Maximilien Franco, C. Casey, Anton M. Koekemoer, Daizhong Liu, Micaela B. Bagley, Henry Joy McCracken, J. Kartaltepe, H. Akins, Olivier Ilbert, Marko Shuntov, Santosh M. Harish, Brant E. Robertson, Rafael C. Arango-Toro, Andrew Battisti, Nima Chartab, Nicole E. Drakos, Andreas L. Faisst, Carter Flayhart, Ghassem Gozaliasl, M. Hirschmann, Richard Massey, Jason Rhodes, Zahra Sattari, Diana Scognamiglio, John R. Weaver, Lilan Yang, Jorge A. Zavala, E. Berman, Fabrizio Gentile, Steven L. Gillman, Arianna S. Long, G. Magdis, Jacqueline E. McCleary, Jed McKinney, Bahram Mobasher, Louise Paquereau, Armin Rest, David B. Sanders, Sune Toft, Si-Yue Yu
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 . ″ 15 apertures. The processed and calibrated datasets are made available to the public.