The positions of asteroid (433) Eros in the Gaia system based on the results of the analysis of scans of Pulkovo astronegatives taken in 1900 and 1930

In recent years, A2 parameter determinations became available for many asteroids due to astrometric measurements’ quantity and quality improvement. It is well known that the A2 parameter is associated with the influence of the Yarkovsky drift of asteroid orbits. The mentioned A2 determinations can be performed using a 50-year (or even less) time series of positional data for relatively small asteroids (with a size of about hundreds of meters). These calculations meet many difficulties for larger bodies (more than 10 kilometers). Logically, a relatively long time series with 100-year coverage leads to a significantly good effect manifestation. The (433) Eros asteroid is an illustrative case in the considered context. It has a long history of observations (since the 1890s). Unfortunately, the (O-C) dispersion for old observations reaches several arc seconds. Therefore, A2 value estimation for this body is complicated. Digitization of the corresponding old photographic plates and remeasurements of the asteroid positions are required. We present the results of the remeasurements of the Pulkovo photographic plates containing (433) Eros images. These astronegatives were taken with the Pulkovo Normal Astrograph in 1900 and 1930. Digitization was performed with the NAROO digitization center (Paris Observatory). A total of 18 asteroid positions were obtained at the accuracy level of 0.1 - 0.3 arcsec. The absolute values of (O − C)α and (O − C)δ do not exceed 0.5 arcsec relative to the NASA/Horizons ephemerides.