Figure F3. Hole 1203A magnetic and orientation logs from the orientated Göttingen Borehole Magnetometer (GBM) and comparison of the direct (optical-gyro based) estimation of the tool rotation with the proposed filtering algorithm. A. Lithology. B. Intensity of the total magnetic field (F). C. Inclination (Inc). D. Declination (Dec). E. Tool declination (tdec) obtained from raw magnetic records Fx, Fy, and Fz, integrating the local value of the declination and the tool rotation component (tdec = Dec + Rot). F. Hole shape. G. Rotation (Rot) directly recorded by the GBM gyroscopic system. H. Indirect GBM rotation (rot) obtained by filtering tdec using a 4-m-wide cosine filter. I. Residual (rot) between Rot and rot.