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.
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.
