[IGSMAIL-6273] Re: Tranformation parametres between IGS reference frames realizations

[jim.ray at noaa.gov]

Author: Jim Ray, IGS Analysis Center Coordinator (ACC)

Dear Stefano,

IGS Mail is not the best forum for general user questions.  However,
since your question is one of importance to many people, please let
me give some guidance (though hopefully most subscribers know these
things already).

At the ACC website -- http://acc.igs.org/ -- information about dealing
with past frame changes is given under the "SP3 Satellite Files" heading.
However, more recently, better advice for nearly all users is to use the
IGS reprocessed ("repro1") products.  Information about the release of
these products last April is given under "General Information" at the 
ACC site or directly in the email message at:

  http://igscb.jpl.nasa.gov/mail/igsmail/2010/msg00084.html

Essentially, the new consistently reprocessed product files are in the
usual CDDIS product directories but in the lower "repro1" subdirectories.
The IGS05 frame (aligned to ITRF2005 but with relative -> absolute
antenna calibration corrections applied) is used throughout.

All the necessary background and evaluation information is given at
the repro1 website:  http://acc.igs.org/reprocess.html .

Hope this satisfies your needs.

--Jim



----- Original Message -----
From: Stefano Ferri <stefano.ferri9 at unibo.it>
Date: Sunday, September 26, 2010 8:41 am
Subject: [IGSMAIL-6272] Tranformation parametres between IGS reference	frames realizations
To: "igsmail at igscb.jpl.nasa.gov" <igsmail at igscb.jpl.nasa.gov>

> Dear list,
> 
> I've just subscribed to IGSmail in the hope to solve a problem.
> 
> I'm analyzing the time series of some IGS stations. Since the time 
> interval spans from 1999 to 2009, I have 3 reference frame to dial 
> with: IGS97, IGS00 and IGS05. I need to remove the jumps due to those 
> reference frame changes, and I would like to transform all in the IGS05.
> Therefore, looking on the ITRF website, I've found some documentation 
> here:
> 
> 
> 
> where  transformation parameters between all the ITRF reference frames 
> are reported. These are not parametes between IGS reference frames, 
> but since I've not found them, I've tryed anyway. After the Helmert 
> transformation, I've converted cartesian coordinates into North, East 
> and Up components. While North and East were succesfully corrected, 
> the Up component shows a jump 2006, and a smaller one in 2001,  when 
> there were the switches from IGS97 to IGS00 and from IGS00 to IGS05.
> 
> Since I've not found transformations parameters between IGS 
> realization, but only between ITRFs, I would like to know if there is 
> a webpage or some documents repporting the official parameters. IGS' 
> are aligned to ITRFs, but is it correct to use the parameters reported 
> in the ITRF website for transformations between IGS realizations of 
> the ITRF? Is there something like IERS' technical notes containing 
> IGS-related informations?
> Could it be possible that the switch from relative to absolute antenna 
> calibrations causes the jump in the Up component? If so, how to 
> estimate it?
> 
> 
> Thank you in advance for any reply.
> 
> Best regards,
> Stefano Ferri
> 
> 
> -- 
> Stefano Ferri
> Department of Physics - Sector of Geophysics
> University of Bologna
> Viale Berti Pichat 8, 40127 Bologna - Italy
> Tel. +39 051 2095066
> Fax  +39 051 2095058
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