urn:nasa:pds:jpl.dsn.mmm:eop:2025_186_2026_187_eop 1.0 1.16.0.0 Product_Observational Kahan, Daniel 2026 Earth Orientation Parameter file for radio science and other observations. Produced by the JPL Time and Earth Motion Precision Observation (TEMPO) Group. 2026-04-09 1.0 Initial version created from original file latest.short downloaded from http://eop.jpl.nasa.gov or recovered from a file previously archived for 2001 Mars Odyssey and/or Mars Express radio science under PDS3 standards. Trailing blank records in an original file, if any, have been deleted. Data file names have been changed to yyyy_ddd_zzzz_eee_eop.tab where yyyy and zzzz give the start and end year of data and ddd and eee give the start and end days of year. The PDS4 label file name is yyyy_ddd_zzzz_eee_eop.xml. 2025-07-05T00:00:00Z 2026-07-06T23:59:59Z Calibration Derived Earth Orientation Parameter file for radio science and other observations. Geodesy Other Investigation urn:nasa:pds:context:investigation:other_investigation.geodesy data_to_investigation EOP Analysis Literature Search Analysis leading to an EOP file uses data from very long baseline interferometry of compact radio sources and ranging/Doppler measurements to Earth orbiting satellites to determine the polar motion and nutation of the Earth's rotation axis. The data are collected using dozens of stations fixed to the Earth's surface but which are subject to tidal forces and tectonic motions. Earth Planet urn:nasa:pds:context:target:planet.earth data_to_target urn:nasa:pds:radiosci.documentation:dsn.trk-2-21:1997-08-04 data_to_document TRK-2-21 Software Interface Specification for EOP files. urn:nasa:pds:radiosci.documentation:document:folkner.1993 data_to_document A memo describing the models behind derivation of EOP files and the format and use of an EOP file. urn:nasa:pds:radiosci.documentation:document:moyer.1993 data_to_document A memo describing frame tie and nutation corrections for the Orbit Determination Program (ODP), the 1993 justification for the EOP. latest.short data_to_derived_source_product http://eop.jpl.nasa.gov The value of external_source_product_identifier is the name of the file downloaded from the server http://eop.jpl.nasa.gov or an equivalent. 2025_186_2026_187_eop.tab 2026-04-09T11:03:38 29511 57532fa76500065baf32038a34c765c6 Earth Orientation Parameter (EOP) files replace the older STOIC files. STOIC files include calibrations for UT1-UTC and polar motion. EOP files include these calibrations and, in addition, nutation correction parameters necessary to determine inertial station locations at the few-cm level. The EOP file describes rotation from a specific Earth-fixed reference frame to a specific inertial reference frame. In order to achieve cm-level accuracy for inertial station locations, the EOP file calibrations must be used according to a given set of models for Earth rotation and must be used with Earth-fixed and inertial frames consistent with those to which the Earth Orientation parameters refer. The models are described in urn:nasa:pds:radiosci.documentation:document:folkner.1993 and urn:nasa:pds:radiosci.documentation:dsn.trk-2-21:1997-08-04 The Earth-fixed and inertial frames for a given EOP file are given by parameters within the file. The Earth-fixed frame used by the EOP and STOIC files is consistent with the International Earth Rotation Service (IERS) terrestrial reference frame labeled ITRF93 while the inertial frame is consistent with the IERS Celestial Reference Frame labeled ICRF93. These frames are described in the IERS Annual Report for 1993 and in IERS Technical Note 18. EOP files are produced by the Tracking System Analytic Calibration (TSAC) group. A short version of the EOP contains Earth orientation values spanning slightly more than one year -- from approximately 9 months prior to creation of the file to approximately 3 months after the date of file creation, based on predictions. A long version is identical except that Earth orientation values are extended back to 1962. DSN and flight project navigation teams use Earth Orientation data in the process of reconstructing past orbits and generating orbit predictions. Other groups in navigation, mission design, tracking system and applications, and radio science also use EOP data.

