A CCD Detector Attached to the Lower Latitude Meridian Circle——(Ⅱ) The Determination and Related Correction of A Few Constants of the Detector

The influences of the errors of making and mounting of the CCD chip on the nonorthogonality of the two measuring coordinate axes and the unequality of the scales of the two axes arc described and a method for determining directly the errors on the LLMC is proposed. Another method for determining the scales by means of the observation of a star and for determining the temperature-dependent scales by using the available self-collimation system of the LLMC is also introduced. It can be ensured from the above-mentioned determinations that the influence of the errors on the position of the image of a star on the edge of the CCD's field of view is limited within ±0.001 pixel. In addition, the influence of the projection effect during the tracking observation of a star by rotating the horizontal axis of the instrument is also derived in detail and the correction formula are given. From the derivation it can be seen that the observation of stars carried out by rotating the horizontal axis of the circle is favourable to the accurale determination and correction of the error.