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Grasslands Observatory Image Gallery


Coma Cluster (Abel 1656; NGC4889)
Black & White
Color

The early (1996-2001) Black & White and Color images displayed in this web page were obtained with an Apogee AP7 camera (or its predecessor, the HPC-1 camera) running under MaxIm DL/CCD (Cyanogen Productions). The only image processing used for the majority of the images was conversion of raw CCD FITS format images (after appropriate bias, dark, and flat field processing) into Red (R), Green (V), Blue (B), and Infrared (I) or Black & White grayscale Tiff images in Mira (Axiom Research), MaxIm DL/CCD, or CCDSoft. For color imaging, the R, V, B, and, in some cases the I, grayscale images were then combined in Adobe PhotoShop to produce color Tiff and JPEG images.

The R, V, B, and I filters are STANDARD JOHNSON-COUSINS PHOTOMETRIC FILTERS. Therefore, there is usually excellent color rendition that accurately reflects the color emission of the objects imaged, and there is no need to worry about infrared leakage through the filters. Moreover, the separate R, V, B, and I images contain potential valuable professional photometric data. All raw data is saved, because the Observatory's images have the potential for later scientific study.

The Grasslands Observatory now uses a large format CCD camera for much of its imaging at the f/5 focus of the 24-inch telescope. In March 2001, a Finger Lakes Instrumentation Dream Machine CCD camera was installed at the observatory. This camera has a high quantum efficiency SITe 1024 x 1024 twenty-four micron CCD chip. It provides a nearly 28 minute field of view.  The Dream Machine is used in operation with a Finger Lakes Instrumentation CFW-1 Color Filter Wheel and an Optec TCF temperature compensating focuser. The filter wheel contains Photometric R, V, and B filters and also has an Open slot (O). 

Exposures typically range from R = 1 minute, Green (V) = 1.5 minutes, B = 2 minutes, and O = 1-2 minutes to R = 4 minutes, Green (V) = 6 minutes, B = 8 minutes, and O = 5-20 minutes for the Dream Machine CCD camera. Short exposures are used for bright clusters, and long exposures are used for faint galaxies and nebulae. Most color imaging is performed using a Luminance technique with Open or Clear exposures used for the Luminance (L) part of the color composition.

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 or 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
 

Camea Close-up.jpg (47952 bytes)
Dream Machine CCD Camera combined with a Finger Lakes CFW-1 Color Filter Wheel
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Tri-Color CCD Imaging at the Grasslands Observatory | Table - Making a Color CCD Image
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