I collected data for this image for three consecutive nights in early August, though with quite variable sky conditions. Most of us in North America obviously have not had great skies for astrophotography this summer. Being downwind of the Great Lakes, I tend to have very poor transparency all summer anyway, and the smoke from the west has been intermittently swinging overhead in the jet stream to make matters worse.

I went for this emission nebula complex, NGC7822 and Ced-214, which was a new target for me. It is nice because, being so close to North equatorial pole, it is visible to me most of the year and I figured that I could always revisit any time as needed. In the end, I managed a whole lot of integration time on three consecutive nights, though with quite varying sky conditions. The first night was actually one of the best of this year so far - clear and transparent all night long. The second night was very hazy to the point where I had to carefully sift through the frames for the most useable ones; I am not sure if this was smoke moving into the area or just poor transparency (our humidity has been nearly 100% every night in the past couple months). The third night was in between. Thus, my effort for the week was one good set of data, one average set of data, and one relatively poor set of data.

In the end, I tested integration in various ways by stacking frames from each night individually, stacking the best two nights together, and stacking all three sets. Interestingly, the integration of all data seemed to have the best overall look in terms of background smoothness and sharpness in the various nebula features. Comparing the full integration to the one stacking only the two best nights convinced me that my poorest set of data didn't help sharpen things too much, but it didn't seem to hurt either.

I've also uploaded a Revision B that compares one single, un-processed frame from each night taken at roughly the same time. I simply used a rough auto-stretch of the first night frame in APP and then applied that same setting to the other samples. Telescope and camera parameters are all identical, so the drastic difference in contrast is a good demonstration of the different sky conditions I had to work with.

Oh, and, I finally downloaded the new PHD2 release with the multi-star guiding. What a difference! It cut my RMS in half in both axes.