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Grasslands : The Messier
Objects in Color |
Color Images
The initial color images of the Messier Objects were obtained
with the 24-inch f/5 reflector at the Grasslands Observatory
from 1998 to early 2000. They were taken with an
Apogee AP7 CCD
camera. The Apogee AP7 contains a SITe 24 micron 512 x 512 CCD
chip that has excellent quantum efficiency throughout the
visible spectrum and into the near-infrared portion of the
spectrum. Since late 2000, color images of the Messier Objects
were taken with a
Finger Lakes
Instrumentation Dream Machine CCD camera. Dream Machine
images have now completely replaced the older AP7 images,
because the Dream Machine has a larger field of view, and
upgrades to the observatory drive system and focus system permit
much longer exposures with better results.
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AP7 CCD camera |
Dream Machine CCD Camera |
The AP7 images were used for
Sky and
Telescope's Messier Objects in Color Poster. Because the
images have the same relative exposures for each object type and
the same camera orientation and image size, they can be used to
compare one Messier object with another. For more details on our
imaging techniques see
Tri-Color CCD Imaging.
The exposures for the Dream Machine CCD camera are varied
ranging from 15-30 seconds for R, V, and B filter images
combined with 30 seconds Open images for bright clusters to 2-4
minute exposures for R, V, B filter images combined with 5-10
minute exposures for Open images for faint nebulae and galaxies.
In late 2007 a Quantum
Scientific Imaging (QSI) 532 CCD was acquired with an LRGB
filter set as well as a hydrogen alpha filter all residing in
the QSI 532 internal color wheel. The QSI 532 CCD has a
Kodak KAF-3200ME 2184 x 1472 chip with 6.8 micron pixels.
This camera can give very high resolution images with the
24-inch telescope, but guiding is critical, and 2x2 binning is
sometimes used for imaging. Typical exposures for black
and white pictures are 5-minute single exposures or three to ten
5-minute exposures median combined. For color imaging, the
black and white exposures are combined with 5 minute or longer
exposures through red, green, and blue, or hydrogen alpha
filters.
Recent equipment upgrades also include an 8-inch f/4 Meade LXD55
Schmidt-Newtonian telescope which has been mounted onto the side
of the 24-inch telescope. Imaging through the 8-inch telescope
is done with a Canon 20da digital camera back or the
QSI 532 CCD camera. The Canon 20da and the QSI 532 can
also be used with a Takahashi Epsilon 180 Astrograph
which is sometimes mounted on
the 24-inch telescope. Moreover, in early January 2007 a
Celestron C-14 with exquisite optics was permanently mounted
inside of the observatory building. This
telescope is used for visual observing and web cam imaging of
the Moon and Planets.
tbh 18 April 2010
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