Report 3: Resumption of Open Use Observations

(July 27, 2011 Hawaii Time)

On the night of July 22nd Subaru Telescope resumed open use observations at Nasmyth foci. There are several instruments associated with the Nasmyth foci that were not affected by the leak and are available in the open use observations: The High Dispersion Spectrograph (HDS), the 188-element Adaptive Optics (AO188) system, the Infrared Camera and Spectrograph (IRCS), and the High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO).

Although the incident affected the telescope's primary mirror, water washing has been successful in restoring its surface and functionality. Coolant leaked inside the auxiliary equipment of the Subaru Prime Focus Camera (Suprime-Cam). Both Suprime-Cam and its auxiliary equipment have been removed from the primary focus for further inspection and restoration. No coolant is currently circulating at the top end of the telescope. Observations at Nasmyth foci use a secondary mirror located at the top end but do not require the use of coolant.

The instruments of the primary focus are being thoroughly inspected. They will resume operation after the implementation of corrective measures to prevent future incidents. Observations using the Cassegrain focus will resume once the affected areas are cleaned and tested.


- High Dispersion Spectrograph (HDS)
This instrument examines the visible light from an object by splitting it into highly dispersed spectral lines. It is used to study the chemical composition of first-born stars in galaxies or to reveal the presence of planetary systems by showing variations in the velocity of the stars.

- Adaptive Optics with 188 Elements (AO188)
The AO system sharpens a stellar image blurred by atmospheric turbulence; it does so by quickly changing the shape of a small mirror inserted into the optical path. This process allows for very high spatial resolution observations. It currently operates with either IRCS (Infrared Camera and Spectrograph) or HiCIAO.

- Infrared Camera and Spectrograph (IRCS)
This instrument enables imaging and spectroscopy in infrared wavelengths by utilizing the high spatial resolution and high sensitivity of AO188. It covers a wide range of observations that span from individual star/planet formation regions to areas of distant galaxies.

- High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO)
This instrument blocks infrared light from a bright object and enables the search for objects surrounding it. It is used to detect exoplanets, i.e., planets circling a star other than the Sun, or to study the structure of circumstellar disks around young stars.

Subaru Telescope and Its Instruments at Nasmyth foci.

Illustration: Subaru Telescope and Its Instruments at Nasmyth foci. Open use observations have resumed and are utilizing these instruments located at Nasmyth foci. The optical side utilizes HDS, while the IR side operates with AO188, IRCS, and HiCIAO.

National Astronomical Observatory of Japan

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