MUSUBI (MegaCam Ultra-deep Survey: U∗-band Imaging) Data for the COSMOS and SXDS Fields

Wei Hao Wang, Sebastien Foucaud, Bau Ching Hsieh, Hung Yu Jian, Lihwai Lin, Yen Ting Lin, Jean Coupon, Yasuhiro Hashimoto, Masami Ouchi, Kazuhiro Shimasaku, Youichi Ohyama, Keiichi Umetsu, Shiang Yu Wang, Tzu Ching Chang

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The Subaru Hyper Suprime-Cam (HSC) Strategic Survey is the latest-generation multiband optical imaging survey for galaxy evolution and structure formation. The "Ultra-deep"component of the HSC survey provides grizy broadband images over 1/43.4 deg2 to detection limits of 1/426-28 AB, along with narrowband images, in the COSMOS and SXDS fields. These images provide an unprecedented combination of depths and area coverage, for studies of galaxies up to z ∼7. However, the lack of coverage at <4000 Å implies an incomplete sampling of the rest-frame UV at z 2 3, which is critically needed for understanding the buildup of stellar mass in later cosmic time. We conducted a multiyear CFHT u∗-band imaging campaign in the two HSC Ultra-deep fields with CFHT MegaCam. By including shallower archival data, we reached 5σ depths of u∗ = 28.1 and 28.4 (AB) at the centers of the COSMOS and SXDS fields, respectively, and u∗ = 27.7 and 27.8 in the central 1 deg2 fields. The image quality is 3 0.″90, fairly good for the u∗ band. Both the photometric and astrometric quality of our data are excellent. We show that the combination of our u∗-band and HSC data can lead to high-quality photometric redshifts at z = 0-3, and robust measurements of rest-frame UV on galaxies at 0.4 < z < 0.6 for distinguishing green-valley galaxies from star-forming and quiescent galaxies. We publicly release our reduced u∗-band images and reference catalogs, which can be used readily for scientific studies.

Original languageEnglish
Article number54
JournalAstrophysical Journal, Supplement Series
Issue number2
Publication statusPublished - 2022 Jun 1

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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