Report 4: Resumption of Open Use Observations at Cassegrain Focus

(September 13, 2011 Hawaii Time)

Three of Subaru Telescope’s four foci are now operational. Subaru Telescope resumed open use operation of the Cassegrain focus on August 26th, following the resumption of observations at the two Nasmyth foci on July 22nd. Two of the three instruments for the Cassegrain focus, the Cooled Mid-Infrared Camera and Spectrometer (COMICS) and the imaging mode of the Multi-Object Infrared Camera and Spectrograph (MOIRCS), are available for open use; neither was affected by the July 2nd coolant leak. A third instrument, the Faint Object Camera and Spectrograph (FOCAS) as well as the auxiliary subsystem at the Cassegrain focus have been removed and are being repaired.

Notes: The instruments and auxiliary system at Cassegrain focus.

Subaru Telescope offers three observational instruments as well as an auxiliary system for enhancing observations at the Cassegrain focus.

- COMICS (Cooled Mid-Infrared Camera and Spectrometer)
The thin, dry air over the 13,796' mountain of Mauna Kea gives the Subaru Telescope excellent conditions for detecting mid-infrared light from astronomical objects. COMICS is a camera and spectrograph that can take advantage of this unique observational setting. Its applications include investigation of how individual stars in our own galaxy form; how large-scale star formation in other galaxies takes place; and how interstellar dust, the raw material of planets, comes into being. COMICS does not require the Cassegrain auxiliary system for most of its observations.

- MOIRCS (Multi-Object Infrared Camera and Spectrograph)
MOIRCS, a wide-field near-infrared instrument using eight megapixel detectors, has the widest field of view of all infrared instruments among 8-meter class telescopes. It can obtain spectra of multiple astronomical objects at the same time, dramatically increasing its observational efficiency. Imaging observations with MOIRCS's camera do not usually require the use of the Cassegrain auxiliary system.

- FOCAS (Faint Object Camera and Spectrograph)
FOCAS is Subaru's workhorse instrument for high-sensitivity optical observations. Its multi-slit system allows it to capture spectra of up to 100 objects simultaneously. This powerful capability facilitates measurement of distances to faint galaxies near the edge of the Universe.

- Auxiliary System
The auxiliary system accompanies each focal station of the Subaru Telescope. It includes the auto-guider, the Shack-Hartmann camera, the image rotator for Nasmyth foci, the instrument rotator for primary and Cassegrain foci, and the atmospheric dispersion corrector (ADC).

Subaru Telescope and Its Instruments at Cassegrain foci.

Figure:Instruments offered at the Cassegrain focus of the Subaru Telescope. COMICS and the imaging mode of MOIRCS are available. FOCAS and spectroscopy with MOIRCS are in the process of restoration.

National Astronomical Observatory of Japan

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