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International Earth Rotation and Reference Systems Service

ICRF3 - The 3rd realization of the International Celestial Reference Frame

The International Celestial Reference Frame (ICRF) realizes an ideal reference system, the International Celestial Reference System (ICRS), by precise equatorial coordinates of extragalactic radio sources observed in Very Long Baseline Interferometry (VLBI) programmes.

Content

This dataset provides the equatorial coordinates of extragalactic radio sources observed at J2000.0 using Very Long Baseline Interferometry (VLBI) across the S/X, K, and X/Ka frequency bands, with the S/X-band remaining the conventional reference for geodesy, Earth orientation, and satellite orbit determination.

 

Number of objects

S/X

4536

K

824

X/Ka

678
AccuracyThe uncertainties in the coordinates are provided for each object and are given in the following ranges:
Right Ascension [s]Declination ["]

S/X

0.00000202 - 0.008992650.0000303 - 0.2507685

K

0.00000245 - 0.000865950.0000613 - 0.0118579

X/Ka

0.00000291 - 0.004460180.0000470 - 0.0735481
Updates

updates to the ICRF are released at irregular intervals, typically every few years.

Public access
Format

For a detailed description of the format, refer to the contents of the data file.

Documentation

Charlot, P., Jacobs, C. S., Gordon, D., Lambert, S., de Witt, A., Böhm, J., Fey, A. L., Heinkelmann, R., Skurikhina, E., Titov, O., Arias, E. F., Bolotin, S., Bourda, G., Ma, C., Malkin, Z., Nothnagel, A., Mayer, D., MacMillan, D. S., Nilsson, T., & Gaume, R. (2020). The third realization of the International Celestial Reference Frame by very long baseline interferometry. Astronomy & Astrophysics, 644, A159. https://doi.org/10.1051/0004-6361/202038368

Product center

IERS ICRS Centre