Press Release

0.2 arcsec Stellar Image Profile

June 10, 1999

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Subaru Telescope (Effective diameter 8.2m)/ Cassegrain Focus
Instrument: CISCO (Cooled Infrared Spectrograph and Camera for OHS)
Filter: Near Infrared K'-band (2.15 micron)
Date of Observation: May 7, 1999 UT
Exposure Time: 5 sec

The figure shows a cross-cut profile of the light intensity distribution of a star observed with the infrared camera CISCO mounted on the Subaru Telescope. The light intensity or brightness of the stellar image is plotted along the vertical axis against angle along the horizontal axis. The stellar image is wonderfully sharp, with a full-size at half its maximum intensity (or "FWHM") of only 0.198 arcsec. This level of resolution is only rarely achieved by ground-based optical/infrared telescopes without real-time, active correction of the image such as with adaptive optics (AO) or "tip-tilt" technology. Being in space where there is no atmospheric turbulence, Hubble Space Telescope has been obtaining images with an angular resolution better than 0.2 arcsec. Subaru Telescope demonstrated its high performance last January with images of 0.3 arcsec angular resolution. Subaru Telescope has achieved the angular resolution of 0.2 arcsec after elaborate adjustment of the primary mirror active optics system. Because the primary mirror of Subaru Telescope is much larger than the 2.4 m primary of Hubble Space Telescope, Subaru's sharp imaging capability will allow us to see deeper into the Universe than Hubble can.

It should be noted that the excellent quality of the Mauna Kea site is a major contributing factor in achieving such high image quality.



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