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First Data Release of the Hyper Suprime-Cam Subaru Strategic Program

Hiroaki Aihara, Robert Armstrong, Steven Bickerton, James Bosch, Jean Coupon, Hisanori Furusawa, Yusuke Hayashi, Hiroyuki Ikeda, Yukiko Kamata, Hiroshi Karoji, Satoshi Kawanomoto, Michitaro Koike, Yutaka Komiyama, Robert H. Lupton, Sogo Mineo, Hironao Miyatake, Satoshi Miyazaki, Tomoki Morokuma, Yoshiyuki Obuchi, Yukie Oishi, Yuki Okura, Paul A. Price, Tadafumi Takata, Manobu M. Tanaka, Masayuki Tanaka, Yoko Tanaka, Tomohisa Uchida, Fumihiro Uraguchi, Yousuke Utsumi, Shiang-Yu Wang, Yoshihiko Yamada, Hitomi Yamanoi, Naoki Yasuda, Nobuo Arimoto, Masashi Chiba, Francois Finet, Hiroki Fujimori, Seiji Fujimoto, Junko Furusawa, Tomotsugu Goto, Andy Goulding, James E. Gunn, Yuichi Harikane, Takashi Hattori, Masao Hayashi, Krzysztof G. Helminiak, Ryo Higuchi, Chiaki Hikage, Paul T. P. Ho, Bau-Ching Hsieh, Kuiyun Huang, Song Huang, Masatoshi Imanishi, Ikuru Iwata, Anton T. Jaelani, Hung-Yu Jian, Nobunari Kashikawa, Nobuhiko Katayama, Takashi Kojima, Akira Konno, Shintaro Koshida, Haruka Kusakabe, Alexie Leauthaud, C. -H. Lee, Lihwai Lin, Yen-Ting Lin, Rachel Mandelbaum, Yoshiki Matsuoka, Elinor Medezinski, Shoken Miyama, Rieko Momose, Anupreeta More, Surhud More, Shiro Mukae, Ryoma Murata, Hitoshi Murayama, Tohru Nagao, Fumiaki Nakata, Hiroko Niikura, Atsushi J. Nishizawa, Masamune Oguri, Nobuhiro Okabe, Yoshiaki Ono, Masato Onodera, Masafusa Onoue, Masami Ouchi, Tae-Soo Pyo, Takatoshi Shibuya, Kazuhiro Shimasaku, Melanie Simet, Joshua Speagle, David N. Spergel, Michael A. Strauss, Yuma Sugahara, Naoshi Sugiyama, Yasushi Suto, Nao Suzuki, Philip J. Tait, Masahiro Takada, Tsuyoshi Terai, Yoshiki Toba, Edwin L. Turner, Hisakazu Uchiyama, Keiichi Umetsu, Yuji Urata, Tomonori Usuda, Sherry Yeh, Suraphong Yuma

TL;DR

The paper presents the first public data release (DR1) of the HSC-SSP, delivering 61.5 nights of imaging across Wide (≈108 deg^2), Deep (≈26 deg^2), and UltraDeep (≈4 deg^2) layers in grizy (with some narrow bands), reaching i-band depths around 26.4–27.0 mag (5σ point sources). It details the end-to-end data-processing pipeline (hscPipe) that produces calibrated images and catalogs via single-visit detrending/calibration, multi-visit mosaicking/coadding, and multi-band measurements, plus afterburner photometry and a VVDS reprocessing step. Value-added products, including photometric redshifts and public spectroscopic redshifts, are released alongside the imaging data, with thorough validation showing ~1–2% photometric precision and internal ~10 mas and external ~40 mas astrometric accuracy. The DR1 release also documents data quality assessments, known issues, and the data-access infrastructure, and outlines a plan for future incremental and major releases that will include fully validated shear measurements and deeper data products. Overall, this release establishes a rich, well-characterized public dataset with broad potential for cosmology, galaxy evolution, and multi-wavelength cross-correlation studies, while signaling ongoing improvements in PSF modeling, deblending, and sky subtraction for future releases.

