活动光栅测微器的精度分析

Analyzing the Accuracy of the Photoelectric Moving-slit Micrometer

ＤＣＭＴ的主测微器采用一种活动Ｖ形光栅扫描模式．根据对人造准直光源像的测量分析，研究了主测微器扫描测量的系统精度．研究结果表明．主测微器系统精度优于０＂．００９，为天体位置的高精度测量提供了良好的条件．

A photoelectric moving-slit micrometer is used to record the transits of stars and artificial light sources on the DCMT. In order to scan the different light sources or star in the same field of view, the scan region of the micrometer is divided into two parts. For the observation of the star,the slit moves backwards and forwards with tracking the star motion. The slit scans artificial light sources back and forth without tracking. In our case, the collimation image is fixed in a short time. It can be used to study the systematic stability of the micrometer.A median method is presented to estimate the position of the image. The centre position of a recorded profile is derived from a linear interpolation or from a quadratic interpolation as equations (3)and (9).The mean error of the estimation is given in equation (4) or (5) for the linear interpolation and in equations(11)and (12) for the quadratic interpolation. We have studied the difference of two inone. A time series of photon counts is recorded by the scanning of micrometer. Equations (13)and (14) give the transformation from the measured time series to the location of the micrometer.Therefore,the components in right ascension and declination of the image position can be derived as given in equation (16). From the repeated measurements of the collimationimage, we have studied the systematic accuracy of the micrometer. It shown that the accuracy of a single measurement is better than 0'.009.