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First-light imaging with SCT

Peter Hill



Forecast for Thursday night suggested it would be clear and it certainly was, although the atmosphere was quite turbulent, also more water vapour about.
Took the opportunity to try imaging with newly acquired 9.25" SCT.
20:15, no alignment with HEQ5pro, just drove it round onto Jupiter using attached finder, which had kept its setting from previous evening when I had just tried out the SCT for visual viewing. Set mount into tracking mode and it held Jupiter for the rest of the evening.
Nothing exciting happening, except for occlusion of Io at 22:20(BST) , have to remember change to BST when checking event predictions which are in U.T. Centred image using 12.5mm illuminated reticule eyepiece and the put neximage5 camera into diagonal, out of focus image in centre of screen , quickly focussed with the Feather Touch focuser, but forgot how frustrating it is trying to get focus spot on manually, having to wait for vibration to die down, equally the turbulent atmospherics did not help. Image one shows turbulence in the Jovian atmosphere, particularly in the equatorial belts, also festoons linked  with the blue patches in the Equatorial zone.
In the eyepiece Jupiter and its 4 Galilean moons were all visible, with Io the closest and Callisto at the outer extreme of its orbit, could only be clearly seen with 40mm plossl, although Callisto could be picked out using averted vision  with 24mm on  Baader Hyperion zoom. This is shown in second image.
Io got gradually closer to Jupiter until it was occluded at 22:20(BST), see third and fourth images.
Tried x2 Barlow but just made the turbulence worse!, even more difficult to focus! Finished at 22:45
Images were typically taken at exp of 1/137", gain at 22 as .avi files at 20fps , typically 600 frames.
Registax 5.1 used to stack and manipulate wavelets Photoshop.6 for final tweaks.

Considering conditions were not ideal and it was manual focussing I was reasonably happy with results.Definitely getting electric focusser attachment for feather touch and will probably upgrade the finder (any suggestions?) as well as adding a Telrad. Will probably get a 2" visual back, which will take the 2" diagonal I have and I can then use the Antares 2" -1.25" twist lock adapter , which makes popping eyepieces and cameras in and out so much easier. Slight hint of dew on front plate at end so dew shield (possibly heated?) also required.
Another month and will be able to see what it will do with Saturn and Mars, both of which are unfortunately going to be low in the sky, making turbulence real problem.
Pete Hill

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