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Sökning: WFRF:(Guergouri Hichem)

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1.
  • Villarroel, Beatriz, et al. (författare)
  • A glint in the eye : Photographic plate archive searches for non-terrestrial artefacts
  • 2022
  • Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 194, s. 106-113
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we present a simple strategy to identify Non-Terrestrial artefacts [NTAs; Haqq-Misra and Kopparapu (2012)] in or near geosynchronous Earth orbits (GEOs). We show that even the small pieces of reflective debris in orbit around the Earth can be identified through searches for multiple transients in old photographic plate material exposed before the launch of first human satellite in 1957. In order to separate between possible false point-like sources on photographic plates from real reflections, we present calculations to quantify the associated probabilities of alignments. We show that in an image with nine "simultaneous transients" at least four or five point sources along a line within a 10 * 10 arcmin(2) image box are a strong indicator of NTAs, corresponding to significance levels of 2.5 to 3.9 sigma. This given methodology can then be applied to set an upper limit to the prevalence of NTAs with reflective surfaces in geosynchronous orbits.
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2.
  • Villarroel, Beatriz, et al. (författare)
  • Launching the VASCO Citizen Science Project
  • 2022
  • Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 8:11, s. 561-
  • Tidskriftsartikel (refereegranskat)abstract
    • The Vanishing & Appearing Sources during a Century of Observations (VASCO) project investigates astronomical surveys spanning a time interval of 70 years, searching for unusual and exotic transients. We present herein the VASCO Citizen Science Project, which can identify unusual candidates driven by three different approaches: hypothesis, exploratory, and machine learning, which is particularly useful for SETI searches. To address the big data challenge, VASCO combines three methods: the Virtual Observatory, user-aided machine learning, and visual inspection through citizen science. Here we demonstrate the citizen science project and its improved candidate selection process, and we give a progress report. We also present the VASCO citizen science network led by amateur astronomy associations mainly located in Algeria, Cameroon, and Nigeria. At the moment of writing, the citizen science project has carefully examined 15,593 candidate image pairs in the data (ca. 10% of the candidates), and has so far identified 798 objects classified as "vanished". The most interesting candidates will be followed up with optical and infrared imaging, together with the observations by the most potent radio telescopes.
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