The Astronomical Plate Digitization at SHAO

TL;DR

The paper addresses preserving century-long historical plate data by developing dedicated digitizers at SHAO. It describes two digitizer generations—the line-scanning first (2013–2017) and the air-bearing, block-scanning second (2019–2024)—achieving sub-micrometer positioning and scan times on the order of a few minutes per plate, with ~8×10^8 pixels per plate. International collaboration under IAU guidelines and with the University of Chile expands digitization efforts and data sharing, while science applications include astrometric and photometric calibrations across plates from multiple facilities and Gaia DR2-based reductions of Pallas and Vesta with ~0.1–0.2 arcsec accuracy. The work preserves irreplaceable observational heritage and provides high-precision data for long-term astronomical studies and broader scientific use via the China Virtual Observatory.

Abstract

The digitization of historical astronomical plates is essential for preserving century-long observational data. This work presents the development and application of the specialized digitizers at the Shanghai Astronomical Observatory (SHAO), including technical details, international collaborations, and scientific applications on the plates.

Figures (10)

• Figure 1: Examples of astronomical plates taken by SHAO.
• Figure 2: The first digitizer at SHAO.
• Figure 3: New generations of plate digitizers at SHAO.
• Figure 4: The first new digitizer at SHAO.
• Figure 5: Example of star images on a plate digitized by the new generation SHAO's machine. At this digitized plate of 300$\times$300 mm$^2$ we have $\sim$0.8 billion pixels.