Press Release
0.2 arcsec Stellar Image Profile
June 10, 1999
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Telescope: 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 |
Explanation:
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.