******************************************************************************* Revised: Apr 03, 2024 134340 Pluto 999 Pre-computed solution PLU060/DE440. Fit to post New Horizons encounter and Gaia data through 2023. For discussion, see ... M. Brozovic, R. A. Jacobson (2024) "Post-New Horizons orbits and masses for the satellites of Pluto". AJ (in press) PHYSICAL DATA (updated 2021-Jun-07; Mc= Charon mass, radius is IAU 2015): Mass x10^22 (kg) = 1.307+-0.018 Volume, 10^10 km^3 = 0.697 GM (planet) km^3/s^2 = 869.326 Density (R=1195 km) = 1.86 g/cm^3 GM 1-sigma, km^3/s^2 = 0.4 Surface gravity = 0.611 m/s^2 Vol. mean radius (km) = 1188.3+-1.6 Mass ratio (Mc/Mp) = 0.122 Sidereal rot. period = 153.29335198 h Sid. rot. rat, rad/s = 0.0000113856 Mean solar day, h = 153.2820 Mean orbit velocity = 4.67 km/s Sidereal orbit period = 249.58932 yr Escape speed, km/s = 1.21 Perihelion Aphelion Mean Solar Constant (W/m^2) 1.56 0.56 0.88 Maximum Planetary IR (W/m^2) 0.8 0.3 0.5 Minimum Planetary IR (W/m^2) 0.8 0.3 0.5 ******************************************************************************* ******************************************************************************* Ephemeris / WWW_USER Wed Jul 8 12:03:54 2026 Pasadena, USA / Horizons ******************************************************************************* Target body name: Pluto (999) {source: plu060_merged} Center body name: Earth (399) {source: DE441} Center-site name: (user defined site below) ******************************************************************************* Start time : A.D. 2026-Aug-27 00:00:00.0000 UT Stop time : A.D. 2026-Oct-31 00:00:00.0000 UT Step-size : 7200 minutes ******************************************************************************* Target pole/equ : {East-longitude positive} Target radii : 1188.3, 1188.3, 1188.3 km {Equator_a, b, pole_c} Center geodetic : 286.833, 42.583, 1.01354E-12 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 286.833, 4703.42262, 4293.50788 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : ITRF93 {East-longitude positive} Center radii : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c} Target primary : Sun Vis. interferer : MOON (R_eq= 1737.400) km {source: DE441} Rel. light bend : Sun {source: plu060_merged} Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian EOP file : eop.260707.p261003 EOP coverage : DATA-BASED 1962-JAN-20 TO 2026-JUL-07. PREDICTS-> 2026-OCT-02 Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO ) Table cut-offs 2: Solar elongation ( 0.0,180.0=NO ),Local Hour Angle( 0.0=NO ) Table cut-offs 3: RA/DEC angular rate ( 0.0=NO ) *************************************************************************************************************************************************************** Date__(UT)__HR:MN R.A._____(ICRF)_____DEC Azi____(a-app)___Elev a-mass mag_ex APmag S-brt delta deldot Cnst Lun_Sky_Brt sky_SNR *************************************************************************************************************************************************************** $$SOE 2026-Aug-27 00:00 Cm 20 26 25.83 -23 36 41.4 138.546698 11.999487 4.682 1.316 14.492 9.105 34.7110151847242 16.0128373 Cap n.a. n.a. 2026-Sep-01 00:00 N 20 26 02.00 -23 38 05.8 142.631298 14.329376 3.965 1.115 14.501 9.110 34.7609790879521 18.1483460 Cap n.a. n.a. 2026-Sep-06 00:00 N 20 25 39.92 -23 39 21.5 146.870557 16.444099 3.483 0.979 14.509 9.115 34.8169495481573 20.1909700 Cap n.a. n.a. 2026-Sep-11 00:00 N 20 25 19.82 -23 40 27.8 151.262462 18.324306 3.145 0.884 14.517 9.119 34.8785710645955 22.1196790 Cap n.a. n.a. 2026-Sep-16 00:00 Nm 20 25 01.92 -23 41 24.1 155.799502 19.951632 2.903 0.816 14.525 9.123 34.9454099262824 23.8772887 Cap n.a. n.a. 2026-Sep-21 00:00 Am 20 24 46.38 -23 42 10.2 160.468246 21.308758 2.730 0.767 14.533 9.127 35.0169777114680 25.4372957 Cap 2.516 3.628 2026-Sep-26 00:00 Am 20 24 33.36 -23 42 46.1 165.249212 22.380368 2.607 0.733 14.541 9.130 35.0927614304142 26.8163457 Cap 2.869 3.182 2026-Oct-01 00:00 A 20 24 23.01 -23 43 11.5 170.117055 23.154354 2.526 0.710 14.549 9.132 35.1722323823334 28.0373320 Cap n.a. n.a. 2026-Oct-06 00:00 A 