Bulletin A Contents
The contents of the Bulletin A are described below.
Section 1: General information including key definitions and the most recently adopted values of DUT1 and TAI-UTC.
Section 2: Quick-look daily estimates of the EOPs determined by combining the observed data. This involves the application of systematic corrections and statistical weighting. The results are published with a delay of about one day between the date of publication and the last available date with estimated EOP. Also, the final EOP values, from the IERS Earth Orientation Parameter Product Center (EOP PC), are published monthly when available.
Section 3: Predictions of x, y, and UT1-UTC, for up to 360 days following the last day of data in Section 2. Predictions combine the deterministic component of the EOPs with an autoregressive process that accounts for the stochastic components in the EOPs.
Section 4: Combination and prediction of celestial pole offsets dpsi and depsilon are provided when new VLBI observations become available. The results are published with a delay of about one week between the date of publication and the last available date with estimated offsets. Also, the final celestial pole offsets, from the IERS EOP PC, are published monthly when available.