Geomagnetic data from 3-axis magnetometer and the IGRF model (tilite - eccentric dipole model) were used to determine the attitude of a satellite. We compared the values of the geomagnetic model with the magnetometer data and two attitude angles, called $alpha$ -angle and $eta$-angle respectively, were calculated. From these angles we calculated simple bounds, $gamma1$ and $gamma2$, on the true attitude angle $gamma$, which is used to detemine attitude, between the z-axis and the local vertical. And then we investigated conditions of attitudes of UoSAT-11, 14, 22.