20 24 15.43 -23 43 26.2 175.041530 23.621972 2.480 0.697 14.556 9.135 35.2548598958272 29.0822775 Cap n.a. n.a. 2026-Oct-11 00:00 20 24 10.73 -23 43 30.1 179.989065 23.778715 2.465 0.693 14.563 9.137 35.3400801195079 29.9013406 Cap n.a. n.a. 2026-Oct-16 00:00 m 20 24 08.99 -23 43 23.4 184.924441 23.624718 2.479 0.697 14.570 9.138 35.4272720673319 30.4790905 Cap 0.379 24.107 2026-Oct-21 00:00 m 20 24 10.27 -23 43 06.3 189.813065 23.164338 2.525 0.710 14.576 9.139 35.5157825290141 30.8414615 Cap 2.389 3.826 2026-Oct-26 00:00 m 20 24 14.59 -23 42 38.8 194.623113 22.406405 2.605 0.732 14.582 9.139 35.6049594705114 31.0062440 Cap 2.738 3.338 2026-Oct-31 00:00 20 24 21.92 -23 42 01.3 199.327006 21.363465 2.723 0.766 14.587 9.139 35.6941898717860 30.9629211 Cap n.a. n.a. $$EOE *************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. SOLAR PRESENCE (OBSERVING SITE) Time tag is followed by a blank, then a solar-presence symbol: '*' Daylight (refracted solar upper-limb on or above apparent horizon) 'C' Civil twilight/dawn 'N' Nautical twilight/dawn 'A' Astronomical twilight/dawn ' ' Night OR geocentric ephemeris LUNAR PRESENCE (OBSERVING SITE) The solar-presence symbol is immediately followed by a lunar-presence symbol: 'm' Refracted upper-limb of Moon on or above apparent horizon ' ' Refracted upper-limb of Moon below apparent horizon OR geocentric ephemeris 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'a-mass mag_ex' = RELATIVE optical airmass and visual magnitude extinction. Airmass is the ratio between the absolute optical airmass for the targets' refracted CENTER point to the absolute optical airmass at zenith. Also output is the estimated visual magnitude extinction due to the atmosphere, as seen by the observer. AVAILABLE ONLY FOR TOPOCENTRIC EARTH SITES WHEN THE TARGET IS ABOVE THE HORIZON. Units: none (airmass) and magnitudes (extinction). 'APmag S-brt' = Pluto's approximate apparent visual magnitude and surface brightness. The computed value includes Charon. Values are available only for solar phase angles in the range generally visible from Earth. If that occurs, "n.a." is output. This is to avoid error due to extrapolation of the model beyond its valid data-based limit. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S 'Cnst' = Constellation ID; the 3-letter abbreviation for the name of the constellation containing the target centers' astrometric position, as defined by IAU (1930) boundary delineation. See documentation for list of abbreviations. 'Lun_Sky_Brt sky_SNR' = Sky brightness due to moonlight scattered by Earth's atmosphere at the target's position in the sky. "sky_SNR" is the visual signal-to-noise ratio (SNR) of the target's surface brightness relative to background sky. Output only for topocentric Earth observers when both the Moon and target are above the local horizon and the Sun is in astronomical twilight (or further) below the horizon, and the target is not the Moon or Sun. If all conditions are not met, "n.a." is output. Galactic brightness, local sky light-pollution and weather are NOT considered. Lunar opposition surge is considered. The value returned is accurate under ideal conditions at the approximately 8-23% level, so is a useful but not definitive value. If the target-body radius is also known, "sky_SNR" is output. This is the approximate visual signal-to-noise ratio of the target's brightness divided by lunar sky brightness. When sky_SNR < 1, the target is dimmer than the ideal moonlight-scattering background sky, so unlikely to be detectable at visual wavelengths. In practice, visibility requires sky_SNR > 1 and a detector sensitive enough to reach the target's magnitude, even if it isn't washed out by moonlight. When relating magnitudes and brightness values, keep in mind their logarithmic relationship m2-m1 = -2.5*log_10(b2/b1). UNITS: VISUAL MAGNITUDES / ARCSECOND^2, and unitless ratio Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Inquiries : Jon.D.Giorgini@jpl.nasa.gov ***************************************************************************************************************************************************************