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40"
Dream Telescope & Facility |
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The optical designer that Dream chose to create the
Prime Focus Corrector (PFC) on the 40" Dream PFTelescope
has created such correctors for telescopes as large as 8m. |
One of the largest correctors (the lens itself) that
the optical designer has done is 1.36m in diameter. |
The designer has created PFC's, Cassegrain correctors
and reducers, plus he has done the current design of LSST. The
latter is a 8.4m f1.25 (system f-ratio) telescope that employs
three mirrors and a three lens corrector. He has designed correctors
for 0.9m, 3.5m, 4.0m, 4.2m, etc.. |
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The 40" Dream PFT will be the world's largest
primary focus field, at 4.84 deg². |
The current design for this corrector will use a 382mm
clear aperture first element of silica. The illumination at the
extreme corners of the 95mm x 95mm CCD chip will be greater than
93%. |
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The telescope structure's declination attachment point
is facing down, near the lower/mid center of the structure. |
The primary mirror covers (carbon fiber) are also
shown in the rendering to the left, in the open position. The
prime focus corrector resides inside a baffle. The telscope will
be parked at a zero zenith angle, thus reducing dust
buildup on the prime focus corrector. |
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The carbon
fiber telescope, with all components shown to the right,
will weigh less than 500 lbs. This is less than 1/4 a conventional
telescope. |
A conventional 1m/40" telescope's primary mirror
alone can weigh 500-600 lbs. |
The use of a cellular
primary mirror and carbon fiber skinned sandwich
core structure and sub components allow this telescope to be
lighter, stiffer and track
ambient temperatures far better than other telescopes. The dome's
design was also based around sound thermal
features that help to produce the highest Delivered Image
Quality (DIQ). |
If the DIQ can be reduced from a FWHM of 1.25 to 0.85
arc seconds, exposure times can be cut in half to reach the same
magnitude: 28 versus 14 minutes to reach mag 25 with a s/n=3
in r'. |
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The comparison to the left shows the 40" Dream
above the 0.4m (16") Dream
Astrograph for scale. |
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To learn more about
The Madawaska Highlands Observatory, please visit their web
site. |
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Be sure to view the CAD
animation . |
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