The Update for S17B Applicants


MOIRCS is in Regular Operation

    MOIRCS is going to be operated under "regular" status (not under Shared-risk policy) from S17B Semester.

    There is no planned work related to the MOIRCS Upgrade during S17B.

    Please carefully read the following MOIRCS webpages before you design your observing strategy. If you have any question, please do not hesitate to contact the MOIRCS primary support astronmer (see the bottom of the page).

For MOS Applicants

    When you apply the MOS observation, you must explicitly specify the required number of MOS masks (both for the Full and the Minimum Number of Nights) in the Section 16 (Instrument Requirement) of the application form. Please describe the justification for these numbers in Section 14 (Technical Justification). The UH proposals also must explicitly specify the required number of MOS masks in their proposals.

    The number of MOS mask will be fixed once it is assigned by TAC's critical reviewing. The request for backup MOS mask is basically not permitted. However, we may consider the use of backup masks, if there is a clear justification. If the use of the backup masks become crucial after your observation is approved, please send the request to the SA for reviewing within the observatory.

    Please note that the maximum number of MOS mask available for one contiguous observing period is 15.


    You will need the FITS file of your target fields for the MOS mask design. If you don't have any images for the design, you can request to take the images 2 to 4 months before your observations ("preimage observation"). If you request the preimage observation, please contact the support astronomer soon after your schedule is fixed. Please read the Pre-imaging Information Page for more detail.

Current Status of the MOIRCS Upgrade Project

Posted 2016-07-04

After the replacement of the detector to Hawaii2RG in late last year, we have completed some engineering observations for the chracterization by July 2016. The success of the first engineering observation was appeared in a Subaru Web Topic article.

We have confirmed that the new detectors and electronics provide a significant reduction in electronic noise in the data. The new detectors have 14 and 15 electrons respectively of read noise in a CDS frame, which is about a factor of 2 improvement compared with the old system. In multi-sampling exposures we confirmed that the readnoise reduces roughly proportional to the square-root of the multi-sampling number. However, the degree of reduction slows relatively quickly at the number of multi-sampling larger than 20, possibly due to the ambient noise. In fact, we see some streak pattern across the slow-read direction in dark frame.

The new detectors have a better sensitivity than the old one, especially in Y and J bands. The rise of the sensitivity is from a few % (red side) to 27% (blue side). Note that the quantity largely depends on how you treat the QE variation across the detector.

The new system offers the 32-channel readout (cf. old system was 4 channel), which offers faster readout speed than the old system. The measured overhead time during a data acquisition, however, is about 15 sec. This is somewhat longer than expected, and we are still working on this.

Latent and inter-channel cross talk is quite low in channel-1 detector, while some degree of recognizable latent is seen for channel-2 image. We thus recommend to put high-priority target on channel-1 side.

The radiation hit events observed after replacement of the new detector was completely suppressed by the installation of a new alpha-particle blocker window we have installed just after the last lens. A short report can be found here.

The spectroscopic performance was evaluated in April and May. Overall, the trend of the improvement is as expected from the imaging observation. The improvement of YJ band is quite impressive. Thanks to the reduced readout noise, we can reach the background-noise-limited performance in all grisms we have within reasonable amount of time. This has helped better subtraction of the sky, as we can keep the unit exposure time relatively short, This resulted in the better quality of the final spectra.

Future Plan

We are also planning to introduce the IFU spectroscopy function to MOIRCS, as well as the upgrade of the current MOS system. The date of the downtime is still TBD, though currently starting from early 2017, when MOIRCS might "hibernate" more than a year for possible SWIMS operation, is expected.

We will update the information via this website.


MOIRCS (Multi-Object InfraRed Camera and Spectrograph) provides wide-field imaging and long-slit/multi-object (MOS) spectroscopic capabilities in the 0.9 ~ 2.5 µm spectral range under the natural seeing condition. The 4'×7' field of view is covered by two 2048×2048 infrared detector arrays with the spatial resolution of 0.116 arcsec/pixel. The detector has been updated to the Hawaii2 RG in late 2015.

For the imaging mode, the standard MKO YJHKs filters as well as some narrow-band filters are available. See the Imaging Mode Page for more details.

The MOS performance of MOIRCS spectroscopy mode is the most notable feature of the instrument. Using the cooled aluminum slit masks, MOIRCS can acquire 40 ~ 60 object spectra simultaneously across 0.9~2.5 micron wavelength range. The low-resolution (R~500) and high-resolution (R~3000) grisms are available (the R1300 medium-resolution grism is also available but have some issues). See the Spectroscopy Page for more details. All MOS observers/applicants should carefully read the MOS observation pages.

Instrument and Detector

Imaging mode

Spectroscopy mode

Instrument Citation

Please cite the following papers when you refer MOIRCS in your publication.

"Multi-Object Infrared Camera and Spectrograph (MOIRCS) for the Subaru Telescope I. Imaging"
Suzuki, R. et al. Publications of the Astronomical Society of Japan, 2008, Vol.60, No.6, pp.1347--1362.
"MOIRCS: Multi-Object Infrared Camera and Spectrograph for SUBARU"
Ichikawa, T. et al. 2006, in Proc. of SPIE, Vol. 6269, 38

For the MOIRCS Upgrade 2015 works, you can refer these papers below.

"The NuMOIRCS Project: Detector Upgrade Overview and Early Commissioning Results"
Walawender, J. et al. 2016, Proc. of SPIE, in press.
"Detector Upgrade of Subaru's Multi-Object Infrared Camera and Spectrograph (MOIRCS)"
Fabricius, M. et al. 2016, Proc. of SPIE, in press.

MOIRCS Management Structure

  • Observation Support Astronomers
    • Primary: Dr. Ichi Tanaka (email: )
    • Secondary: Dr. Kentaro Aoki (email: )
  • Primary Instrument Operator / Documentation Responsible
    • Joshua Williams (email:
  • Data Distribution Resonsible
    • Tom Winegar and Computer Division (email:
  • Instrument Hardware and Software Resonsible
    • Koji Omata on behalf of Instrument Division (email:
* Please change _AT_ to @ for email address.

Note that any data on the pages are subject to change.

Dr. Ichi Tanaka (MOIRCS Support Astronomer: email )

Updated 2016-08-08

Copyright © 2000-2016 Subaru Telescope, NAOJ. All rights reserved.