0 518 7-Bit ASCII Text The EOP Header has 15 records. Record length is variable. Records are delimited by ASCII line-feeds. The records are: 1. The file title "JPL Earth Orientation Parameter File" 2. Date of the last data point 3. Date of the last prediction 4. A blank line except for the character "$" in the second position. 5. EOPLBL character*80 A record used to identify the EOP file; it provides the date of the last input datum (LD) and the last date for which predictions are given (PT). Variable UT1TYP has been placed at the end of the record. Only two values are allowed: UT1TYP=UT1R and UT1TYP=UT1. UT1R is UT1 with the effects of short-term tides removed. 6. EOPFNG character*80 This record gives the name of the program used to produce the EOP file, the date and time the file was generated, and the date and time the program was linked. 7. EOPUT1 character*6 This record indicates whether the data in the file contain TAI-UT1 or TAI-UT1R. The two possible values of this variable are 'UT1' and 'UT1R'. 8. EOPTYP character*6 This record is used by the Orbit Determination Program (ODP) to determine whether to use the EOP array or the UTPM STOIC (TP) array for the computation of Earth orientation. The allowed values of this variable are 'EOP' and 'STOIC'. 9. EOPTIM character*25 Date and time (UTC) of creation of the EOP file (format dd-mmm-yyyy hh:mm:ss.ffff). 10. EOPTRF character*6 This record gives the Terrestrial Reference Frame for station locations and site velocities to which the EOP parameters refer; currently the value assigned is 'ITRF93'. 11. EOPCRF character*6 This record gives the Celestial Reference Frame to which the EOP parameters refer; currently the value assigned is 'ICRF93'. 12-14. Three records providing column headers for the data which follow. 15. The marker "EOP=" denoting the beginning of the EOP data records.

Earth Orientation Parameters Table 518 367 The Table includes one or more records each with 8 fields including modified Julian Date, polar motion offsets, timing corrections to TAI, nutation corrections, and the date on which the corrections apply. The values cover approximately 9 months prior to the file creation (based on measurements) to approximately 3 months after file creation (based on predictions). Records have fixed lengths, fields are in fixed locations but are also delimited by commas, and records are delimited by ASCII line-feeds. Line-Feed 8 0 79 Modified Julian Date (MJD) 1 1 ASCII_Real 8 %8f day The modified Julian date for the remaining fields in the record. The number of days since midnight on November 17, 1858 (JD 2400000.5). Polar Motion X Coordinate 2 10 ASCII_Real 8 %8f milliarcsecond The X coordinate of polar motion in milliseconds of arc. One milliarcsecond is approximately 3 cm on the Earth's surface. Polar Motion Y Coordinate 3 19 ASCII_Real 8 %8f milliarcsecond The Y coordinate of polar motion in milliseconds of arc. One milliarcsecond is approximately 3 cm on the Earth's surface. TAI-UT1 4 28 ASCII_Real 11 %11f second The difference between International Atomic Time (TAI) and Universal Time 1 (UT1), where the latter is the instantaneous rotation angle of the Earth, determined from astronomical and satellite observations corrected for polar motion and measured in time units. TAI-UTC 5 40 ASCII_Real 6 %6f second The difference between International Atomic Time (TAI) and Coordinated Universal Time 1 (UTC), where the latter is Civil Time, formerly called GMT. By definition UTC runs at the same rate as TAI except for the introduction of leap seconds, which are required to keep UTC within 0.9 s of UT1. dPsi 6 47 ASCII_Real 8 %8f milliarcsecond The nutation correction for angle psi. dEps 7 56 ASCII_Real 8 %8f milliarcsecond The nutation correction for angle epsilon. Calendar Date 8 68 ASCII_String 11 %11s The calendar date corresponding to MJD in Field 1. Format is DD-MMM-YYYY.