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JPL Small-Body Database Browser
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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 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 36 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1924869425288242 3.9114e-08  
a 3.004002706718768 1.4648e-08 au
q 2.42577141035416 1.1634e-07 au
i 10.69987702125215 4.4741e-06 deg
node 321.1670201885605 2.3096e-05 deg
peri 249.4546243573874 2.5726e-05 deg
M 282.598097764885 1.3625e-05 deg
tp 2459009.382044615575
(2020-Jun-08.88204462)
7.3203e-05 TDB
period 1901.730213483406
5.21
1.3909e-05
3.808e-08
d
yr
n .1893012991262239 1.3846e-09 deg/d
Q 3.582234003083376 1.7467e-08 au
  Orbit Determination Parameters
   # obs. used (total)      2434  
   data-arc span      33330 days (91.25 yr)  
   first obs. used      1928-09-05  
   last obs. used      2019-12-07  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   norm. resid. RMS      .43498  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-Dec-13 20:51:03  

Additional Information
 Earth MOID = 1.44689 au 
 Jupiter MOID = 1.58087 au 
 T_jup = 3.197 
[ 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-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:
[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 00:02 Jupiter 1.65915615830614 1.65915517645394 1.65915714018558 3.08091648196646 2.91050138050297 2429340.657086939 1.67959200951459 394.673381146742 11.033229335806 85.0523484384683 1652389.95824193 T 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
1976-Jun-08 14:47 00:01 Jupiter 1.65176441601846 1.65176371463189 1.65176511741053 0.647652692529839 n/a 2442938.115739410 1.04619432814253 395.00718518349 32.3161171761243 -88.0527300319497 7639748.26563978 F 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
2022-Apr-14 10:51 < 00:01 Jupiter 1.66511921787794 1.6651187337496 1.66511970200903 3.00367564465532 2.82925710408908 2459683.951895605 0.335240228606093 215.506554463086 11.7053038285414 85.1180551174852 2186963.57115761 T 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
2059-Jul-14 17:31 00:01 Jupiter 1.64731867179962 1.64731794949351 1.64731939410753 0.509980088719201 n/a 2473289.230022965 1.44468590881081 212.776115090448 32.8825127908582 -85.9903594401462 7474334.29305464 F 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
2105-May-10 15:33 00:02 Jupiter 1.68346061324162 1.68345941739382 1.68346180912443 2.94299121884969 2.76675080488421 2490025.147580048 2.23232348764798 451.376370423944 12.6824618728516 85.5420790952045 1344529.16598501 T 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
2142-Aug-22 13:54 00:04 Jupiter 1.64997508448525 1.64997385768409 1.64997631128942 0.517868765246896 n/a 2503643.079120809 3.79465165352978 151.099505765323 36.4570766327104 -70.4262337926929 6400715.31595145 F 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51
2188-Jun-06 18:17 00:04 Jupiter 1.68642317116951 1.68642109897829 1.68642524346502 2.8476878032365 2.66548424918334 2520368.261551746 4.22372660808661 728.338183622133 13.7172368632895 86.2437101338465 1101793.83724688 T 36 CATAB v2.0f-lin.ifort 2019-Dec-13 20:51:20 2019-Dec-13 20:51

Alternate Designations
 A921 EM = 1952 DN = 1954 SN1 
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ]
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