Recently, the Chinese Plate-Digitizing Project has made significant new progress. Mingyang Ma et al. published a paper in which they performed photometric calibration of 15,696 single-exposure plates in this study. Among them, 1,539 plates are from the Shanghai Astronomical Observatory (SHAO), 4,980 from the National Astronomical Observatories of China, Chinese Academy of Sciences (NAOC), 8,283 from the Purple Mountain Observatory (PMO), 753 from the Yunnan Observatories (YNAO), and 141 from the Qingdao Observatory (QDO). The typical limiting magnitude range of the plates from each observatory is 12.2-18.5 mag, collectively covering the period from 1901 to 1999.
These photometric catalogs contain 33,282,558 unique sources with 229,271,500 independent observations. Simultaneously, they presented a catalog of suspected variables numbering in the millions. The light curves of these suspected variables have also been collected. The relevant data are currently available at Digitized Data of China Astronomical Plates: Photometric Catalogs of Single-exposure Plates and Variable Candidates | NADC
This dataset will provide a valuable resource for conducting long-term, temporal-scale astronomical research!
The paper is currently available for viewing on Arxiv at the link:[2507.10270] Digitization of Astronomical Photographic Plate of China: Photometric Calibration of Single-exposure Plates and Release of Photometric Catalogs
It is worth mentioning, however, that the paper did not conduct further processing of these suspected variables. Therefore, most of the variables in this suspected catalog should likely be known variables.