Fig. 6From: Evaluation of the first three years of Vgos 24 h sessions using a Kalman filter with C5++The mean biases for nutation and polar motion estimates when fixing the sources to ICRF3 (S1) and the VA-ICRF3 (S2). The mean bias of celestial pole offset in the X axis is \(-0.8~\mu\)as in the second case and not easily discernible in the figureBack to article page