J/A+A/650/A64ivo://CDS.VizieR/J/A+A/650/A64doi:10.26093/cds/vizier.36500064CDSLainey V.Pasewaldt A.Robert V.Rosenblatt P.Jaumann R.Oberst J.,Roatsch T.Willner K.Ziese R.Thuillot W.2022-03-17T14:12:25Z2021-12-20T08:11:39ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsolar-systemsolar-system-planetsephemeridesThe Mars Express (MEX) mission has been successfully operated around Mars since 2004. Among many results, MEX has provided some of the most accurate astrometric data of the two Mars moons, Phobos and Deimos. We present new ephemerides of the Mars moons benefitting from all previously published astrometric data to the most recent MEX SRC data. Observations from 1877 until 2018 and including spacecraft measurements from Mariner 9 to MEX were included. Assuming a homogeneous interior, we fitted the forced libration amplitude of Phobos simultaneously with the Martian tidal k2/Q ratio and the initial state of the moons. Our solution of the physical libration 1.09+/-0.01 degrees deviates notably from the homogeneous solution. Considering the very low error bar, however, this may essentially suggest the necessity to consider higher order harmonics with an improved rotation model in the future. While most data could be successfully fitted, we found a disagreement between the Mars Reconnaissance Orbiter and the Mars Express astrometric data at the kilometer level, probably associated with a biased phase correction. The current solution precision is expected at the level of a few hundred meters for Phobos and several hundred meters for Deimos for the coming years. The real accuracy of our new ephemerides will have to be confirmed by comparison with independent observational means.2021A&A...650A..64Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/650/A64CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/488/361 : Phobos Mars Express astrometric observations (Willner+, 2008)J/A+A/545/A144 : Astrometric observations of Deimos (Pasewaldt+, 2012)J/A+A/572/A104 : Astrometric obs. of Phobos and Deimos in 1971 (Robert+, 2014)J/A+A/580/A28 : Astrometric observations of Phobos (Pasewaldt+, 2015)J/A+A/582/A36 : USNO Martian observations (Robert+, 2015)J/A+A/614/A15 : Mars Express astrometric obs. of Martian moons (Ziese+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/650/A64https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/650/A64http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/650/A64https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/650/A64https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/650/A64http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/650/A64GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/650/A64/table2Mean and standard deviation on separation and position anglerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsObservations (1)meta.code;obscharSep[] Mean separationarcsecpos.angDistance;src.orbitalfloats_SepStandard deviation on separationarcsecstat.stdev;pos.angDistancefloatPA[] Mean position angle (multiplied by the separation)arcsecpos.posAng;stat.meanfloats_PAStandard deviation on position anglearcsecstat.stdev;pos.posAngfloato_SepNumber of observations by satellite for separationmeta.numberinto_PANumber of observations by satellite for position anglemeta.numberintSatSatellite, Phobos or Deimosmeta.id;meta.maincharJ/A+A/650/A64/table3Mean and standard deviation on right ascension and declination for each satelliterecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsObservationsmeta.code;obscharRAcosDEMean right ascension, RA*cosDEarcsecpos.eq.ra;stat.means_RAcosDEStandard deviation on right ascension (RA*cosDE)arcsecstat.stdev;pos.eq.rafloatDEMean declinationarcsecpos.eq.dec;arith.diffs_DEStandard deviation on declinationarcsecstat.stdev;pos.eq.decfloato_RAcosDENumber of observations by satellite for RAcosDEmeta.numberinto_DENumber of observations by satellite for DEmeta.numberintSatSatellite, Phobos or Deimosmeta.id;meta.maincharJ/A+A/650/A64/table4*Mean and standard deviation on right ascension and declination for each satelliterecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsObservationsmeta.code;obscharRAcosDEMean right ascension, RA*cosDEarcsecpos.eq.ra;stat.means_RAcosDEStandard deviation on right ascension (RA*cosDE)arcsecstat.stdev;pos.eq.rafloatDEMean declinationarcsecpos.eq.dec;arith.diffs_DEStandard deviation on declinationarcsecstat.stdev;pos.eq.decfloato_RAcosDENumber of observations by satellite for RAcosDEmeta.numberinto_DENumber of observations by satellite for DEmeta.numberintSatSatellite, Phobos or Deimosmeta.id;meta.maincharJ/A+A/650/A64/table5Mean and standard deviation on and line in pixel and kilometer for each satelliterecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsObservations (1)meta.code;obscharsamplepMean on sample in pixelpixphys.size.diameterfloatsamplekMean on sample in kilometerkmphys.size.diameterfloats_samplepStandard deviation on sample in pixelpixstat.stdev;src.sample;instr.pixelfloats_samplekStandard deviation on sample in kilometerkmstat.stdev;src.samplefloatlinepMean line in pixelpixphys.size.diameterfloatlinekMean line in kilometerkmphys.size.diameterfloats_linepStandard deviation on line in pixelpixstat.errorfloats_linekStandard deviation on line in kilometerkmstat.stdev;spect.linefloato_sampleNumber of observation for samplemeta.numberinto_lineNumber of observation for linemeta.numberintSatSatellite, Phobos or Deimosmeta.id;meta.maincharJ/A+A/650/A64/table6*Initial conditions and related uncertainties of Phobos and Deimos in the ICRF after fit at initial epoch J2000 (Julian day 2451545.0)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSatSatellite, Phobos or Deimosmeta.id;meta.maincharxX positionkmpos.cartesian.xdoublee_xError on X positionkmstat.error;pos.cartesian.xfloatyY positionkmpos.cartesian.ydoublee_yError on Y positionkmstat.error;pos.cartesian.yfloatzZ positionkmsrc.redshiftdoublee_zError on Z positionkmstat.error;src.redshiftfloatvxVelocity along X axiskm/sphys.velocdoublee_vxError on velocity along X axiskm/sstat.errordoublevyVelocity along Y axiskm/sphys.velocdoublee_vyError on velocity along Y axiskm/sstat.errordoublevzVelocity along Z axiskm/sphys.velocdoublee_vzError on velocity along Z axiskm/sstat.errordouble