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Träfflista för sökning "WFRF:(Popescu Marcel) srt2:(2020-2023)"

Sökning: WFRF:(Popescu Marcel) > (2020-2023)

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1.
  • Farnocchia, Davide, et al. (författare)
  • International Asteroid Warning Network Timing Campaign: 2019 XS
  • 2022
  • Ingår i: The Planetary Science Journal. - : Institute of Physics Publishing (IOPP). - 2632-3338. ; 3:7
  • Tidskriftsartikel (refereegranskat)abstract
    • As part of the International Asteroid Warning Network's observational exercises, we conducted a campaign to observe near-Earth asteroid 2019 XS around its close approach to Earth on 2021 November 9. The goal of the campaign was to characterize errors in the observation times reported to the Minor Planet Center, which become an increasingly important consideration as astrometric accuracy improves and more fast-moving asteroids are observed. As part of the exercise, a total of 957 astrometric observations of 2019 XS during the encounter were reported and subsequently were analyzed to obtain the corresponding residuals. While the timing errors are typically smaller than 1 s, the reported times appear to be negatively biased, i.e., they are generally earlier than they should be. We also compared the observer-provided position uncertainty with the cross-track residuals, which are independent of timing errors. A large fraction of the estimated uncertainties appear to be optimistic, especially when <0 2. We compiled individual reports for each observer to help identify and remove the root cause of any possible timing error and improve the uncertainty quantification process. We suggest possible sources of timing errors and describe a simple procedure to derive reliable, conservative position uncertainties.
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2.
  • Kruk, Sandor, et al. (författare)
  • The impact of satellite trails on Hubble Space Telescope observations
  • 2023
  • Ingår i: Nature Astronomy. - : Springer Nature. - 2397-3366. ; 7, s. 262-268
  • Tidskriftsartikel (refereegranskat)abstract
    • The recent launch of low Earth orbit satellite constellations is creating a growing threat for astronomical observations with ground-based telescopes1–10 that has alarmed the astronomical community 11–16. Observations affected by artificial satellites can become unusable for scientific research, wasting a growing fraction of the research budget on costly infrastructures and mitigation efforts. Here we report the first measurements, to our knowledge, of artificial satellite contamination on observations from a low Earth orbit made with the Hubble Space Telescope. With the help of volunteers on a citizen science project (www.asteroidhunter.org) and a deep learning algorithm, we scanned the archive of Hubble Space Telescope images taken between 2002 and 2021. We find that a fraction of 2.7% of the individual exposures with a typical exposure time of 11 minutes are crossed by satellites and that the fraction of satellite trails in the images increases with time. This fraction depends on the size of the field of view, exposure time, filter used and pointing. With the growing number of artificial satellites currently planned, the fraction of Hubble Space Telescope images crossed by satellites will increase in the next decade and will need further close study and monitoring.
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