This is far, far from the best Pinwheel Galaxy image that you can find online. The image here is a stack of seven x 120 seconds subs, and thus a total exposure of fourteen minutes. I would estimate that at least an hour's worth of exposures are required to really bring out the finer details and beautiful structure of M101.All the image processing details are as with the previous image. Here's some of the technical data on the scope and camera from June 19.
The camera was thermoeletrically cooled to 20d Celsius below ambient (which was about 60% of the total cooling capacity available). I used the CCDOPS (SBIG camera control software) autodark feature. Apparently the initial dark frame is subsequently used for calibration of the light frames. That's a huge time saving feature.
The image scale using the StellarVue115 with the .8 TeleVue focal reducer is 2.37 arcseconds/pixel with a 47x63 arcminutes field of view. (I've cropped the M101 image.)
I also tried the CCDOPS track and accumulate feature on two different objects. Unfortunately this feature did not produce usable images, as the "accumulated" stack lacked precise alignment. Over an hour worth of imaging time was wasted on this dead end. After consulting the manual (on the following day), I discovered that track and accumulate is recommended only for relatively short exposures.
Max
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