Issue |
A&A
Volume 616, August 2018
|
|
---|---|---|
Article Number | L7 | |
Number of page(s) | 4 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/201833918 | |
Published online | 17 August 2018 |
Letter to the Editor
A reevaluation of the 2MASS zero points using CALSPEC spectrophotometry complemented with Gaia Data Release 2 parallaxes
1
Centro de Astrobiología, CSIC-INTA, Campus ESAC Camino bajo del castillo s/n, 28 692 Villanueva de la Cañada, Spain
e-mail: jmaiz@cab.inta-csic.es
2
Departamento de Astrofísica y Física de la Atmósfera, Universidad Complutense de Madrid, 28 040 Madrid, Spain
Received:
20
July
2018
Accepted:
30
July
2018
Context. 2MASS is the reference survey in the near-infrared (NIR) part of the spectrum due to its whole-sky coverage, large dynamic range, and proven calibration uniformity. However, previous studies disagree on 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 analyzing 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 ± 0.005, 0.004 ± 0.005, and −0.015 ± 0.005 mag, respectively. The analysis of the FGK sample indicates that the new ZPs are more accurate than previous ones.
Key words: surveys / methods: data analysis / techniques: photometric
© ESO 2018
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