Abstract

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope and it started in March 2014. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7 years of observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and ~27.0 mag, respectively (5sigma for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF photometry (rms) both internally and externally (against Pan-STARRS1), and ~10 mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online. The data release website is https://hsc-release.mtk.nao.ac.jp/.

First Data Release of the Hyper Suprime-Cam Subaru Strategic Program

TL;DR

The paper presents the first public data release (DR1) of the HSC-SSP, delivering 61.5 nights of imaging across Wide (≈108 deg^2), Deep (≈26 deg^2), and UltraDeep (≈4 deg^2) layers in grizy (with some narrow bands), reaching i-band depths around 26.4–27.0 mag (5σ point sources). It details the end-to-end data-processing pipeline (hscPipe) that produces calibrated images and catalogs via single-visit detrending/calibration, multi-visit mosaicking/coadding, and multi-band measurements, plus afterburner photometry and a VVDS reprocessing step. Value-added products, including photometric redshifts and public spectroscopic redshifts, are released alongside the imaging data, with thorough validation showing ~1–2% photometric precision and internal ~10 mas and external ~40 mas astrometric accuracy. The DR1 release also documents data quality assessments, known issues, and the data-access infrastructure, and outlines a plan for future incremental and major releases that will include fully validated shear measurements and deeper data products. Overall, this release establishes a rich, well-characterized public dataset with broad potential for cosmology, galaxy evolution, and multi-wavelength cross-correlation studies, while signaling ongoing improvements in PSF modeling, deblending, and sky subtraction for future releases.

Abstract

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope and it started in March 2014. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7 years of observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and ~27.0 mag, respectively (5sigma for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF photometry (rms) both internally and externally (against Pan-STARRS1), and ~10 mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online. The data release website is https://hsc-release.mtk.nao.ac.jp/.

Paper Structure

This paper contains 55 sections, 2 equations, 20 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Overview of the Release
  3. The release
  4. Survey Progress
  5. Previous internal releases
  6. Data Processing
  7. Terminology
  8. Data screening
  9. Single-visit processing -- Detrending and Calibration
  10. Multi-visit processing -- mosaic, joint calibration, and coadding
  11. Multi-band measurements
  12. Afterburner
  13. VVDS reprocessing
  14. COSMOS Wide-depth stacks
  15. The release data
  16. ...and 40 more sections

Figures (20)

  • Figure 1: The area covered in this release shown in equatorial coordinates. The blue, green and red areas show the Wide, Deep, and UltraDeep layers, respectively included in the data release. The boxes indicate the approximate boundaries of the three disjoint regions that will make up the final Wide survey. Note that AEGIS is a calibration field observed at the Wide depth and is not formally a part of the Wide survey. The Galactic extinction map from 1998ApJ...500..525S is also shown as a grayscale.
  • Figure 2: Allocated number of nights and number of visits acquired. The top panel shows the cumulative number of visits for the Wide layer obtained as a function of the number of observing nights. The dashed lines indicate the average numbers of visits required to complete the survey in 300 nights in the $gr$ (bottom line) and $izy$ filters (top line), respectively. The bottom panel shows the cumulative number of visits as a function of time.
  • Figure 3: Seeing distribution of individual visits for each filter. The seeing measured by the on-site system is used and only visits with sky transparency greater than 0.3 are plotted here (note that only data with transparency $>0.3$ are used in the main processing; see Section \ref{['sec:data_processing']}). The numbers and arrows show the median seeing. The vertical dashed lines indicate the seeing threshold (1.3 arcsec) below which visits are used in the processing. Note that seeing shown is as measured and is not corrected for airmass.
  • Figure 4: Distribution of elevation at which visits are taken for each filter. The top ticks show the corresponding airmass. The numbers and arrows show the median elevation in each band.
  • Figure 5: Schematic view of the flow of the processing and data products generated at each stage.
  • ...and 15 more figures