+ View the NASA Portal + Center for Near-Earth Object Studies JPL Small-Body Database Browser Search: [ help ]   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 ] [ show orbit diagram ] Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB Reference: JPL 18 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1923606826999376 3.1732e-08   a 2.381664361704629 8.8883e-09 au q 1.923525779125015 7.5068e-08 au i 1.837643554839744 5.1964e-06 deg node 337.0689869681251 0.00011603 deg peri 81.60563729263221 0.00011689 deg M 192.0427320685734 1.5218e-05 deg tp 2459626.847812274405 (2022-Feb-16.34781227) 5.8672e-05 TDB period 1342.515362364947 3.68 7.5153e-06 2.058e-08 d yr n .2681533560746981 1.5011e-09 deg/d Q 2.839802944284242 1.0598e-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 = .936877 au   Jupiter MOID = 2.50142 au   T_jup = 3.512  [ 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 14.9   n/a MPO337442   diameter diameter 3.150 km 0.164 urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   rotation period rot_per 13.862 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: [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] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)   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.arc Last Updated: 2009-05-11 [ show close-approach data ] Alternate Designations  1999 SN9 = 1988 UE = 1993 BZ1  [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Discovery Circumstances | Close-Approach Data ] 2020-Jul-02 13:49 UT (server date/time)   Site Manager:   Ryan S. Park Webmaster:   Alan B. Chamberlin