This is a tough one, but one of my better results! This galaxy is hardly brighter than the background and other stars around it, but a large amount of data, coupled with a new background extraction technique, helps substantially. The nickname the "hidden" galaxy is spot on.
Concerning this background extraction method, it came from an article from the Pixinsight team located
here .
This method is incredibly revolutionary in extracting challenging or strong gradients from images that suffer from light pollution or minimal background presence (i.e., when the entire image contains signal). It relies on taking data at an additional focal length (smaller), such as with a telephoto lens or small telescope, and then performing standard background extraction on this model image (which is usually straightforward, because the image should contain abundant background points, which allows DBE to be used in Pixinsight). The model image is then cropped and aligned to the target image, which produces a poor-resolution, but low-gradient version of the target image (because background gradients shouldn't vary widely over the small region of interest in the model image). After using wavelet-based blurring of both the target and model images, and subtracting the latter from the former, only a blurred version of the unwanted gradients remains. This gradient image is subtracted from the original target image to complete the background extraction.
I will likely outline the steps taken on this image on my
website at some point in the near future.
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