Scanamorphos: a map-making software for Herschel and similar scanning bolometer arrays

摘要

Scanamorphos is one of the public softwares available to post-process scanobservations performed with the Herschel photometer arrays. Thispost-processing mainly consists in subtracting the total low-frequency noise(both its thermal and non-thermal components), masking high-frequency artefactssuch as cosmic ray hits, and projecting the data onto a map. Although it wasdeveloped for Herschel, it is also applicable with minimal adjustment to scanobservations made with some other imaging arrays subjected to low-frequencynoise, provided they entail sufficient redundancy; it was successfully appliedto P-Artemis, an instrument operating on the APEX telescope. Contrary tomatrix-inversion softwares and high-pass filters, Scanamorphos does not assumeany particular noise model, and does not apply any Fourier-space filtering tothe data, but is an empirical tool using purely the redundancy built in theobservations -- taking advantage of the fact that each portion of the sky issampled at multiple times by multiple bolometers. It is an interactive softwarein the sense that the user is allowed to optionally visualize and controlresults at each intermediate step, but the processing is fully automated. Thispaper describes the principles and algorithm of Scanamorphos and presentsseveral examples of application.