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The Mid-Infrared Multi-field Imager for gaZing at the UnKnown Universe (MIMIZUKU) is the first-generation (mid-)infrared instrument on the TAO telescope that enables imaging and low-resolution spectroscopic observations in a wavelength range of 1-38 microns. The wide wavelength coverage is achieved by having three optical channels, NIR, MIR-S, and MIR-L, covering 1-5.3, 7-26, and 24-38 microns, respectively. MIMIZUKU has a unique opto-mechanical system called a "field stacker" that enables simultaneous observations of target and reference objects within a distance of less than 25 arcmin. This feature improves the accuracy and reliability of photometric and spectroscopic data. The overview of TAO/MIMIZUKU is also summarized in the fact sheet linked below.
For the entrance window of the MIMIZUKU optics, KBr window and diamond window are available. This semester, a diamond window is equipped. The diamond window has absorption bands in the L and M bands, and the sensitivity in these bands is not good.
The NIR channel has a HAWAII-1RG (HgCdTe 1k-format) array with a cut-off wavelength of 5.3 microns and covers 1-5.3 microns. The atmospheric transmittance and the wavelength coverage of each observing mode are shown below.
 |  |
| Available modes and atmospheric transmittance smoothed with a Gaussian profile with an FWHM of 0.002 um-1. | Atmospheric transmittance covered by the 2.7-um spectroscopy mode smoothed with a Gaussian profile with an FWHM of 0.00056 um-1. |
| Wavelength Coverage | 1-5.3 microns | |
|---|---|---|
| Detector | 1k-format HgCdTe array (Teledyne HAWAII-1RG 5.3um-cutoff) | |
| Pixel Scale | 0.069"/pix | 18 um/pix |
| Field of View | 1.2' x 1.2' | w/o Field Stacker |
| 36" x 1.2' x 2 fields | w/ Field Stacker | |
| Final F number | 8.76 | |
| Spatial Resolution | almost seeing-limited | for details, see here. |
| Imaging Filters | J, H, Ks, L', and M' | |
| Spectroscopy | KL and LM bands with R~200 | |
| 2.7-um band with R~660 | ||
| Slit | 0.96" x 36" | wider region (2.7" width) also available. |
The MIR-S channel has an Aquarius array (Si:As 1k-format) array and covers 7-26 microns. The atmospheric transmittance and the wavelength coverage of each observing mode are shown below.
 |  |
| N-band modes and atmospheric transmittance smoothed with a Gaussian profile with an FWHM of 0.0005 um-1. | Same as the left figure but for the Q band. |
| Wavelength Coverage | 7-26 microns | |
|---|---|---|
| Detector | 1k-format Si:As IBC array (Raytheon Aquarius) | |
| Pixel Scale | 0.11"/pix | 30 um/pix |
| Field of View | 2.0' x 2.0' | w/o Field Stacker |
| 59" x 2.0' x 2 fields | w/ Field Stacker | |
| Final F number | 8.76 | |
| Spatial Resolution | almost diffraction-limited | for details, see here. |
| Imaging Filters | 7.7, 9.8, 11.5, 13.1, 16.7, 17.9, 20.9, and 24.5 um | |
| Spectroscopy | N band with R~170 | |
| Q band with R~110 | ||
| Slit | 0.58" x 57" x 2 slits | |
| 1.1" x 57" x 2 slits |
The MIR-L channel has a 128px-format Si:Sb array and covers 24-38 microns.
 |
| Modes in 30-um band and the atmospheric transmittance. |
| Wavelength Coverage | 24-38 microns | |
|---|---|---|
| Detector | 128-format Si:Sb BIB array (DRS MF-128) | |
| Pixel Scale | 0.24"/pix | 75 um/pix |
| Field of View | 31" x 31" | w/o Field Stacker |
| 15" x 31' x 2 fields | w/ Field Stacker | |
| Final F number | 10.5 | |
| Spatial Resolution | almost diffraction-limited | for details, see here. |
| Imaging Filters | 32 and 37 um | |
| Spectroscopy | N/A | |
| Slit | N/A |
Currently, not available.
 |
| Schematic view of the Field Stacker system placed on the MIMIZUKU chamber that houses the optics. |
The Field Stacker (FS) is a special opto-mechanical system installed on MIMIZUKU. It has two movable pick-off mirrors and one combining mirror that introduce lights from two different sky fields to the optics. This mechanism allows us to observe two objects in the two sky fields simultaneously. If you observe your science target and a telluric standard simultaneously using FS, the accuracy and reliability of atmospheric correction might be improved by canceling out the temporal variation of the atmospheric absorption. This feature is expected to be useful to perform long-term monitoring observations, and actually, its usefulness was confirmed in the engineering observations performed at the Subaru telescope (c.f., Michifuji et al. 2020, Kamizuka et al. 2020). Usefulness at the TAO site will be examined in future. In observations, you can choose to use it or not.
