According to the official website [1] (which is linked to from TFA), the images were processed using PixInsight, a program popular among amateur astronomers. T

According to the official website [1] (which is linked to from TFA), the images were processed using PixInsight, a program popular among amateur astronomers. This page: [2] explains how PixInsight performs image alignment; it turns out to be a pretty complex (and interesting) process. The same page also explains the process of merging images. [1] http://www.cielaustral.com/galerie/photo95.htm?fbclid=IwAR3GMt0zg_9VrcXH3moy7-lR7stH2Gb-ZOYPpvpTKMZooK7LpMBa97PQx2Y http://www.cielaustral.com/galerie/photo95.htm?fbclid=IwAR3G... [2] http://pixinsight.com/doc/tools/StarAlignment/StarAlignment.html http://pixinsight.com/doc/tools/StarAlignment/StarAlignment....