A reevaluation of the 2MASS zero points using CALSPEC spectrophotometry complemented with Gaia Data Release 2 parallaxes

TL;DR

This study recalibrates the zero points of the 2MASS near-infrared survey using CALSPEC spectrophotometry and Gaia DR2 parallaxes, leading to more accurate photometric calibration.

Contribution

It provides revised zero points for 2MASS JHK bands based on spectrophotometry and Gaia data, resolving previous discrepancies.

Findings

Revised 2MASS zero points: J=-0.025, H=0.004, K=-0.015 mag.

New zero points are more accurate than previous estimates.

Validation with FGK dwarfs confirms improved calibration.

Abstract

CONTEXT. 2MASS is the reference survey in the NIR part of the spectrum given its whole-sky coverage, large dynamic range, and proven calibration uniformity. However, previous studies disagree in the value of the zero points (ZPs) for its three bands JHK at the hundredth of a magnitude level. The disagreement should become more noticeable now that Gaia provides whole-sky optical photometry calibrated below that level. AIMS. We want to establish the value of the 2MASS ZPs based on NICMOS/HST spectrophotometry of the CALSPEC standard stars and test it with the help of Gaia DR2 parallaxes. METHODS. We have computed the synthetic JHK photometry for a sample of stars using the HST CALSPEC spectroscopic standards and compared it with their 2MASS magnitudes to evaluate the ZPs. We have tested our results by analysing a sample of FGK dwarfs with excellent 2MASS photometry and accurate Gaia DR2 parallaxes.} RESULTS. The Vega ZPs for 2MASS J, H, and K are found to be -0.025$\pm$0.005 mag, 0.004$\pm$0.005 mag, and -0.015$\pm$0.005 mag, respectively. The analysis of the FGK sample indicates that the new ZPs are more accurate than previous ones.