Paris Observatory Geodetic VLBI Center

Celestial reference frame 2025c

5857 quasars

This page presents the current VLBI celestial reference frame established at Paris Observatory using the full set of available geodetic VLBI multibaseline experiments at S/X (no VGOS, no K-band). The catalog of positions is compared against the current fundamental reference frame (ICRF3 with native formal errors).

Technical description: see the global solution page,
Radio source coordinates at epoch 2015.01.01 (same as global solution).

Sky maps of error ellipse semi-major axis (EESMA).

Sky maps of error ellipse position-angle (EEPA).

Sky maps of RA-Dec correlation.

Sky maps of source mean observation epoch.

Sky maps of number of sessions.

EESMA versus the number of delays.

Distribution of errors in RA and Dec.

(Left) Arc length between ICRF3 and opa2025c and (Right) its position-angle.

Distribution of (Left) the angular separation between ICRF3 and opa2025c, (Middle) the position-angle between ICRF3 and opa2005b positions, and (Right) the normalized separation.

The (Left) angular and (Middle) normalized separations vs. the number of delays, and (Right) the normalized separation as a function of the angular separation. The red line on the normalized separation scale is the limit beyond which there is no expected survival source for a Rayleigh distribution of parameter 1. Conversely, the red line on the angular separation scale is the angular separation leaving only 5% of the sample beyond.

(Left) Transformation parameters between ICRF3 and opa2025c adjusted on positional differences after removal of outlier sources following the method explained in Charlot et al. (2020) and (Right) their correlations.

Decimation solution following the method used in Charlot et al. (2020), yielding that the errors in the catalog should be inflated by a scale factor of 1.5 and a noise floor of 20 μas. The plot below displays the wrms noise for subsets of 50 sources as a function of the number of sessions in which a source was observed and median formal uncertainty in each subset.

Sky maps of error ellipse semi-major axis (EESMA).

Sky maps of error ellipse position-angle (EEPA).

Sky maps of RA-Dec correlation.

Sky maps of source mean observation epoch.

Sky maps of number of sessions.

EESMA versus the number of delays.

Distribution of errors in RA and Dec.

(Left) Arc length between ICRF3 and opa2025c and (Right) its position-angle.

Distribution of (Left) the angular separation between ICRF3 and opa2025c, (Middle) the position-angle between ICRF3 and opa2005b positions, and (Right) the normalized separation.

The (Left) angular and (Middle) normalized separations vs. the number of delays, and (Right) the normalized separation as a function of the angular separation. The red line on the normalized separation scale is the limit beyond which there is no expected survival source for a Rayleigh distribution of parameter 1. Conversely, the red line on the angular separation scale is the angular separation leaving only 5% of the sample beyond.

(Left) Transformation parameters between ICRF3 and opa2025c adjusted on positional differences after removal of outlier sources following the method explained in Charlot et al. (2020) and (Right) their correlations.