The Representation of OTA Images’ Astrometric Results with WCS-SIP Coefficientstwo

Cross-matching the sources in the observed image with the star catalogs or earlier records is a necessary procedure for detecting the position or brightness variation of a specific source in the Optical Telescopes Array (OTA) survey. Therefore, knowing the celestial positions of these objects on the observed image is prerequisite. A method based on matrix manipulation is applied to converting the existing plate constants of OTA images into the World Coordinate System (WCS) and Simple Imaging Polynomial (SIP) coefficients, and recording such mapping relations on the FITS (Flexible Image Transport System) files of OTA for the convenience of use. The improvement on the astrometry of OTA resulted by this method, as well as the discussion about some problems of the OTA astrometry are also presented.