The Update for S16B Applicants


Shared-risk Operation of MOIRCS

    Due to the MOIRCS Upgrade Project (nuMOIRCS Project: see below), MOIRCS is operated under the shared-risk policy during S16B Semester.

    We have successfully completed the first engineering observation (for imaging test) in December 2015. Basic imaging performance is updated based on the engineering data, and is now available in the Imaging Mode pages as well as the Detector Information page below.

    Though the measured spectroscopic performance under new system is not available yet, we expect the overall performance to be better: we have roughly 10% to 40% higher sensitivity (red to blue, respectively) and much lower readnoise (1/2 ~ 1/3 of the old system) now. Just to be conservative, please use the current performance for the observing time estimate (unless the improved performance is crucial). We expect you can enjoy the improved S/N of the data by the new system.

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. And also, please describe why you need the requested number in Section 14 (Technical Justification).

    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, unless it is critical to the goal of the science. If you need backup mask, please make a clear justification on Section 14.

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

Current Status of the MOIRCS Upgrade Project

Posted 2016-04-11

As was annouced already, we have executed the first engineering works since summer 2015. MOIRCS now has two Teledyne Hawaii2 RG detector arrays and new array control electronics (ASIC and SAM from Teledyne). After the laboratory testing, the first engineering observation was successfully done in Dec 26 and 27, 2015.

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.

The new detector also has a better sensitivity than the old one. Especially in Y and J bands, roughly ~40% rise of the sensitivity is measured from the observing data. For more detail, please refer the report of the first engineering observation.

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.

The instrument control system (ICS) software is also replaced to the new in-house system, i.e., the system that was made entirely by the staff at the Subaru Telescope.

The major issue we have had during the engineering work is the unexpected observation of the large-number of the radiation hit events by the new detector (example image is here: 20-sec dark image). After some investication, we conclude that the radiation source is the AR coating of the last lens which contains the radio-active Thorium which emits the alpha-particle radiation(*). The expected energy range of the decay particle explains the heavily saturated nature of the appearance.

In order to block the incoming raditation, we have decided to install a thin glass window in front of the detector. The high IR-throughput low-reflectivity window is now being manufactured by Asahi Bunkou Co., and we are going to install the window in this spring, before S16A observation starts. ⇒ New!! We have confirmed that the blocking window successfully eliminates all the particle events (2016-03-19).

The effect of the alpha-particle blocking window on the measured sensitivity should be minimal. After the installation of the window, we will measure the system throughput again, and will update the numbers in the homepage.

The remaining task need to be done is the confirmation of the MOS system function under new control software. We will execute the functional verification of the system soon before April.

    (*) We appreciate the IRTF staff for sharing their experience with us.

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.


    !!! Caution !!!
    Some information on the current website are still for the old system before 2016. Be careful when you refer the number etc. Sorry for any inconvenience.

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 Hawai-2 RG 2048×2048 infrared detector arrays with the spatial resolution of 0.116 arcsec/pixel.

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 aluminium slit masks, MOIRCS can acquire about 40 object spectra simultaneously across 0.9~2.5 micron wavelength range. Currently low-resolution (R~500), medium-resolution (R~1300), and high-resolution (R~3000) modes are available. 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

!! Note that much of the info here is still for OLD MOIRCS before 2016 !!

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

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
    • 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 2016-01-19

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