Spitzer IRAC observations of JWST calibration stars

Abstract

We present infrared photometry of all 36 potential JWST calibrators for which there is archival Spitzer IRAC data. This photometry can then be used to inform stellar models necessary to provide absolute calibration for all JWST instruments. We describe in detail the steps necessary to measure IRAC photometry from archive retrieval to photometric corrections. To validate our photometry we examine the distribution of uncertainties from all detections in all four IRAC channels as well as compare the photometry and its uncertainties to those from models, ALLWISE, and the literature. 75% of our detections have standard deviations per star of all observations within each channel of less than three percent. The median standard deviations are 1.2, 1.3, 1.1, and 1.9% in [3.6] - [8.0] respectively. We find less than 8% standard deviations in differences of our photometry with ALLWISE, and excellent agreement with literature values (less than 3% difference) lending credence to our measured fluxes. JWST is poised to do ground-breaking science, and accurate calibration and cross-calibration with other missions will be part of the underpinnings of that science.

16 pages, 5 figures, AJ accepted

References in corpus (4)

• The James Webb Space Telescope
• Techniques and Review of Absolute Flux Calibration from the Ultraviolet to the Mid-Infrared
• The 4.5 $\mu$m full-orbit phase curve of the hot Jupiter HD 209458b
• Photometry using the Infrared Array Camera on the Spitzer Space Telescope

Cited by in corpus (6)

• Sub-Millimetre Galaxies with Webb: Near-Infrared Counterparts and Multi-wavelength Morphology
• How do Spitzer IRAC Fluxes Compare to HST CALSPEC
• Infrared Absolute Calibration I: Comparison of Sirius with Fainter Calibration Stars
• Searching for TESS Photometric Variability of Possible JWST Spectrophotometric Standard Stars
• Tying Spitzer's IRS Calibration to IRAC: Observations of IRS Standard Stars
• The James Webb Space Telescope Absolute Flux Calibration. I. Program Design and Calibrator Stars