Products
The IERS Bulletin A (Rapid Service/Prediction) is available by 20:00 UTC
Thursday of each week.
Product
Description
Contains rapid determinations of Earth Orientation Parameters in a
human readable
format.
Polar motion, UT1-UTC, and length of day values since 02 January 1973
with dψ & dε using 1976 Precession/1980 Nutation Theory
(with 1 year of predictions)
Polar motion, UT1-UTC, and length of day values since 02 January 1973
with dX & dY using IAU2000A Nutation/Precession Theory (with 1 year of
predictions)
Polar motion, UT1-UTC, and length of day values since 01 January 1992
with dψ & dε using 1976 Precession/1980 Nutation Theory
Polar motion, UT1-UTC, and length of day values since 01 January 1992
with dX & dY using IAU2000A Nutation/Precession Theory (with 1 year of
predictions)
All EOP values since 01 May 1992 with dψ & dε using 1976
Precession/1980 Nutation Theory (with 15 days of predictions)
Polar motion and UT1-UTC in simple tabular format (with 90-day
predictions)
Format for "finals.all" and "finals.data"
Format for "finals2000A.all" and "finals2000A.data"
Format for "gpsrapid.out"
MD5 checksums for Earth Orientation Parameters data files
SHA512 checksums for Earth Orientation Parameters data files
Information
IERS Bulletin A reports the latest determinations for polar
motion, UT1-UTC, and celestial pole offsets (a.k.a, nutation offsets) at
daily intervals based on a combination of contributed analysis results
using data from Very Long Baseline Interferometry (VLBI), Satellite
Laser Ranging (SLR), and Global Positioning System (GPS) satellites.
Predictions for variations a year into the future are also provided.
Meteorological predictions of variations in Atmospheric Angular Momentum
(AAM) are used to aid in the prediction of near-term UT1-UTC changes.
- Contributors to the Bulletin
A combination
- Prediction coefficients
-
Explanatory supplement to IERS Bulletins A and B
- Interpolating IERS Earth
orientation data (IERS Gazette #13)
- Systematic
corrections applied to input data series
- Plots from the Bulletin A
- Statistical report for contributed
series
- Archive of changes to Bulletin A
-
Past issues of Bulletin A are archived at IERS
- Contents of IERS Bulletin A:
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 Earth Orientation Parameters (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.
Relevant References
Combination
- McCarthy, D. D. and Luzum, B. J., 1991, "Combination of precise
observations of the orientation of the Earth," Bull. Geod.,
Vol. 65, pp. 22-27.
- Luzum, B. J., Ray, J. R., Carter, M. S., and Josties, F. J., 2001,
"Recent Improvements to IERS Bulletin A Combination and Prediction,"
GPS Solutions, Vol. 4(3), pp. 34-40.
- Wooden, W. H., Johnson, T. J., Carter, M. S., and Myers, A. E.,
2004, "Near Real-Time IERS Products," Journees Systemes de
Reference Spatio-Temporels 2003, pp. 160-163.
Prediction
- McCarthy, D. D. and Luzum, B. J., 1991, "Prediction of Earth
Orientation," Bull. Geod., Vol. 65, pp.
18-22.
- Luzum, B. J., Ray, J. R., Carter, M. S., and Josties, F. J., 2001,
"Recent Improvements to IERS Bulletin A Combination and
Prediction," GPS Solutions, Vol. 4(3),
pp. 34-40.
- Johnson, T. J., Luzum, B. J., Ray, J. R., 2005, "Improved near-term
Earth rotation predictions using atmospheric angular momentum
analysis and forecasts," J. Geodyn.,
Vol. 39, pp. 209-221.