These 3towers Observatory images were originally taken on a 12-inch LX 200
telescope using a focal reducer at f/6.5 with an Apogee KX260
CCD camera or an Apogee AP7 CCD camera running under MaxIm DL/CCD.
The black and white images vary from single 30-second exposures
to images produced by adding sixty one-minute exposures together
using a median routine in Mira or MaxIm DL/CCD.
The color images were taken with the Apogee AP7 CCD and an ISIS FW1
Filter Wheel containing Red
(R), Green (V), Blue (B), Infrared (I), and Clear Photometeric filters. The exposures varied
from R = 30-seconds, V = 30-seconds, B = 40-seconds for bright
objects to Red = five to ten 60-second exposures added together,
Green (V) = five to ten 60-second exposures added together, Blue =
eight to twenty 60-second exposures added together for fainter
objects. For very faint objects, even longer exposure sequences
were used for each color. For some objects, clear exposures were
also taken and added to the exposures through the photometric
filters to produce a final color image.
Since March 2012, the 3towers observatory has contained a Celestron NexStar 11 GPS telescope which has special coatings for enhanced transmission of light. The C-11 is used with a Starizona HypeStar focal reducer and a Starlight XPress SXVR-H9C single shot color camera or a Canon 60Da camera for most imaging applications. An Orion Star Shoot AutoGuider on an Orion 50 mm Guide Scope helps with longer exposures. The observatory computer is networked to the in-house computer, and image files can be transferred to the in-house computer after they are downloaded from the CCD camers.
The C-11 HyperStar combination has a focal length of 560 mm with the f/2 HyperStar. The field of view of the Starlight Xpress SXVR-H9C is 56.6 x 41.1 arcminutes, and the field of view of the Canon 60Da is 139 x 91.5 arcminutes. This permits ultra-wide field imaging, particularly with the Canon 60Da. Stray light from inside and outside the observatory including light from the nearby 3 towers is blocked from the telescope imaging system by a long semi-permanent dew shield which extends beyond the length of the HyperStar CCD combination.
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