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.
|
colorSmall.jpg)
