A Comprehensive Correction of the Gaia DR3 XP Spectra

Abstract

By combining spectra from the CALSPEC and NGSL, as well as spectroscopic data from the LAMOST Data Release 7 (DR7), we have analyzed and corrected the systematic errors of the Gaia DR3 BP/RP (XP) spectra. The errors depend on the normalized spectral energy distribution (simplified by two independent “colors”) and G magnitude. Our corrections are applicable in the range of approximately −0.5 < BP − RP < 2, 3 < G < 17.5, and E(B − V) < 0.8. To validate our correction, we conduct independent tests by comparisons with the MILES and LEMONY spectra. The results demonstrate that the systematic errors of BP − RP and G have been effectively corrected, especially in the near-ultraviolet. The consistency between the corrected Gaia XP spectra and the MILES and LEMONY is better than 2% in the wavelength range of 336–400 nm and 1% in redder wavelengths. A global absolute calibration is also carried out by comparing the synthetic Gaia photometry from the corrected XP spectra with the corrected Gaia DR3 photometry. Our study opens up new possibilities for using XP spectra in many fields. A Python package is publicly available to do the corrections (doi:10.12149/101375 or https://github.com/HiromonGON/GaiaXPcorrection).

A Star-based Method for the Precise Flux Calibration of the Chinese Space Station Telescope Slitless Spectroscopic Survey

“…Gaia DR3 provides high-quality low-resolution (R ∼ 50) BP and RP spectra covering the wavelength range 3300-10500 Å. After a comprehensive correction for systematic errors in the flux calibration (Huang et al 2024), it provides an alternative data set for the UaRA-net to deliver a large number of fluxstandard stars.…”

S-PLUS: Photometric Recalibration with the Stellar Color Regression Method and an Improved Gaia XP Synthetic Photometry Method

“…The XP spectra cover a wavelength range of 336 to 1020 nm, and have undergone precise internal calibrations (Carrasco et al 2021;De Angeli et al 2023), as well as external calibrations (Montegriffo et al 2023). However, it is crucial to note that Gaia XP spectra are subject to systematic errors that depend on magnitude, color, and extinction, especially at wavelengths below 400 nm (see Montegriffo et al 2023;Huang et al 2024). A comprehensive set of corrections, based on reference spectra from CALSPEC and NGSL, have been provided by Huang et al (2024).…”

“…However, it is crucial to note that Gaia XP spectra are subject to systematic errors that depend on magnitude, color, and extinction, especially at wavelengths below 400 nm (see Montegriffo et al 2023;Huang et al 2024). A comprehensive set of corrections, based on reference spectra from CALSPEC and NGSL, have been provided by Huang et al (2024). In this paper, the term "corrected Gaia XP spectra" refers to the Gaia XP spectra as rectified by Huang et al (2024).…”

“…The XP spectra cover wavelengths from 336 to 1020 nm, and have undergone precise internal (Carrasco et al 2021;De Angeli et al 2023) and external calibrations (Montegriffo et al 2023). Unfortunately, the Gaia XP spectra exhibit systematic errors that depend on magnitude and color, particularly at wavelengths below 400 nm (see, e.g., Montegriffo et al 2023;Huang et al 2024).…”

“…More recently, comprehensive corrections to the Gaia XP spectra have been provided by Huang et al (2024), utilizing spectra from CALSPEC (Bohlin et al 2014;Bohlin & Lockwood 2022) and Hubble's Next Generation Spectral Library (NGSL; Koleva & Vazdekis 2012). In this process, the spectroscopy-based SCR method (Yuan et al 2015) was employed as well.…”