Goal of the Workshop

The medium-band (MB) filters for Subaru Hyper Suprime-Cam (HSC) consist of 16 bands with bandwidths of Δλ ~ 20–50 nm, covering λ ~ 400–1000 nm. The combination of the HSC MB filters, HSC’s wide field of view, and the light-collecting power of Subaru’s 8.2 m primary mirror will provide a unique dataset: deep, wide-field, R ~ 20 hyperspectral imaging data. In February 2026, the first medium-band quadrant (MBQ) saw first light, marking the start of the HSC-MB survey, HSC-Niji. The remaining three MBQs are currently under fabrication.

This workshop aims to explore and discuss the science cases that will be enabled by HSC-Niji. HSC-Niji is a Japan-led MB survey that aims to secure Subaru nights not only through Japanese Subaru time, but also through Subaru access available to other communities, including the University of Hawaii (UH), Keck, and Gemini. The first phase of the survey, HSC-Niji Blue, will be carried out with MBQ1, which consists of four MB filters spanning 400–500 nm. With HSC-Niji Blue, we plan to conduct a WIDE survey covering the HSC-SSP WIDE fields down to ~25.5 mag, a DEEP survey covering EDF-N down to ~26.5 mag, and a UDEEP survey covering COSMOS down to 27.2 mag. The second phase of HSC-Niji is planned to begin in the S28B semester and will conduct a survey using all 16 MB filters.

The baseline science cases include the detection of Lyman-break galaxies (LBGs) and Lyman-alpha emitters (LAEs), the identification of protoclusters, and studies of AGN, the star formation histories of galaxies across cosmic time, and Galactic archaeology. HSC-Niji can also provide calibration data that will be crucial for ongoing and upcoming imaging surveys, including Euclid, Roman, Rubin, and JWST.

This workshop seeks to engage the broader community in identifying additional compelling science cases for HSC-Niji. A key goal is to incorporate these ideas into the observing strategy, survey design, and collaborative framework. We also welcome ideas for other observational programs, such as those conducted through the Subaru Open Use Normal Program, that leverage the unique capabilities of the HSC-MB system.

logistics

Science Cases (click on the logos for details)

Filter Specification (Click on the figure for details, real measured data is available upon request)

Registration (in person or online participation)

Program

Poster Presentations

List of Participants

Venue

Nagoya University, Higashiyama Campus, ES635 (6th floor of the ES building, C2-4 in the campus map)

Co-sponsors

International Leading Research, JSPS Grant No. JP22K21349 "Comprehensive Understanding of the formation history of structures in the Universe"

Kobayashi Maskawa Institute, Nagoya University

Contact

Do not hesitate to ask LOC any questions.