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JPL Small-Body Database Browser
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21795 Masi (1999 SN9)
Classification: Main-belt Asteroid          SPK-ID: 2021795
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

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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.

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Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 18 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1927866701894724 3.1765e-08  
a 2.381052897968518 8.9411e-09 au
q 1.922017638224174 7.5178e-08 au
i 1.837756503284501 5.1966e-06 deg
node 337.0803295104127 0.00011604 deg
peri 81.62568934387508 0.00011689 deg
M 84.69054642937424 1.4875e-05 deg
tp 2458284.792843318141
5.4623e-05 TDB
period 1341.9983834943
n .2682566569585804 1.511e-09 deg/d
Q 2.840088157712862 1.0665e-08 au
  Orbit Determination Parameters
   # obs. used (total)      1302  
   data-arc span      24125 days (66.05 yr)  
   first obs. used      1953-04-15  
   last obs. used      2019-05-04  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .52237  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-May-30 03:02:14  

Additional Information
 Earth MOID = .935006 au 
 Jupiter MOID = 2.50083 au 
 T_jup = 3.512 
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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 14.9   n/a MPO337442  
diameter diameter 3.150 km 0.164 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (  
rotation period rot_per 13.862 h n/a LCDB (Rev. 2019-January); Warner et al., 2009 Result based on less than full coverage, so that the period may be wrong by 30 percent or so.
Published Reference List:
[Waszczak, A.; Chang, C.-K.; Ofeck, E.O.; Laher, F.; et al. (2015) Astron. J. 150, A75.]
geometric albedo albedo 0.235   0.037 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (  

21795 Masi           Discovered 1999 Sept. 29 by F. Mallia at Campo Catino.
Gianluca Masi (b. 1972), an amateur astronomer since 1980, is involved with several scientific projects, mainly on cataclysmic variable stars and minor planets. He has discovered a variable star and several minor planets. He collaborates with several institutions through several observing programs.
NOTE: some special characters may not display properly (any characters within {} are an attempt to place the proper accent above a character)
Reference: 20010509/MPCPages.arcLast Updated: 2009-05-11

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Alternate Designations
 1999 SN9 = 1988 UE = 1993 BZ1 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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