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2154 Underhill (2015 P-L)
Classification: Main-belt Asteroid          SPK-ID: 2002154
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances ]

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Orbit Diagram
Note: Make sure you have Java enabled on your browser to see the applet. This applet is provided as a 3D orbit visualization tool. The applet was implemented using 2-body methods, and hence should not be used for determining accurate long-term trajectories (over several years or decades) or planetary encounter circumstances. For accurate long-term ephemerides, please instead use our Horizons system.

Note: If the applet has stopped working because of a recent Java upgrade, here is a possible workaround.
Orbit Viewer

Additional Notes: the orbits shown in the applet are color coded. The planets are white lines, and the asteroid/comet is a blue line. The bright white line indicates the portion of the orbit that is above the ecliptic plane, and the darker portion is below the ecliptic plane. Likewise for the asteroid/comet orbit, the light blue indicates the portion above the ecliptic plane, and the dark blue the portion below the ecliptic plane.

Orbit Viewer applet originally written and kindly provided by Osamu Ajiki (AstroArts), and further modified by Ron Baalke (JPL).

Orbital Elements at Epoch 2457600.5 (2016-Jul-31.0) TDB
Reference: JPL 14 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1228266386843605 5.2791e-08  
a 2.636676475696962 1.5911e-08 au
q 2.312822366888978 1.39e-07 au
i 7.746077821155112 6.632e-06 deg
node .8725329760514307 3.8516e-05 deg
peri 119.9633334132196 4.5453e-05 deg
M 282.5807435572121 2.5968e-05 deg
tp 2457936.802571952324
0.00011393 JED
period 1563.808947097101
n .2302071494527949 2.0837e-09 deg/d
Q 2.960530584504947 1.7865e-08 au
  Orbit Determination Parameters
   # obs. used (total)      1106  
   data-arc span      21046 days (57.62 yr)  
   first obs. used      1958-04-08  
   last obs. used      2015-11-21  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-BIG16  
   condition code      0  
   fit RMS      .47885  
   data source      ORB  
   producer      Otto Matic  
   solution date      2015-Nov-30 15:37:20  

Additional Information
 Earth MOID = 1.33826 au 
 Jupiter MOID = 2.12039 au 
 T_jup = 3.373 
[ show covariance matrix ]

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

Physical Parameter Table
Parameter Symbol Value Units Sigma Reference Notes
absolute magnitude H 12.9 mag n/a MPO259351  

2154 Underhill (2015 P-L)          Discovered 1960-Sep-24 by PLS at Palomar
These planets have all been discovered as a result of the Palomar survey of faint minor planets and subsequently identified with planets observed at other oppositions. In Sept. and Oct. 1960, T. Gehrels exposed 130 plates with the 122 cm Schmidt camera at Palomar. In the following years C. J. van Houten and I. van Houten-Groeneveld measured these plates astrometrically and photometrically at Leiden. P. Herget, Cincinnati, computed the orbits of the planets found on the NORC computer, Dahlgren, Virginia, USA.
Note: "planet" implies "minor planet"
Reference: DISCOVERY.DBLast Updated: 2003-08-29

Alternate Designations
 2015 P-L = 1958 GU = 1973 SN4 = 1973 UC4 = 1979 DB 
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances ]
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