Correction to the Photometric Colors of Gaia Early Data Release 3

Abstract

In this work, we use the spectroscopy-based stellar color regression method with ∼0.7 million common stars between LAMOST DR7 and Gaia EDR3 to acquire color corrections in G - G_RP and G_BP - G_RP. A sub-millimagnitude precision is achieved. Our results demonstrate that improvements in the calibration process of the EDR3 have removed the color term in G_BP - G_RP and eliminated the discontinuity caused by the changes of instrument configurations to a great extent. However, modest systematic trends with G magnitude are still detected. The corresponding color correction terms as a function of G are provided for 9.5 mag < G < 17.5 mag and compared with other determinations. We conclude that the corrections given in this work are particularly suited for cases where the color-color investigations are required, while for color-magnitude investigations other corrections may be better owing to systematics with reddening. Possible applications of our results are discussed.