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IERS Message No. 326                                   February 08, 2017
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Revision of IERS Earth Rotation Series effective 9 February 2017


The current series of IERS Earth Orientation Parameters (EOP) provides
the official transformation between the International Celestial
Reference Frame (ICRF) and the International Terrestrial Reference Frame
(ITRF).

In order to be consistent with the recently released ITRF2014, the IERS
EOP C04 is being revised. The new solution 14 C04 is the reference
solution starting close to the middle of February, 2017. Relative to
08 C04, changes in the EOP series from 2011 consist of

   1) A small bias in x-pole and y-pole under -50 +/- 25
      microarcseconds in the sense of x or y (14 C04) - x or y (08 C04);

   2) Small changes in UT1-TAI that are under 5 microseconds; and

   3) Small changes in celestial pole offsets that are under 
      20 microarcseconds. 

Other IERS EOP series (Bulletin B, C01) will be expressed in this new
system consistent with ITRF2014 starting with solutions starting close
to the middle of February 2017.

It is anticipated that the Rapid Service/Prediction Center solutions
(Bulletin A and daily) will be expressed in the new system starting with
solutions made on 9 February 2017.

The new version of the C04 computed in the new system is now called
IERS 14 C04.

IERS 14 C04 series will be available at:
ftp://hpiers.obspm.fr/iers/eop/eopc04

A notice describing its characteristics will be available at:
ftp://hpiers.obspm.fr/iers/eop/eopc04/C04.guide.pdf

Past version of C04 can be downloaded until 2018-03-01 from:
ftp://hpiers.obspm.fr/iers/eop/eopc04_08/


Thank you for your cooperation

C. Bizouard, Earth Orientation Center,
     Paris Observatory
C. Hackman, N. Stamatakos, IERS Rapid Service/Prediction Center,
     US Naval Observatory


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