Drizzle on the Fly

The Milky Way Galaxy

Drizzle on the Fly

Drizzle on the Fly is recommended. This allows you to see what a post processing result may look like, worst case. Generally you can improve on the image quality in post processing, but the on the fly processing will help you to make field adjustments.

Be sure to first pick your object of interest as the center point in the Envisage software on the DSI live image tab, or if nebulous, pick a star as close as possible to the center point of the object. Then choose another star as far away from the center point, but not too far away that the star goes out of view. If it does go out of view, the drizzle will probably start to smear. It is not necessary to stop the imaging, especially if the drizzle results up to that point were good. This second point is used to track the rotation of the sky verses the observation point (polar mounts). Both stars are critical to getting a good on the fly drizzle image.

The biggest problem I had with picking stars was that I was picking bad spots on the CCD. Bad spots do not move from image to image. So when tracking is sloppy, the bad spots appear to move in relation to the star field being imaged. So, selecting a bad spot for tracking results in a drizzle or combine is almost useless - streaks of stars and other bad spots. However, just because you picked the wrong "stars", doesn't mean the images are useless. On the contrary, they could be very processable. Hence the reason we save RAW, or at least Uncombined, images.

When you are setting the drizzle up, be sure to name the object in such a way that you will recognize the observation. Envisage software uses the type of combine method as the default object name. You'll want to log everything, oops, it's dark outside. You wont remember, so maybe that pocket voice recorder is not a bad idea - something else to drop in the dark and step on.

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