Rapid Assessment Method for the Main Survey Camera Images of the Chinese Space-station Survey Telescope

The Chinese Space-station Survey Telescope (CSST) is a flagship space-based astronomical observatory planned and developed under the China Manned Space Program. It is characterized by a wide field of view, high image quality, broad wavelength coverage, and the ability for on-orbit maintenance and upgrades. During mission operations, the Payload Operation and Application Center must rapidly analyze the images acquired by the main survey camera to derive key diagnostic information on the optical system—including image quality, focus status, and charge-coupled device (CCD)-center projection offset—thereby ensuring the effective implementation of scientific observations. To meet these engineering requirements, this study proposes a rapid assessment method for single-CCD images of the main survey camera. By leveraging astronomical source detection and stellar catalog matching, the method establishes a correspondence between pixel and celestial coordinates, enabling image quality assessment, focus evaluation, and CCD-center projection offset calculation. The complete workflow is primarily validated using simulated multiband imaging data from the CSST main survey camera. For slitless spectroscopic images, the study focuses on the detection of candidate zeroth-order sources and the measurement of point spread function parameters, providing vital auxiliary data to support on-site operations. Tests using simulated data from the CSST main survey camera, together with observational data from the Hubble Space Telescope and the Lijiang 2.4 m Telescope, demonstrate that the proposed method can rapidly and stably output key assessment parameters.