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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 4.01, 5.0, 5.5, or 6.0 to produce color Tiff and JPEG images.

The R, V, B, and I filters used for color imaging are STANDARD JOHNSON-COUSINS PHOTOMETRIC FILTERS. Therefore, there is 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. For the immediate future, all raw data is being saved, because the Observatory's images have the potential for later scientific study.

Typical early exposures for Black & White images were 30sec to 120sec for bright objects and 120sec to 600sec for faint objects. Typical exposures for Tri-color CCD imaging were R: 2-4 minutes, V: 2-4 minutes, B: 4-6 minutes, and I: 2-4 minutes. Bright objects, such as open clusters, will have even shorter relative exposures, and faint objects, such as galaxy clusters or a faint supernova, will have a somewhat longer relative exposure through the various filters. For some objects, clear exposures were also taken and added to the exposures through the photometric filters to produce a final color image.

The Grasslands Observatory now uses a large format CCD camera. 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 on the 24-inch f/5 reflector at the Grasslands Observatory. 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). This instrument combination is used for most of the imaging at the Grasslands Observatory.

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.

Recent equipment upgrades 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 now done with a Canon 20da digital camera back.  In addition, a Takahashi Epsilon 180 Astrograph is available for mounting 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. 
 
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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