, these discoveries were announced as having been made alternatively by Prosper and by Paul.
Note: "planet" implies "minor planet"
Reference: DISCOVERY.DBLast Updated: 2003-08-29

Alternate Designations
 A877 VA = 1937 UA = 1962 DB = A900 UB = A900 VA = A912 HE 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances ]
FirstGov 2021-Jun-17 00:59 UT
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