Carving out the low surface brightness universe with NoiseChisel
  NoiseChisel is a program to detect very low signal-to-noise ratio (S/N)
features with minimal assumptions on their morphology. It was introduced in
2015 and released within a collection of data analysis programs and libraries
known as GNU Astronomy Utilities (Gnuastro). The 10th stable version of
Gnuastro was released in August 2019 and NoiseChisel has significantly
improved: detecting even fainter signal, enabling better user control over its
inner workings, and many bug fixes. The most important change until version
0.10 is that NoiseChisel's segmentation features have been moved into a new
program called Segment. Another major change is the final growth strategy of
its true detections, for example NoiseChisel is able to detect the outer wings
of M51 down to S/N of 0.25, or 25.97 mag/arcsec2 on a single-exposure SDSS
image (r-band). Segment is also able to detect the localized HII regions as
"clumps" much more successfully. For a detailed list of improvements after
version 0.10, see the most recent manual. Finally, to orchestrate a controlled
analysis, the concept of reproducibility is discussed: this paper itself is
exactly reproducible (commit 751467d).
