TY - JOUR
T1 - Absolute Calibration. III. Improved Absolute Calibration for the Visible through the Mid-infrared
AU - Rieke, G. H.
AU - Engelke, Charles
AU - Su, Kate
AU - Casagrande, Luca
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - We propose Sirius as an improved zero-point-defining star and calibrate its spectrum to an accuracy of ∼0.6% in both the visible and infrared. This result is based on a newly derived independent calibration in the visible of similar accuracy to the previous standard one, with which it is combined. We use a large variety of approaches in the infrared to reach about three times smaller error than for previous absolute calibrations. The results in the two wavelength regimes are in agreement, providing a consistent link from the visible throughout the near- and mid-infrared. The Sirius-based zero-point at 5557.5 Å (in vacuum) is 13.436 ± 0.081 × 10−12 W cm−2 μm−1, based on the improved value for Vega of 3.473 ± 0.018 × 10−12 W cm−2 μm−1 and the measured magnitude difference between the two stars. At 2.1603 μm, the zero-point is 4.225 ± 0.025 × 10−14 W cm−2 μm−1 taking Sirius at a magnitude of −1.395. A jackknife analysis indicates that there are no serious systematic errors in these results. We consider selection of secondary standards that can extend the calibration over the sky. Despite more than a century in this role, normal A-stars are not suitable, although Am and Ap stars may be. G-stars older than ∼1 Gyr are good candidates if accurate temperatures can be measured. White dwarfs are suitable from the visible through the near-infrared, but their properties are unexplored at the necessary level at the longer infrared wavelengths, and for most facilities they are too faint there. Finally, as a further test of the calibration, we demonstrate an upgraded infrared flux method to determine accurate stellar diameters from K-band photometry.
AB - We propose Sirius as an improved zero-point-defining star and calibrate its spectrum to an accuracy of ∼0.6% in both the visible and infrared. This result is based on a newly derived independent calibration in the visible of similar accuracy to the previous standard one, with which it is combined. We use a large variety of approaches in the infrared to reach about three times smaller error than for previous absolute calibrations. The results in the two wavelength regimes are in agreement, providing a consistent link from the visible throughout the near- and mid-infrared. The Sirius-based zero-point at 5557.5 Å (in vacuum) is 13.436 ± 0.081 × 10−12 W cm−2 μm−1, based on the improved value for Vega of 3.473 ± 0.018 × 10−12 W cm−2 μm−1 and the measured magnitude difference between the two stars. At 2.1603 μm, the zero-point is 4.225 ± 0.025 × 10−14 W cm−2 μm−1 taking Sirius at a magnitude of −1.395. A jackknife analysis indicates that there are no serious systematic errors in these results. We consider selection of secondary standards that can extend the calibration over the sky. Despite more than a century in this role, normal A-stars are not suitable, although Am and Ap stars may be. G-stars older than ∼1 Gyr are good candidates if accurate temperatures can be measured. White dwarfs are suitable from the visible through the near-infrared, but their properties are unexplored at the necessary level at the longer infrared wavelengths, and for most facilities they are too faint there. Finally, as a further test of the calibration, we demonstrate an upgraded infrared flux method to determine accurate stellar diameters from K-band photometry.
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U2 - 10.3847/1538-3881/ac9f1b
DO - 10.3847/1538-3881/ac9f1b
M3 - Article
AN - SCOPUS:85148043776
SN - 0004-6256
VL - 165
JO - Astronomical Journal
JF - Astronomical Journal
IS - 3
M1 - 99
ER -