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Hyper Suprime-Cam (HSC)

  Read-out anomaly in CCD 021 (1_34)

CCD 021 (1_34) has suffered read-out failure over the entire surface since April 25th, 2025 HST (see the report for details). It has been decided to keep this CCD disabled from the beginning of HSC S25A July run to prevent occurrence of noises on the neighbor CCDs. See also the CCD arrangement diagram.

  Information for S26A applicants

  • HSC operation in S26A

    There will be at most two (2) or three (3) HSC observing runs in the S26A semester.


  • Change in the Phase 2 submission period for HSC Queue-mode proposals

    Applicants are requested to submit the Phase 2 form by the same deadline as Service program proposals.
    See HSC Queue Mode webpage for details.


  • Change in the submission deadline for proposals of HSC Queue-mode Filler programs

    Filler proposals for HSC Queue mode must be submitted by the same deadline as Normal/Intensive program proposals.
    See HSC Queue Mode webpage for details.


  • New filter: MBQ1

    The MBQ1 (Medium Band Quadrant) filter is newly opened for open-use observations in S26A.
    See HSC Filter Information page for details.


  • Requested time for Queue-mode proposals

    Applicants for HSC Queue-mode observation must include various overheads to the requested time. Total requested time for observing plan should be calculated using the Overhead and Required Time Calculator. Please clearly indicate how it is calculated in the "Observing Method and Technical Details" section of the application form, for example,

        HSC-g:    240 sec x 20 shots
    HSC-i2:   200 sec x 40 shots + 30 sec x 4 shots
    Total on-source time:   3.59 hours
    Total required time:    4.89 hours

    If no quantitative justification is explicitly shown for the time request, a low evaluation value will be given in the technical assessment process. According to the decision of Subaru Advisory Committee (SAC), 30% bad weather factor will be considered for time allocation of the HSC Queue-mode programs in order to increase the observation completion rate by ensuring sufficient observation time. To keep the limitation of the maximum nights, the requested time in the HSC Queue mode should not exceed 3.5 nights for each Normal program and 28 nights for each Intensive program.


  • Exposure time calculation

    Required signal-to-noise ratio and exposure time should be estimated by using HSC ETC and mentioned in the "Observing Method and Technical Details" section of the application form. Be sure to clearly specify all input values for the calculation such as the filter, magnitude, point/extended source, seeing, aperture size, transparency, and moon phase/distance condition, so that reviewers can reproduce the results. If no reasonable justification is not provided for the requested exposure times, a low evaluation value will be given in the technical assessment process.


  • Weather factor for Classical-mode programs

    For a Normal Program in the Classical mode, please do NOT explicitly include the weather factor when justifying the number of nights requested. For an Intensive Program in the Classical mode, applicants may take into account the weather factor of 0.7 when justifying the number of nights requested. See this document for the details.


  • HSC Queue-mode proposals with other instruments

    If you request to use HSC Queue mode and other instruments in a program, please be sure to clearly describe the observing constraints such as acceptable seeing, transparency, and moon phase/distance in the "Observing Method and Technical Details" section of the application form. See this page for the details.


  • SMOKA check

    Please make sure to check SMOKA and confirm whether or not your targets have already been observed by HSC in the past. "HSC Search" is useful for searching HSC archival data. Use "Circular" search region (RA and DEC) with a radius of 45–90 arcmin. If there are archival data obtained in the field covering your target with HSC and the filters required for your program but no reasonable justification is not provided in the "Public Data Archive of Subaru" section of the application form, a low evaluation value will be given in the technical assessment process.


  • Filter set

    All applicants must explicitly describe the filters they intend to use in the "Instrument Requirements" section of the application form, where the desired set as well as the minimum acceptable set should be clearly specified.


  • Default observation mode

    Queue mode is the default observing mode for the Normal, Intensive, and Filler programs (see the detail information at the "HSC Queue Mode Webpage"). Applicants wishing a Classical-mode observation with HSC have to describe why the Classical mode is preferred to the Queue mode in "Scheduling Requirements" section of the application form. Without any convincing reason, the observation mode may be changed from Classical to Queue. Note that a proposal requesting the NB387, NB391, or NB395 filter with autoguiding must be submitted as a Classical-mode program.


  • "No-Additional-Target" policy

    Requesting additional targets for filling dead time (a.k.a. "Sukima time"), when there is no planned target on the night sky, is not allowed for any HSC observations. "Sukima time" will be exploited as effectively as possible depending on the situation (observing priority: (1) observations of standard stars, (2) Queue-mode observations for Grade A/B programs, (3) observing applicant's back-up targets, and (4) Queue-mode observations for Grade C and F [Filler] programs).


  • No service programs

    Service observations are not available for HSC.


  Last update: July 21, 2025

News

Introduction

The Hyper Suprime-Cam (HSC) is a gigantic mosaic CCD camera, which is attached at the prime focus of Subaru Telescope. The HSC uses 104 main science CCDs which cover 1.5-deg field-of-view in diameter with a pixel scale of 0.17 arcseconds, as well as 4 CCDs for auto guider and 8 CCDs for focus monitoring.

It takes about 30 min for changing filters (including a focus check). Before starting a filter exchange, it is necessary to move the telescope to the zenith and rotate the instrument rotator to the appropriate angle. We also have to close the cover of the primary mirror for safety operation.

When you consider developing a new HSC filter, please be sure to read the filter policy carefully and contact the Subaru Telescope (contact person: T. Terai terai_at_naoj.org) well before applying for funds. Also, please refer to the procedure to determine filters for each HSC run.

We ask for your understanding in advance that the obtained data of which proprietary period (18 months) has not yet expired may be used by Subaru staff without PI's permission for engineering purposes.

Instrument

Observation

Data Analysis and Archive

Tools

Image Quality

Investigation Reports

Problem Reports

Contact

Questions regarding HSC should be directed to Satoshi Miyazaki (satoshi_at_naoj.org) and Tsuyoshi Terai (terai_at_naoj.org).

Please note that all numbers on these pages are subject to change as the performance of HSC is better determined.

Last Update:  July 21, 2025