As regular readers of both mine and Dan’s blogs will know, using the 20″ has been a constant struggle to produce untrailed images. The approach taken has been to keep exposures as short as possible and be prepared to throw away a high percentage that show bad tracking.
With the new servos and controller we decided to press the club’s old SBIG STV into service again as a guider using the supplied 100mm focal length e-finder scope. Despite the disparity in focal lengths between this and the main instrument the results from initial testing are impressive.
This being an Alt-Az mount we chose IC 405 as a suitable subject as it was below 40 degrees in the East, with a bright star in the nebula that could be used for guiding. After an initial test exposure we increased the time to 300 seconds and reduced the ISO to 800 and took 6 frames. The first was unusable due to instability in altitude but the remaining 5 frames showed remarkably little trailing. Dan’s result is here.
IC 405 is a combination of an emission and reflection nebula in the constellation of Auriga.
