COSMOS-Web: Comprehensive Data Reduction for Wide-area JWST NIRCam Imaging

Abstract We present the data reduction methodology used for the COSMOS-Web survey JWST NIRCam data. Covering 0.54 deg 2 with four broadband filters (F115W, F150W, F277W, F444W) and a total exposure time of approximately 270 hr, COSMOS-Web represents the largest contiguous field surveyed during JWST Cycle 1, posing unique data reduction challenges due to its extensive scale. By combining the official JWST Calibration Pipeline with custom improvements for noise removal, background subtraction, and astrometric alignment, we achieve high-fidelity science-ready mosaics. We detail the systematic approach employed in the three stages of the JWST Calibration Pipeline. The data, collected in three epochs from 2023 January to 2024 January, encompass 152 visits and have been processed into 20 mosaic tiles to optimize computational efficiency and data processing. The final data products achieve 5 σ depths of 26.7–28.3 AB mag in 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 15 apertures. The processed and calibrated datasets are made available to the public.

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Publication Details

Journal
The Astrophysical Journal
Published
2026-03-03
DOI
https://doi.org/10.3847/1538-4357/ae3aa1
Primary Topic
Galaxies: Formation, Evolution, Phenomena
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article
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article

COSMOS-Web: Comprehensive Data Reduction for Wide-area JWST NIRCam Imaging

M. Wetzstein, Steven L. Gillman, Jorge A. Zavala, E. Berman et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

COSMOS-Web: Comprehensive Data Reduction for Wide-area JWST NIRCam Imaging

M. Wetzstein, Steven L. Gillman, Jorge A. Zavala, E. Berman, G. Magdis, Santosh M. Harish, Lilan Yang, Rafael C. Arango-Toro, Andrew Battisti, Micaela B. Bagley, Armin Rest, Sune Toft, J. Kartaltepe, C. Casey, Jed McKinney, H. Akins, Louise Paquereau, Nicole E. Drakos, Carter Flayhart, M. Hirschmann, Nima Chartab, Marko Shuntov, Ghassem Gozaliasl, Si-Yue Yu, Henry Joy McCracken, Jacqueline E. McCleary, Brant E. Robertson, Maximilien Franco, David B. Sanders, Daizhong Liu, Diana Scognamiglio, Arianna S. Long, Anton M. Koekemoer, Bahram Mobasher, Andreas L. Faisst, Jason Rhodes
article en

Abstract

Abstract We present the data reduction methodology used for the COSMOS-Web survey JWST NIRCam data. Covering 0.54 deg 2 with four broadband filters (F115W, F150W, F277W, F444W) and a total exposure time of approximately 270 hr, COSMOS-Web represents the largest contiguous field surveyed during JWST Cycle 1, posing unique data reduction challenges due to its extensive scale. By combining the official JWST Calibration Pipeline with custom improvements for noise removal, background subtraction, and astrometric alignment, we achieve high-fidelity science-ready mosaics. We detail the systematic approach employed in the three stages of the JWST Calibration Pipeline. The data, collected in three epochs from 2023 January to 2024 January, encompass 152 visits and have been processed into 20 mosaic tiles to optimize computational efficiency and data processing. The final data products achieve 5 σ depths of 26.7–28.3 AB mag in 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 15 apertures. The processed and calibrated datasets are made available to the public.

The Astrophysical JournalVol. 999(2)
University of California, Riverside (US), Australian National University (AU), California Institute of Technology (US), University of Copenhagen (DK), Northeastern University (US), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), University of Hawaii System (US), Jet Propulsion Laboratory (US), University of Helsinki (FI), Johns Hopkins University (US), University of California, Santa Barbara (US), Rochester Institute of Technology (US), Kavli Institute for the Physics and Mathematics of the Universe (JP), The University of Western Australia (AU), University of California, Santa Cruz (US), Durham University (GB), Carnegie Institution for Science (US), Chinese Academy of Sciences (CN), University of Washington (US), Université Paris Cité (FR), Aix-Marseille Université (FR), University of Massachusetts Amherst (US), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), Trieste Astronomical Observatory (IT), Institut d'Astrophysique de Paris (FR), Purple Mountain Observatory (CN), University of Hawaii at Hilo (US), Sorbonne Université (FR), Astrophysique, Instrumentation et Modélisation (FR), ASTRO-3D (AU), Université Bourgogne Franche-Comté (FR), Carnegie Observatories (US), CEA Paris-Saclay (FR), ARC Centre of Excellence for All-sky Astrophysics (AU), International Centre for Radio Astronomy Research (AU), Infrared Processing and Analysis Center (US), Osservatorio di Astrofisica e Scienza dello Spazio, École Polytechnique Fédérale de Lausanne (CH), Seattle University (US), The University of Tokyo (JP), The University of Texas at Austin (US), Technical University of Denmark (DK), Aalto University (FI)
Openalex Percentile: Top 37%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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