The Parallax Zero-point of Gaia Early Data Release 3 from LAMOST Primary Red Clump Stars

We present an independent examination of the parallax zero-point of the Third Gaia Early Data Release (hereafter EDR3), using the LAMOST primary red clump (PRC) stellar sample. A median parallax offset of around 26 mu as, slightly larger than that found by examination of distant quasars, is found for both the five- and six-parameter solutions in EDR3, based on samples of over 63,000 and 2000 PRC stars, respectively. Similar to the previous investigation of Lindegren et al., to which we compare our results, the parallax zero-point exhibits clear dependencies on the G magnitudes, colors, and positions of the objects. Based on our analysis, the zero-point of the revised parallax can be reduced to a few mu as, and some significant patterns, e.g., discontinuities with stellar magnitude, can be properly removed. However, relatively large offsets (>10 mu as) are still found for the revised parallaxes over different positions on the sky.

Automated summary

This study independently examines the parallax zero-point of the Third Gaia Early Data Release using the LAMOST primary red clump stellar sample, revealing slight differences compared to previous studies on distant quasars. The analysis shows clear dependencies of the zero-point on the magnitudes, colors, and positions of the stars, with potential for reducing the zero-point and removing significant patterns, but still finding relatively large offsets in revised parallaxes at different sky positions.