Establishment Of CCD Drift-Scan System And Observing And Positioning For GSS With It

Based on camera S1C077, having success with developing special exteriorsynchronizer in order to achieve CCD drift scan mode which can apply to astronomyobservation more advantageously. To avoid many questions with full frame CCDdrift scan mode, part frame CCD drift scan mode was achieved by software. In orderto obtain good circular images of reference stars and GSS (Geo Stationary Satellites),part frame CCD drift scan mode and stare mode were carried out by turns. Makingand implementing observation plan for GSS were discussed also.The elementary version of special software for data reduction was finished byourselves. This special software was called SHAO_GSS_Positioning. The mainfunctions of this software includes detecting stars in FTS file automatically,matching and identifying reference stars automatically, obtaining parameters ofsuitable plate model and magnitude mode of CCD automatically and finally gettingthe optical coordinates and visual magnitudes of GSS. By the way, UCAC2 is used tobe the catalogue of reference stars.More than fifty GSS were observed by this system and their coordinates andmagnitudes were computed by SHAO_GSS_Positioning. The total internal errors ofoptical positioning results was about 0.5as. There were two main part of error source,the local reference system which was about 0.15as and the measurement coordinates of objects which were about 0.45as. The better observation condition the station isand the better optical performance the telescope is, The higher precision-position forGSS will be obtained.According to the observing process and the matching result of the previous testwhich purpose was surveying GSS in one small sky area, a new survey plan wasmade. The main principle of the new survey plan is always having telescope point tothe equator in order to avoid missing the objects which will pass by the area ofequator. The advantages and efficiency of the new survey plan were analyseddetailedly also.Usually, GSS objects are observed with stare mode so that images of referencestars will be stretched because of the relative movement between telescope and stars.Therefore, a new centering method, that is MGC (mean-geometric-centering), wasapplied to compute centers of stars. MGC is more precise than moment forcomputing centers of stretched stars images. In fact, MGC is more suitable forsaturated stats images also.