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

TL;DR

This paper introduces an improved calibration method for S-PLUS photometry using Gaia XP spectra and stellar color regression, significantly reducing systematic errors and enhancing zero-point precision for wide-field survey data.

Contribution

It presents a novel combined calibration approach leveraging Gaia XP spectra and stellar color regression, achieving higher accuracy and precision in photometric calibration.

Findings

Detected position-dependent systematic errors up to 23 mmag in S-PLUS DR4.

Achieved 1-6 mmag zero-point offset accuracy with combined methods.

Improved calibration precision by two- to three-fold.

Abstract

We present a comprehensive re-calibration of medium- and broad-band photometry from the Southern Photometric Local Universe Survey (S-PLUS) by leveraging two approaches: an improved Gaia XP Synthetic Photometry (XPSP) method with corrected Gaia XP spectra, the Stellar Color Regression (SCR) method with corrected Gaia EDR3 photometric data and spectroscopic data from LAMOST DR7. Through the use of millions of stars as standards per band, we demonstrate the existence of position-dependent systematic errors, up to 23 mmag for the Main Survey region, in the S-PLUS DR4 photometric data. A comparison between the XPSP and SCR methods reveals minor differences in zero-point offsets, typically within the range of 1 to 6 mmag, indicating the accuracy of the re-calibration, and a two- to three-fold improvement in the zero-point precision. During this process, we also verified and corrected for the systematic errors related to CCD position. The corrected S-PLUS DR4 photometric data will provide a solid data foundation for conducting scientific research that relies on high-calibration precision. Our results underscore the power of the XPSP method in combination with the SCR method, showcasing their effectiveness in enhancing calibration precision for wide-field surveys when combined with Gaia photometry and XP spectra, to be applied for other S-PLUS sub-surveys.