Summary for : (498) Tokio

DynT.TT.BT T.L B T.DDensity (g/cm^3)Δρ/ρDiameter (km)ΔD/DMass (kg)ΔM/MRefAvg.M
MBAM-- | --3.42 ± 2.10   (D)61 %70.1 ± 8.812.6 %6.16e+17 ± 2.98e+1748 %SEVM
MBAM-- | --3.63 ± 2.23   (D)61 %68.7 ± 8.612.6 %6.16e+17 ± 2.98e+1748 %Sw.avg

Average asteroid densities (g/cm^3):
C = 1.3 ± 0.6, B = 2.4 ± 0.5, S = 2.7 ± 0.5, M = 3.5 ± 1.0, P = 2.8 ± 1.6, X = 1.9 ± 0.8, Xc = 4.9 ± 0.9, Xk = 4.2 ± 0.7 (Ref)

Additional resources:
3D Model | JPL New Horizons | Minor Planet Center | Wikipedia (these auto-generated links might not work)

Note: The density estimates have been ranked from (A) to (E), corresponding to the relative error: (B) less than 20%, (C) between 20 and 50%, (D) between 50 and 100%, and (E) more than 100%. (A) stands for (presumably) reliable estimates (accuracy better than 20%), based on more than 5 mass estimates and 5 diameter estimates, or a spacecraft encounter. Apparently unrealistic densities (ρ > 8) are tagged with (X).

EVM: average by using the Expected Value Method (Ref). w.avg: weighted average (with w = 1/err^2).

T.T: Tholen Tax Class. T.B: Bus & Binzel Tax Class. T T.L: S3OS2 Lazarro (Tholen) Tax Class. T.L B: S3OS2 Lazarro (Bus & Binzel) Tax Class. T.D: DeMeo Tax Class.

Ref: S = SiMDA, C = Carry (2012)

Diameter estimates

DesignationDiameter / Err (km)ΔD/DMethodYearRefNχ2Use
(498) Tokio79.16 ± 3.544.5 % STM2010D64 6.57 1
(498) Tokio62.36 ± 0.030.0 % STM2010D642 66315.53 2
(498) Tokio90.90 ± 4.184.6 % NEATM2010D64 24.80 3
(498) Tokio79.97 ± 0.040.1 % NEATM2010D642 61064.08 4

plot, average diameter and derived density

All

Notes (N):
1: This estimate is discarded for the average diameter (and derived density) calculation in Carry (2012).
2: This estimate is discarded for the average diameter (and derived density) calculation in SiMDA (catalog).

NEATM : Near-Earth Asteroid Thermal Model. STM : Standard Thermal Model.


EVM diam. average D = (70.1 ± 8.81) km   (ΔD/D = 13%, SNR = 7.96) Derived bulk density ρ = (3.42 ± 2.10) g/cm3   (Δρ/ρ = 61%, SNR = 1.6)


References
D64(2010):Ryan, E.L., Woodward, C.E., 2010. Rectified Asteroid Albedos and Diameters from IRAS and MSX Photometry Catalogs. Astronomical Journal 140, 933–943.

Mass estimates

DesignationMass / Err (kg)ΔM/MMethodYearRefNχ2Use
(498) Tokio6.16e+17 ± 2.98e+1748 %Ephem 2019M1260.00 1

Notes (N):
1: This estimate is discarded for the average mass (and derived density) calculation in Carry (2012).
2: This estimate is discarded for the average mass (and derived density) calculation in SiMDA (catalog).
3: This estimate is an average of individual solutions listed before under the same reference (e.g. M125).

Ephem : Planetary ephemeris solution.


EVM mass average M = (6.163 ± 2.980) × 1017 kg   (ΔM/M = 48%, SNR = 2.1) Derived bulk density ρ = (3.42 ± 2.10) g/cm3   (Δρ/ρ = 61%, SNR = 1.6)


References
M126(2019):Fienga, A., et. al, 2019. INPOP19a planetary ephemeris. Notes Scientifiques et Techniques de l'Institut de mécanique céleste,