Product: Bulletin A
IERS Bulletin A Volume XXXVIII Number 027 - Version metadata

Available downloads

Content

IERS Bulletin A contains Earth orientation parameters x/y pole, UT1-UTC and their errors at daily intervals and predictions for 1 year into the future.

The contents of IERS Bulletin A are divided into four sections:

1. General information including key definitions and the most recently adopted values of DUT1 and TAI-UTC.
2. Quick-look daily estimates of the EOPs determined by smoothing the observed data. This involves the application of systematic corrections and statistical weighting. The results are published with a delay of about one to three days between the date of publication and the last available date with estimated EOP.
3. Predictions of x, y, and UT1-UTC, up to 365 days following the last day of data. The predictions use similar algorithms based on seasonal filtering and autoregressive processing for x, y, and UT1.
4. The combination series for the celestial pole offsets. Bulletin A contains celestial pole offsets with respect to the IAU1980 Nutation theroy (dpsi and deps) and the IAU 2000 Resolutions (dX and dY), beginning on 1 January 2003.
Format

ASCII
Format Description

See contents of the file or
http://hpiers.obspm.fr/eoppc/bul/bulb/explanatory.html [.rtf]
Documentation

Explanatory supplement to IERS Bulletins A and B:
http://hpiers.obspm.fr/eoppc/bul/bulb/explanatory.html [.rtf]

Description of contents:
https://maia.usno.navy.mil/ser7/readme.bulla

Homepage of the IERS Rapid Service and Prediction Centre
https://maia.usno.navy.mil/
Title

IERS Bulletin A Volume XXXVIII Number 027
Data

section 1: DUT1 [sec], TAI-UTC [sec]
section 2: x [''], y [''], UT1-UTC [sec] and their errors
section 3: Predictions for x [''], y [''], UT1-UTC [sec]
section 4: dpsi, deps, dX, dY ([msec of arc]) and their errors

Data Points

section 1: 2
section 2: 38
section 3: 365
section 4: 2x20
Time Start

section 2: 2025-06-27
section 3: 2025-07-04
section 4: 2025-06-11
Time End

section 2: 1858-11-22
section 3: 2026-07-03
section 4: 2025-06-20
Time Interval

1 day
Accuracy 
Section 2:
                    Min       Max   Average
      x ["]:    0.00009   0.00009   0.00009
      y ["]:    0.00009   0.00009   0.00009
UT1-UTC [s]:   0.000009  0.000024  0.000017

Section 3: Estimated accuracies are:
    Predictions     10 d   20 d   30 d   40 d
        x,y ["]    0.004  0.007  0.010  0.013
    UT1-UTC [s]    0.0014 0.0024 0.0032 0.0040

Section 4: [msec. of arc]
                    Min       Max   Average
         dX:      0.128     0.588     0.438
         dY:      0.145     0.303     0.235
Keywords

EOP, Rapid, Bulletin A, Earth orientation parameter, Volume XXXVIII, Number 027
Frequency

weekly
Source

https://maia.usno.navy.mil/ser7/ [ser7.dat]
Created by

IERS Rapid Service Prediction Centre
Published by

IERS Rapid Service Prediction Centre
Date

2025-07-03
Contact

usn.ncr.navobsydc.mbx.eopcp@mail.mil
Distribution

onLine
Email Subscription

https://maia.usno.navy.mil OR https://www.iers.org/subscription.html
Volume

XXXVIII
Number

027