ASTROMETRY OF THE PLATES OF THE DWA DIGITIZED WITH THE MICROTEK SCANMAKER 9800XL TMA SCANNER

摘要

A detailed testing of the Microtek ScanMaker 9800XL TMA scanner aimed at large-scale plates ($300imes300$,mm and larger) digitization has been undertaken. The evaluation of the accuracy of star image centering and darkening determined from the newly developed method in MIDAS/ROMAFOT environment has been carried out from the comparison of digitized images of different greyscale depth(16 and 8 bits). The random instrumental errors have been found to reach $pm$0.0035 px and $pm0.011^{m}$ for position and magnitude accordingly. The estimations of repeatability of positional and photometric errors of the scanner have been received from four consecutive scans of the same plate obtained with 1200 dpi. The positional errors are $pm0.034div0.059$ px and photometric ones are $pm0.012div0.014^m$ for stars down to $13^m$. For the plates of DWA telescope positional rms errors are $pm0.25''$ and $pm0.35''$ for RA and DEC accordingly, photometric errors are $pm0.20^{m}$ with the Tycho-2 catalogue as reference.