Equipment and Techniques
My equipment consists of the
following:
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At the scope
I have my scope permanently mounted so that a simple one star alignment is all that is required. The MX916 camera requires only a few minutes to cool to operating temperature, and this can be done while the rest of the equipment is prepared. As soon as it's dark enough, I "synchronize" on one of the LX200's alignment stars. I also align the finder and my ETX guidescope so that all three optical systems are centered on the same object. The AT1010 80mm scope can be mounted in the same Losmandy rings as the ETX.
I leave the camera attached to the scope. I normally use an f6.3 focal reducer for deep sky imaging and an f3.3 reducer can be used for even wider fields of view. Most of my integrations are 30-120 seconds. For longer exposures, when guiding is required, I use a Meade ETX 90mm Maksutov as a guide scope. This instrument is mounted on Losmandy rings/dovetail mount. For wide angle imaging I attach the CCD camera to the AT1010 scope or use it with a piggy-back mount and a telephoto lens.
I usually set the LX200 in the HiPrecision Pointing (HPP) mode. This causes the scope to slew to a nearby star (near the object to be imaged). While pointing at this bright star (always visible through the finder) the camera is placed in the "Find" mode. The star, which is usually out of focus, can then be centered on the CCD chip using the directional keys. I usually adjust the focus at this time to roughly bring the star to a point. Integrations of 250-500 msec are all that is required to image the star, so screen updates are acceptable.
Once the star is centered, I switch to the "Focus" mode and tweak the focus until the star is as small as possible. AstroArt and most other camera control programs display an ADU value or FWHM value to assist in achieving optimal focus. Once focus has been adjusted, I press the "GoTo" key on the LX200 to slew to the object of interest. Finding and centering are done just as for the nearby star, using a long enough integration to reveal the object (usually 5-15 seconds).
I then switch to "Image" mode (AstroArt) and set the time and number of images to be acquired. Sixty second integrations can be done unguided if polar alignment is good. Two to three minute integrations (or longer) are possible with precise polar alignment. Four minute integrations or longer can be achieved with short focal lengths (AT1010 or telephoto lenses). For guided images I use a 9mm illuminated reticle in the ETX guidescope. The MX916 also supports STAR2000, which allows image acquisition while guiding on a star in the field of view. Dark frames are then taken by covering the scope and making a series of integrations with the times equal to or longer than the images. I usually try to median combine 16 dark frames, bracketing the actual image integrations.
I use a home made
lightbox to produce flat field images. The basic idea is to make exposures of the sky
using the same optical path as for the image to be processed. This method offers a simple
and reproducible approach to flat fielding - imaging a field that roughly saturates 50-75%
of the range of the camera. Flats can also be made quickly at dusk or dawn, using a simple
diffuser over the aperture of the scope. Since the MX916 uses a 16-bit converter (65536
for the dynamic range) about 32000 gives an acceptable flat. I usually adjust the exposure
to achieve the 32000 count. I take multiple flats, and then average or median combine
them. I store the individual flats and darks and process each image separately
later.
Images are stored on the observatory computer until the end of the imaging session. Then I copy them to my desktop via the local network. During imaging runs I use Microsoft Netmeeting to control the scope and camera from inside the house. This is especially useful when the temperature is very cold. It also allows me to do other work during long imaging runs without being in the observatory.
Image processing 
The following steps are what I normally employ for processing raw images. I use one or more of several image processing packages:
Multi245, CB245, and QColor by Richard Berry; this suite of programs is designed specifically for CookBook camera files but can also accept standard FITS format files. Multi245 is a track and stack program, while CB245 allows more advanced image manipulation (filterings, shaping, etc.). QColor supports RGB, LRGB, CMY and WCMY color processing. AIP4Win is a new package from Richard Berry and James Burnell and offers all of the components of the earlier programs with a Windows interface. I use AIP almost exclusively for basic image processing. MaximDL is also a very powerful program for processing monochrome and color images.
I process flat frames first making sure that an appropriate flat exists for each image (color, etc.). A Master Flat is produced by subtracting a dark frame of the same integration time from the individual flats and then median combining. I usually take dark frames of longer duration than the images and then scale them using the functions in AIP4Win or in MaximDL.
The raw images then have the dark frame subtracted and are divided by the flat field. After this processing raw images are "registered" and then median combined or averaged. The resulting image is then adjusted by filtering as necessary to produce the best visualization. Several images may also be combined using a mosaic function. Images are then exported to one of several programs for final processing and labeling (Corel Photopaint, Adobe Photoshop).
Color images are handled similarly. White light (W) images are made with no filtration or just an infrared blocker (IR). Cyan (C), magenta (M), yellow (Y) or Red (R), Green (G), Blue (B) images are made through the appropriate filter with the IR blocker in place. These color components are registered using AIP4Win. The RGB components are then combined and balanced. The effects of atmospheric extinction and atmospheric coloration are removed and the final image produced.
