IVS Contribution to ITRF2020

In 2020, the ITRS Center of the International Earth Rotation and Reference Systems Service (IERS) will begin assembling the next realization of the International Terrestrial Reference Frame, ITRF2020. VLBI Analysis Centers are encouraged to submit their station and velocity analysis for this effort. This web page provides guidelines for Analysis Centers to use in their ITRF2020 submissions, as well as files to support the analysis.

This web-page will be updated as information changes. A summary of the changes is given at the bottom of the web-page to help you identify things that might have changed since your last visit.

ITRF2020 Participation Call and Checklist

• Call for Participation from Zuheir Altamimi
• Checklist for submissions (version 2020Jan13).

Tentative Schedule

• 2020-Aug-01: Initial AC submission to IVS Combination Center. Combination Center will provide feedback to ACs on any problems encountered.
• 2020-Nov-01: First combined solution from IVS Combination Center. Combination Center will provide feedback to ACs on any problems encountered.
• 2020-Nov-01-2020-Jan-20: ACs submit additional sessions to Combination Center as they become available.
• 2021-Feb-10: IVS submission for ITRF2020 due.
• 2021-Apr-10: Revised IVS submission for ITRF2020 due.

IVS Analysis Centers Contributing to ITRF2020

This list was last updated on 2021Feb10. It reflects the session list as of 2021Jan15.

Sessions submitted

Sessions submitted as of 2021Feb10

• S/X Session list
• VGOS Session list

Session list

All IVS Analysis Centers should submit results for the complete list of IVS sessions for ITRF2020. This list will change over time as new sessions complete processing and preliminary analysis. The most recent list is immediately below. If you have problems finding any of the sessions on the list please let us know. Conversely, if there are sessions that we have missed, please let us know so that we can update the list. This will be the first time the IVS submits VGOS data. The VGOS and S/X data sessions are listed separately below.

We exclude all sessions shorter than 24 hours or fewer than 3 stations. We also exclude some other problematic sessions.

The 2021Apr06 S/X session list is presented below. 250 session were removed compared to the 2020Dec18 session list. These are sessions which are shoter than 15 hours or problematic in some other way.

• S/X Session list

• VGOS Session list

Special Considerations for ITRF2020

Handling of Sources

In contrast to previous ITRF submissions, this submission will include source coordinates. To prevent singularity problems with the normal equations if the number of observations is too small, it is strongly recommended that if a source has fewer than 4 good observations in a session that no observations involving that source be used in constructing the normal equations.

Pressure Loading

In contrast to previous IVS submissions to ITRF, this submission will include the effect of atmospheric pressure loading. Since the other space geodetic techniques still (!!) do not routinely include this, we need to include information in the SINEX file to allow for the removal of pressure loading.

• A memo (written 2020Jan14) that describes the necessary extensions to the SINEX format is here.
• A SINEX file produced by Solve for 08AUG12XA without a priori pressure loading.
• A SINEX file produced by Solve for 08AUG12XA with a prioiri pressure loading.

New models in ITRF2020

The following models are new in ITRF2020. If you do not use these models your submission will be rejected. The first two are for all Space Geodetic techniques,while the second two are for VLBI only.

• New mean pole-tide model.
• Desai&Sibois/Egbert HF-EOP model. Information and software can be found here
• Galactic aberration. See the final report. of the WG on galactic aberration.
• Gravitational deformation of VLBI antennas.

Auxiliary files for use in ITRF2020

For the IVS submission to ITRF2020 all ACs should use the same axis-offsets. The GSFC VLBI group has generated a file which contain axis-offsets in a form suitable for use by calc/solve. The axis offset values came from ground surveys if they were available, and from a large global solution otherwise.

• ITRF2020 Axis Offsets (updated 2020Apr14)

You can also use the information in antenna_info.txt maintained by Axel Nothnagel which also contains the thermal deformation models you should use.

• antenna_info.txt

There are other files to be used in ITRF2020. The IVS Analysis Coordinator will notify you if these files change.

• Gravity deformation file (2019Nov21)
• A priori mean gradient file
• VLBI station eccentricities (2019Dec19)

History of changes

• 2021Jan15: Updated session list.
• 2020Dec04: Updated session list. Removed links to old lists.
• 2020Nov16: Updated session list.
• 2020Oct23: Updated session lists; updated sumbitted sessions.
• 2020Sep30: Updated submitted session lists. Modified AC table: Added Onsala, number of sessions.
• 2020Aug19: Updated AC table, submitted sessions table.
• 2020Aug15: Added new links to tables which show which ACs have sumbitted which sessions. Some reorganization
• 2020Aug05: Added USNO to AC list. Updated Session lists
• 2020May06: Added DGFI-TUM and IAA to AC list.
• 2020May06: Added tentative schedule. Updated session files. Updated axis offset file. Updated AC list
• 2020Apr24: Updated axis offset files.
• 2020Jan30: Updated IVS AC contributing to ITRF2020.
• 2020Jan27: Added ITRF2020 axis offset file. Updated information on sesssions to include VGOS session.
• 2020Jan16: Added section on participation in ITRF2020.
• 2020Jan14: Major revamp. Include session list, new eccentricity file, submission checklist, information about pressure loading.
• 2019Nov21: New gravity deformation file
• 2019Aug20: Preliminary version.