Paris Observatory Geodetic VLBI Center

Celestial reference frame 2025b

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.

EESMA versus the number of delays.

Distribution of errors in RA and Dec.

(Left) Arc length between ICRF3 and opa2025b and (Right) its position-angle.

Distribution of (Top-left) the angular separation between ICRF3 and opa2025b, (Top-right) the normalized separation, (Bottom-left) the position-angle between ICRF3 and opa2005b positions, and (Bottom-right) the angular vs. normalized separation. The vertical, red line represents the normalized separation beyond which there is no expected survival source for a Rayleigh distribution of parameter 1; The horizontal, red line is the angular separation leaving only 5% of the sample beyond.

(Left) Transformation parameters between ICRF3 and opa2025b adjusted on positional differences after removal of outlier sources following the method explained in Charlot et al. (2020) and (Right) their correlations.

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.

EESMA versus the number of delays.

Distribution of errors in RA and Dec.

(Left) Arc length between ICRF3 and opa2025b and (Right) its position-angle.

Distribution of (Top-left) the angular separation between ICRF3 and opa2025b, (Top-right) the normalized separation, (Bottom-left) the position-angle between ICRF3 and opa2005b positions, and (Bottom-right) the angular vs. normalized separation. The vertical, red line represents the normalized separation beyond which there is no expected survival source for a Rayleigh distribution of parameter 1; The horizontal, red line is the angular separation leaving only 5% of the sample beyond.


(Left) Transformation parameters between ICRF3 and opa2025b adjusted on positional differences after removal of outlier sources following the method explained in Charlot et al. (2020) and (Right) their correlations.