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Seminário de Astronomia: Carving out the low surface brightness universe – Mohammad Akhlaghi (Instituto de Astrofísica de Canarias)
9 de outubro de 2019:12:30 - 13:30
Astronomical instrumentation has greatly advanced over the last 40 years: with digital detectors, space telescopes and +8m class ground-based telescopes for example. However, in the methods/software regime, the signal-based detection paradigm from the 1970s (for example from Petrosian or Kron, mostly used as implemented in SExtractor from the mid-1990s) is still the dominant method of extracting high-level catalogs from the low-level image pixels. In this talk, after reviewing the major systematic biases regarding astronomical object detection that is inherent to the old methods, I will introduce a fundamentally different noise-based paradigm for detecting signal with any shape and low signal-to-noise. With thresholds that are far below the Sky value, and non-parametric expansion into noise, it is successfully able to detect very diffuse and irregularly shaped signal in noise (galaxies). The software implementation is called NoiseChisel (part of GNU Astronomy Utilities (or Gnuastro). It is a large package of useful programs and libraries for astronomical data analysis directly on the command-line without the need to use mini environments like IRAF or Python. It fully conforms with the GNU Coding Standards for easy integration into all Unix-like operating systems (GNU/Linux and MacOS for example) with familiar installation, usage and documentation. I will conclude with a discussion on reproducible scientific papers and a solution that has already been implemented to have exactly reproducible scientific papers.