KPL/PCK \begin text Asteroid 162173 Ryugu PCK File =========================================================================== Release note -------------------------------------------------------- Version 20190328 -- Mar 28, 2019 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20190308 -- Mar 08, 2019 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20181109 -- Nov 09, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20181014 -- Oct 14, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180805 -- Aug 10, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180805 -- Aug 05, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180731 -- July 31, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180727 -- July 27, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180717 -- July 17, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180710 -- July 10, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180705 -- July 05, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata (Kobe Univ.) with SPC. PM/W0 is adjusted to the official definition of Hayabusa2 project. Version 20180630 -- June 30, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata with SPC. PM/W0 is arbitrary adjusted to ONC images. Version 20180627 -- June 27, 2018 -- N.Hirata Pole information estimated by Naoyuki Hirata with SPC. PM/W0 is arbitrary adjusted to ONC images. Version 0.5 -- May 24, 2018 -- Y.Yamamoto Fix asteroid parameters according to Mueller et al. (2017) Version 0.4 -- April 5, 2018 -- Y.Ishihara and Y.Yamamoto Update asteroid parameters according to Mueller et al. (2017) Version 0.3 -- March 29, 2018 -- Shin-ya Murakami Update with some cosmetic changes Version 0.2 -- May 18, 2017 -- Y.Ishihara and Y.Yamamoto Split the FK and PCK contents into two kernels respectively Version 0.1 -- June 16, 2016 -- Manabu YAMADA PERC/Chitech Added the Ryugu name-ID mapping Version 0.0 -- June 16, 2016 -- Y.Ishihara and Y.Yamamoto Draft version by ground observation (As of Sep.22,2014) Parameter History -------------------------------------------------------- Date RA [deg] DEC [deg] Period [h] Init.Rot.Angle(JD0) ---------- ----------- ---------- ---------- ------------------------- 2019-03-28 96.43112 -66.38741 7.632624787382541 2019-03-08 96.42997 -66.39277 7.6326238293793 2018-11-09 96.40503 -66.38442 7.632616576126643 2018-10-14 96.40101 -66.39948 7.632621866444357 2018-08-29 96.39792 -66.39867 7.632622910551389 2018-08-10 96.39069 -66.40321 7.632625803575571 2018-08-05 96.38837 -66.40425 7.632626749577289 2018-07-31 96.37915 -66.41831 7.632613738534321 2018-07-27 96.35333 -66.42016 7.632595559221877 2018-07-17 96.36813 -66.40245 7.63255 2018-07-10 96.34221 -66.42105 7.63253 2018-07-05 96.33551 -66.47482 7.63249 2018-06-30 96.17157 -66.53653 7.63253 2018-06-27 95.783988 -66.382491 7.63109 in J2000EQ Date Lambda[deg] Beta[deg] Period [h] Init.Rot.Angle(JD0) ---------- ----------- ---------- ---------- ------------------------- 2018-04-05 310.0-340.0 -40.0+-15 7.63109 2016-03-04 329.0+-10 -39.0+-20 7.6312 phi0=0 JD0=2454289.000000 2014-09-22 325.0+-10 -40.0+-15 7.6312 2014-09-19 326.478506 -36.065302 7.63121164 phi0=0 JD0=2454289.000000 As of March 09, 2017, Rotational period 7.63109 hr [2] H0 in V-band 19.22 +- 0.02 [1] G parameter (a<30 deg) 0.13 +- 0.02 [1] Geometric albedo 0.047 +- 0.003 [1] Effective diameter 850 - 880 m [2] Thermal inertia 150 - 300 JmSUP{-2};sSUP{-0.5};KSUP{-1}; [2] Pole orientation (l,b) = (340,-40) deg (Table 5, ID 2) [2] Heat conductivity 0.1 to 0.6 W;KSUP{-1};mSUP{-1} [2] Grain size 1 - 10 mm [2] Axis ratios (a/b,b/c) = (1.025, 1.014) [2] As of March 4, 2016, From design reference: Rotational period 7.6312 hr G parameter (a<30 deg) 0.13 +- 0.02 Geometric albedo 0.047 +- 0.043-0.050 (V-band) Effective diameter 880 +- 15 m Thermal inertia 250 +- 150-500 JmSUP{-2};sSUP{-0.5};KSUP{-1}; Pole orientation (l,b) = (329,-39) +- (10, 20) deg Surface slope 0.1 rms GM 32 mSUP{3};sSUP{-2} Ellipsoidal shape a=446.5,b=439.7,c=433.9 m Axis ratios (a/b,b/c) = (1.0153, 1.0135) As of September 22,2014 From private communication with Thomas Mueller: Rotational period 7.6312 +- 0.0010 hr H0 in V-band 19.25 +- 0.03 G parameter (a<30 deg) 0.3 +- 0.02 Geometric albedo 0.047 +- 0.003 Effective diameter 875 +- 15 m Thermal inertia 50 +- 50 JmSUP{-2};sSUP{-0.5};KSUP{-1}; Pole orientation (l,b) = (325,-40) +- (10, 15) deg l ... lambda_ecl (Ecliptic longitude) b ... beta_ecl (Ecliptic latitude) Reference -------------------------------------------------------- [1] Ishiguro, et al (2014), Optical Properties of (162173) 1999 JU3: In Preparation for the JAXA Hayabusa 2 Sample Return Mission, ApJ, 792, 74. http://dx.doi.org/10.1088/0004-637X/792/1/74 [2] Mueller, et al (2017), Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object's spin-axis orientation, A&A, 599, A103. https://doi.org/10.1051/0004-6361/201629134 -------------------------------------------------------- Ecliptic longitude and latitude are converted from the following source code. #include #include int main() { SpiceDouble lambda = 340.0 * rpd_c(); SpiceDouble beta = -40.0 * rpd_c(); SpiceDouble pole_ecliptic[3]; SpiceDouble pole[3]; SpiceDouble ra, dec, d; SpiceDouble tx[3][3]; radrec_c( 1.0, lambda, beta, pole_ecliptic ); pxform_c( "eclipj2000", "j2000", 0, tx ); mxv_c( tx, pole_ecliptic, pole ); recrad_c( pole, &d, &ra, &dec ); printf( "(ra,dec)=(%.7f %.7f)\n", ra * dpr_c(), dec * dpr_c() ); return 0; } The prime meridian (PM) is not determined yet, therefore, we assumed pm (W0) is 0.0. The W1 term was set to correspond to the period of 7.6312 +/- 0.0010 hours. 1 [rev] W1 = -------------- x 360 [deg/rev] x 24 [hours/day] 7.63109 [hours] = 1132.210471 [deg/day] \begindata BODY2162173_POLE_RA = ( 96.43112 0.0 0.0 ) BODY2162173_POLE_DEC = ( -66.38741 0.0 0.0 ) BODY2162173_PM = ( 274.16225 1131.98280286 0.0 ) \begintext Radii for Asteroid Ryugu -------------------------------------------------------- The radii provided in the keyword below are also from [2]. \begindata BODY2162173_RADII = ( 0.4325 0.4325 0.4325 ) \begintext Albedo Values for Asteroid Ryugu -------------------------------------------------------- The albedo provided in the keywords below is taken from the reference. \begindata BODY2162173_ALBEDO_GEOMETRIC = 0.047 \begintext RYUGU name-ID mappings -------------------------------------------------------- The keywords below implement the RYUGU name-ID mappings. \begindata NAIF_BODY_NAME += ( 'RYUGU' ) NAIF_BODY_CODE += ( 2162173 ) NAIF_BODY_NAME += ( '1999JU3' ) NAIF_BODY_CODE += ( 2162173 ) \begintext End of PCK file.