Changes in 20 C04 / Bulletin B

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2023 February 14

The 14 C04 ERP solution is replaced by the series 20 C04, consistent 
with ITRF 2020. Repertory remains the same. The format is changed, pole rates 
coordinates are included, except for the file eoppc04_IAU2000.62-now. 

See https://hpiers.obspm.fr/iers/eop/eopc04/eopc04.txt for the description 
of the new solution. 

The 14 C04 series will be produced until a non defined date, and 
put in the neighbouring directory eopc04_14.  

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2023 April 8

Maria Davis (USNO) noticed that the pole coordinates at 0hUTC 
were unsually noisy over the period 2021-April 2023. The problem was fixed. 

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2023 April 21

Until 2023 April 6, extrapolation of the biases of the inter-technique pole coordinate solution 
entering the C04 over 2019-2021 to the period 2021-2023, and removed accordingly from those series 
before combination. But, that caused spurious biases with other pole coordinate series, 
as Maria Davis points out biases, especially in x: +30 ľas in the differences USNO Final / JPL - C04. 

From April 21, intra-technique solutions entering in the C04 over the period 2021-current date are 
aligned with the IGS repro3 solution recalculated in the ITRF 2020 by Paul Rebishung (IGN).

The UT1, celestial pole offsets dX, dY are aligned with ICRF 3, namely the IVS quarterly solution 
released on 2022 0ctober 31.

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2023 April 24

From that date we produce of version of the 20 C04 celestial pole offsets 
dPsi, dEps with respect to IAU 1980 precession-nutation model and named: 
eopc04.dPsi_dEps.IAU1980.1962-now.   

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2023 December 12

On December 5 Robert Heinkelman (GFZ) reported to me outliers in UT1 values 
during the year 2017, confirmed by Manuela Seitz (TU Munchen). We fixed the origin of the 
problem and recalculated the C04 UT1 values for that period. The former versions of the C04 
series were put in the folder ./archive_11_12_2023.