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3towers Observatory Operations


Equipment and Operations:
TritowerA.jpg (103480 bytes) 3towerspanorama.jpg (35299 bytes)

The 3towers Observatory consists of a 10 foot Home-Dome with a 12-inch Meade LX-200 computerized telescope. For most imaging the telescope is used with an f/6.3 focal reducer that gives a system f/ratio of 6.5 with an effective focal length of 80 inches (~ 2000mm). The Dome is motorized, and it uses Technical Innovation's Dome-Trak to automatically slew the dome so the shutter opening follows the telescope position. The telescope was originally used for visual observing. It is now mainly used for CCD imaging. An Apogee AP7 CCD camera is linked to a Pentium 600 computer system running MaxIM DLL/CCD, The Sky, and MegaStar. During an imaging session, the telescope's computer control finds and center objects. A Technical Innovations Robo-Focus is used for obtaining a sharp focus. The Robo-Focus gives a precise digital reading that is reproducible from night to night. It remembers its digital position when it is turned off and on. Tri-color CCD imaging is performed using an ISIS FW1 filter wheel containing Photometric Red (R), Green (V), Blue (B), Infrared (I), and Clear filters, and Clear filters. The CCD images are compared with comparable fields in The Sky and MegaStar to make certain the correct object is being imaged. The field of view of the AP7 camera is approximately 22 minutes of arc, but most images are cropped slightly to give effective fields of view of 18-20 minutes. The CCD is mounted on the telescope so that all images are oriented with the North at the top and the West to the right. Possible findings on a CCD image not shown on the charts in MegaStar or The Sky are checked with the Palomar Sky Survey images in The Real Sky. Zip and Jaz drives were originally used to back up important data files and provide an easy means of transporting data between the observatory and the in-house computer. The observatory computer is now networked to the in-house computer, and the 3towers Observatory can be remotely controlled from inside my house (see The Semi-Automation (Remote Control) of the 3towers Observatory). Image processing is usually performed on the in-house computer using a variety of programs, including MaxIM DLL, Mira, Corel Photo-Paint 9, and Photoshop 6.0 (see discussion on Tri-Color CCD Imaging in the Grassland Image Gallery).

An f/3.3 focal reducer was added to the observatory system in early March 2001. This permits ultra-wide field imaging giving an effective focal length of 40 inches (~ 1000mm) with a field of view of nearly 40 minutes of arc. However, there is considerable image distortion produced by this system. Any stray light harms the images, and all the images require exquisite flat field correction to be useable. Because of these constraints, this short focal length system is only used on rare occasions.
 
m51color.jpg (15480 bytes) M51 (R-60sec; V-60sec; B-90sec) 12-inch LX 200
with f/3.3 focal reducer
tritowerC.jpg (107292 bytes) Nighttime views of the Meade LX 200,
Apogee CCD, and computer system
tritowerB.jpg (145809 bytes) An Orion dewshield is very effective at keeping stray light
from the computer screen off the telescope optics
end paragraph
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