Skip Page Navigation
NASA JPL Caltech
NASA Logo - Jet Propulsion Laboratory + View the NASA Portal
+ Center for Near-Earth Object Studies
JPL Home Earth Solar System Stars & Galaxies Technology
JPL Solar System Dynamics
BODIES ORBITS EPHEMERIDES TOOLS PHYSICAL DATA DISCOVERY FAQ SITE MAP
JPL Small-Body Database Browser
Search: [ help ]  
949 Hel (A921 EM)
Classification: Main-belt Asteroid          SPK-ID: 2000949
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]
Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB
Reference: JPL 42 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1922948809866955 3.8794e-08  
a 3.002913051643463 1.1634e-08 au
q 2.425468243764289 1.1576e-07 au
i 10.70138760620475 4.0221e-06 deg
node 321.1674265255299 2.1848e-05 deg
peri 249.5416512626959 2.3871e-05 deg
M 358.2562027325603 9.3877e-06 deg
tp 2459009.706743739666
(2020-Jun-09.20674374)
4.9563e-05 TDB
period 1900.695572912484
5.20
1.1046e-05
3.024e-08
d
yr
n .1894043449832225 1.1007e-09 deg/d
Q 3.580357859522638 1.3871e-08 au
  Orbit Determination Parameters
   # obs. used (total)      2930  
   data-arc span      33630 days (92.07 yr)  
   first obs. used      1928-09-05  
   last obs. used      2020-10-02  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .40347  
   source      ORB  
   producer      Otto Matic  
   solution date      2020-Nov-13 04:24:03  

Additional Information
 Earth MOID = 1.44636 au 
 Jupiter MOID = 1.58163 au 
 T_jup = 3.198 
[ show covariance matrix ]

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 9.8   n/a MPO347521  
diameter diameter 63.494 km 0.743 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2014ApJ...791..121M)  
rotation period rot_per 8.215 h n/a LCDB (Rev. 2019-August); 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:
[Brines, P.; Lozano, J.; Rodrigo, O.; Fornas, A.; et al. (2017) Minor Planet Bull. 44, 145-149.]
geometric albedo albedo 0.058   0.013 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2014ApJ...791..121M)  

949 Hel (A921 EM)          Discovered 1921-Mar-11 by Wolf, M. at Heidelberg
Reference: DISCOVERY.DBLast Updated: 2003-08-29

[ hide close-approach data ]
Close-Approach Data   ...sorted by Date/Time (TDB)
Date/Time (TDB) Time Uncertainty
(days_HH:MM)
Body Nominal Distance (au) Minimum Distance (au) Maximum Distance (au) V-relative (km/s) V-infinity (km/s) JD (TDB) Time Uncertainty (minutes) Semi-major axis (km) Semi-minor axis (km) range-LOV angle (deg) N-sigma BP Orbit Ref. Reference Modified
1939-Mar-18 03:46 00:01 Jupiter 1.65915607592447 1.6591553307313 1.65915682113331 3.08091610755163 2.91050097545618 2429340.657091025 1.3805771442348 309.812354975908 9.53714946951036 85.1698550173396 1836495.61486471 T 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
1976-Jun-08 14:47 < 00:01 Jupiter 1.65176433389735 1.65176374632674 1.65176492146982 0.647653443937411 n/a 2442938.115679928 0.883276578933475 348.256398034707 28.3566772957879 -88.7826574856417 8709529.81210526 F 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
2022-Apr-14 10:51 < 00:01 Jupiter 1.66511912733638 1.66511865992638 1.66511959474979 3.00367517713595 2.82925659797157 2459683.951914657 0.289049235463916 207.569569757095 10.1138176194814 84.7863124402134 2288647.32544485 T 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
2059-Jul-14 17:31 00:01 Jupiter 1.64731859677429 1.64731793663416 1.64731925691563 0.509980470351767 n/a 2473289.229978692 1.17700809401253 189.179787796216 30.4956237212818 -86.1933066442285 8061290.97846738 F 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
2105-May-10 15:33 00:02 Jupiter 1.68346051731133 1.68345944237962 1.68346159227175 2.94299088830481 2.76675044292107 2490025.147593565 1.81537577232498 406.224589166917 10.9568053461822 85.2964412306527 1483081.43222726 T 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
2142-Aug-22 13:54 00:03 Jupiter 1.64997501823324 1.64997394621777 1.64997609025072 0.517868530173315 n/a 2503643.079076832 3.08292749764414 126.983990728513 32.9560757314839 -69.9268967292642 7064185.85559658 F 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24
2188-Jun-06 18:17 00:03 Jupiter 1.68642306680887 1.68642127942614 1.68642485426953 2.84768736366456 2.66548376790309 2520368.261581028 3.43685488439584 631.032885229444 12.1118933302381 86.0540362366649 1206923.85722478 T 42 CATAB v2.0f-lin.ifort 2020-Nov-13 04:24:11 2020-Nov-13 04:24

Alternate Designations
 A921 EM = 1952 DN = 1954 SN1 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
ABOUT SSD CREDITS/AWARDS PRIVACY/COPYRIGHT GLOSSARY LINKS
FirstGov 2020-Nov-30 00:34 UT
(server date/time)  
NASA Home Page
Site Manager:   Ryan S. Park
Webmaster  Alan B. Chamberlin