Comparison of Gaia BP/RP spectra with LDS (Low Dispersion Spectroscopy) photographic sky surveys

Blue (BP) and Red (RP) Photometer low-resolution spectral data is one of the exciting new products in the third data release of ESA satellite Gaia (Gaia DR3)1. The Gaia "photometric mode" RP/BP generates ultra -low-dispersion prism spectra of celestial sources. The LDS (Low-Dispersion Spectroscopy) astrophysics was evolved and performed at numerous observa-tories (many in US) between ca 1909 and 1980. Mostly LDS with Schmidt telescopes was performed (plates with objective prism). These data were used in the past for various projects e.g. QSO, emission line and Halpha surveys, star classifications, etc. but little used after 1980. My estimate is that there are more than 100 million LDS star spectra in these databases. I will discuss their astrophysical scientific potential in recent astrophysics. I will show that these data can be used e.g. for the redshift estimation and study of High z Universe)