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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.
 
AP7.jpg (43861 bytes) Camea Close-up.jpg (47952 bytes)
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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