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First results from the Loss of the Night app

First results from the Loss of the Night app. Christopher Kyba, Annette Krop-Benesch , Franz Hölker Freie Universität Berlin / IGB 13 th European Symposium 2013 Pamplona, Spain September 14, 2013. Background: GLOBE at Night. NELM. Kyba et al . Sci Rep ( 2013). Problems with GaN.

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First results from the Loss of the Night app

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  1. First results from the Loss of the Night app Christopher Kyba, Annette Krop-Benesch, Franz Hölker Freie Universität Berlin / IGB 13th European Symposium 2013 Pamplona, Spain September 14, 2013

  2. Background: GLOBE at Night

  3. NELM Kyba et al. Sci Rep (2013)

  4. Problems with GaN • Can’t identify constellations in the city • Δm is fairly large for individual observations (~1.2 mag) • Atmospheric correction?

  5. Solution: Verlust der Nacht app! • Part of BMBF Wissen-schaftsJahr 2012 • Programmed by Cosalux • Based upon Google Sky program • Lots of information about artificial light at night inside app

  6. Star selection • From 10o to 45o from zenith • Mag<5.2 • Only ~1000 stars already in Google app

  7. Star selection: Stage 1 Start: Identify brightest star in sky (mnew) Identify new star in range m+0.5<mnew<m+1 Assign user new star with mnew Is star found? Yes No Proceed to Stage 2

  8. Star selection: Stage 2 Assign user star with mnew New star: 10% brighter 70% slightly fainter 20% much fainter Is star found? Yes Unsure New star: 50% much brighter 40% slightly brighter 10% slightly fainter No Identify much brighter star m-1.5<mnew<m-0.5

  9. Example Data 5 Stellar magnitude 4 3 2 1 0 Time (minutes)

  10. Dresden observations 5 not visible Stellar magnitude 4 3 2 1 0 Time (minutes)

  11. Dresden observations 5 not visible not sure Stellar magnitude 4 3 2 Cinzano ~4.66 Fit ~4.0 (0.9) 1 0 Time (minutes)

  12. Global app usage

  13. Data submission over time 1000 200 June April August

  14. Data submission over time 100 Good observation % 50 0 June April August

  15. Problem: Not enough urban data • Faintest stars in app have mag ~5 • App is only designed for urban astronomy!

  16. Problem: Not enough urban data NELM<4.8 NELM<4 Cinzano pop>9bn • Germany: 25% • Greece: 47% • Japan: 63% • Spain: 57% • USA: 62% • EU: 38% Cinzano pop>27bn • Germany: 0% • Greece: 17% • Japan: 27% • Spain: 25% • USA: 30% • EU: 8% App users: 2% GaN: 6% App users: 21% GaN: 32%

  17. Which stars are best? Big Dipper Draco Megrez(HR 4660) • mag 3.31 • 20 seconds • Found 91% • Unsure 3% • Easier star Edasich(HR 5744) • mag 3.29 • 31 seconds • Found 66% • Unsure 18% • Harder star

  18. Going forward • Need more urban users! • Expansion to 10 languages • Loss of the Night blog: www.lossofthenight.blogspot.com • Search for additional funding

  19. Acknowledgements The app and our project is funded through: Verlust der Nacht German Ministry of Education and Research BMBF-033L038A Thanks to Google for making Sky Map source code available, to GLOBE at Night for consulting in the app development, and to app testers! Title illustration: Light pollution It’s not pretty: Jeremy Stanley (Wikimedia Commons)

  20. Urban park in Berlin 5 not visible not sure 4 Stellar magnitude 3 2 1 Time (minutes)

  21. Maximum likelihood fit 1 Probability 0 1 3 5 NELM

  22. Maximum likelihood fit 1 Probability 0 1 3 5 NELM

  23. Citizen Science Works! 100x Sternenhimmel Sky brightness Sternenhimmel Observed sky brightness

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