[Difx-users] [Non-DoD Source] Re: [Unrestricted] Getting EOP's {External} {External}

Mon Jul 21 16:09:20 EDT 2025

Hi all,

I asked Maria Davis of the IERS Rapid Service / Prediction Center where to find EOPs. Her response is below. If you have any questions, feel free to reach out to her; she is not on the difx-user mailing list but she is cc’ed and her email address is included below.

Best regards,

Sara Hardin
Earth Orientation Department, VLBI Division
U.S. Naval Observatory
3450 Massachusetts Ave. NW
Washington DC 20392, USA
email: sara.e.hardin.civ at us.navy.mil

------

Hi Sara,

Thanks for forwarding. The official International standard for EOPs is the C04 (Paris Observatory: https://hpiers.obspm.fr/iers/eop/eopc04/eopc04.1962-now) and Finals (USNO: https://maia.usno.navy.mil/ser7/finals2000A.daily.extended) series produced by the IERS Earth Orientation Centre and IERS Rapid Service / Prediction Centre, respectively.

EOP data files, Bulletins A and B (and corresponding Finals and C04 series), can also be found on the IERS website (https://www.iers.org/IERS/EN/DataProducts/EarthOrientationData/eop.html). CDDIS also hosts the Finals files (https://cddis.nasa.gov/archive/products/iers/finals2000A.daily.extended). However, IERS and CDDIS should be treated as backups to the original sources provided above.

Depending on how the EOPs will be used, someone may also want a 3rd EOP series to compare values. In that case, I like to use the JPL SPACE solution (https://euler.jpl.nasa.gov/predictions/latest_midnight.eop).

I’m not sure how the files linked below are generated/assembled, and therefore can’t speak to their validity. To support DiFX, I strongly recommend using an official IERS EOP series. Which series to use depends on the specific use-case. Happy to discuss further if you have any specific scenarios.

Kind regards,
Maria

Maria Davis (she/her)
Lead Scientist, IERS Rapid Service / Prediction Center
Earth Orientation Department
U.S. Naval Observatory
3450 Massachusetts Avenue NW
Washington, DC 20392
maria.a.davis33.civ at us.navy.mil<mailto:maria.a.davis33.civ at us.navy.mil>

From: Difx-users <difx-users-bounces at listmgr.nrao.edu> on behalf of Adam Deller via Difx-users <difx-users at listmgr.nrao.edu>
Date: Sunday, July 20, 2025 at 10:30 PM
To: Leonid.Petrov at lpetrov.net <Leonid.Petrov at lpetrov.net>
Cc: Stuart Weston <stuart.weston at spaceops.nz>, difx-users at listmgr.nrao.edu <difx-users at listmgr.nrao.edu>
Subject: [Non-DoD Source] Re: [Difx-users] [Unrestricted] Getting EOP's {External}
personally I use wget ftps://gdc.cddis.eosdis.nasa.gov/vlbi/gsfc/ancillary/solve_apriori/usno_finals.erp<http://gdc.cddis.eosdis.nasa.gov/vlbi/gsfc/ancillary/solve_apriori/usno_finals.erp>. gdc still exists, it just doesn't support ftp any more.

Cheers,
Adam

On Mon, 21 Jul 2025 at 11:56, Leonid Petrov via Difx-users <difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>> wrote:
Stuart,

>  How do people get the EOP's these days ?

   https://earthrotation.smce.nasa.gov/

Leonid

> On 2025-07-20 21:39, Stuart Weston via Difx-users wrote:
> We have a server that hasn't been used in anger for a while. It has
> an install of DiFX on it which was "working".
>
>  The "geteop.pl<http://geteop.pl/>" doesn't appear to work any more. It is trying to use
> :
>
>  ftp://gdc.cddis.eosdis.nasa.gov<ftp://gdc.cddis.eosdis.nasa.gov/>
>
>  I don't get a response from it.
>
>  I have found EOP's here : https://eop2-external.jpl.nasa.gov/
>
>  But not sure how to map the columns to what DiFX requires.
>
>  How do people get the EOP's these days ?
>
>  Dr Stuart Weston
>
>  PhD, MPhil(Hons.), BSc(Hons.)
>  Warkworth Station Manager
>  121 Satellite Station Road, Warkworth 0983
>
>  Space Operations New Zealand Ltd
> PHONE +64 21 713 062
> ADDRESS Hargest House, 62 Deveron Street, PO Box 1306, Invercargill
> 9840, New Zealand
>
>  www.spaceops.nz<http://www.spaceops.nz/> [1]
>
>
>
> Links:
> ------
> [1] https://spaceops.nz/
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> Difx-users at listmgr.nrao.edu<mailto:Difx-users at listmgr.nrao.edu>
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--
!=============================================================!
Prof. Adam Deller
Centre for Astrophysics & Supercomputing
Swinburne University of Technology
John St, Hawthorn VIC 3122 Australia
phone: +61 3 9214 5307
fax: +61 3 9214 8797
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