  From the mid-19th century to the end of the 20th century, photographic plates
served as the primary detectors for astronomical observations. Astronomical
photographic observations in China began in 1901, and over a century, a total
of approximately 30,000 astronomical photographic plates have been captured.
These historical plates play an irreplaceable role in conducting long-term,
time-domain astronomical research. To preserve and explore these valuable
original astronomical observational data, Shanghai Astronomical Observatory has
organized the transportation of plates taken at night from various stations
across the country to the Sheshan Plate Archive for centralized preservation.
For the first time, plate information statistics was performed. On this basis,
the plates were cleaned and digitally scanned, and finally digitized images
were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference
star catalog, astrometric processing has been carried out successfully on
15,696 single-exposure plates, including object extraction, stellar
identification, and plate model computation. As a result, for long focal length
telescopes, such as the 40cm double-tube refractor telescope and the 1.56m
reflector telescope at the Shanghai Astronomical Observatory and the 1m
reflector telescope at the Yunnan Astronomical Observatory, the astrometric
accuracy obtained for their plates is approximately 0.1" to 0.3". The
distribution of astrometric accuracy for medium and short focal length
telescopes ranges from 0.3" to 1.0". The relevant data of this batch of plates,
including digitized images and stellar catalog of the plates are archived and
released by the National Astronomical Data Center. Users can access and
download plate data based on keywords such as station, telescope, observation
year, and observed celestial coordinates.
