CEERS MIRI imaging : data reduction and quality assessment

Abstract

The Cosmic Evolution Early Release Science Survey (CEERS), targeting the Extended Groth Strip extragalactic field, is one of the James Webb Space Telescope Director’s Discretionary Early Release Science programs. To date, all observations have been executed and include NIRCam/MIRI imaging and NIRSpec/NIRCam spectroscopic exposures. Here we discuss the MIRI imaging, which includes eight pointings, four of which provide deep imaging with the bluer bands (F560W and F770W) and four of which provide contiguous wavelength coverage in F1000W, F1280W, F1500W, and F1800W, where two of these also include coverage in F770W and F2100W. We present a summary of the data, data quality, and data reduction. The data reduction is based on the JWST CALIBRATION PIPELINE combined with custom modifications and additional steps designed to enhance the output quality, including improvements in astrometry and the removal of detector artifacts. We estimate the image depth of the reduced mosaics and show that these generally agree with expectations from the Exposure Time Calculator.We compare the MIRI F560W and F770W flux densities for bright sources to measurements from Spitzer/IRAC Ch3 (5.8 μm) and Ch4 (8.0 μm), and we find that they agree with systematic differences of <0.1 mag. For the redder MIRI bands, we assess their quality by studying the spectral energy distributions (SEDs) of Galactic stars. The SEDs are consistent with the expected Rayleigh–Jeans law with a deviation of ∼0.03 mag, indicating that the MIRI colors are reliable. We also discuss all publicly released data products (images and source catalogs), which are available on the CEERS website (https://ceers.github.io/).