Calibrating and Stacking images over multiple sessions

The key to better AP images is integration time. Most of the software accounts for stacking images for multiple sessions, but it’s not always intuitive.

DeepSkyStacker has the group tabs at the bottom (super easy)

AstroPixelProcessor has imaging sessions directly in the image load workflow, including custom filter names which is really awesome.

PixInsight is the problem child. That said, the keywords are the trick.

Especially for PixInsight this should be common knowledge by now, and it’s also how I segmented my mosaic for Sh2-240. All you have to do is use the keywords.

PixInsight parses both the filename and the FITS headers which can be used for keyword designations, using the syntax <‘KEYWORD_VALUE’> So if you wanted to break your imaging into sessions (or nights) your filename could look like this.

Light_30_Bin1_294_gain120_SESSION_1_20220305_195634_-20c_0001.fit

Pixinsight will parse that out and you can use the “SESSION” identifier with the 1 as the value to increment your nights of shooting. You could use “PANE” for mosaics (however many) or even “BANANA” if you wanted to. PI doesn’t care.

Using the GROUPING KEYWORDS section on the right side of WBPP you can set the segmentation for the images. Preprocessing is generally where you would want to segment your calibration, and post processing is where you can segment image registration.

For example in my mosaic, I pre-processed all of the images by session (matching my calibration frames to the lights from more than one pane and by filter) and aligned and registered them based on which pane of the mosaic they were in during post-processing. It’s very easy once you sit down and think about it.

If you’re still struggling, Adam Block’s videos go in-depth in how to use WBPP in its various iterations, check out his YouTube videos and processing subscription based training.

My video below for visual learners :)