360 panoramas of light pollution domes shot with

360° panoramas of light pollution domes shot with a digital camera Pierre Brunet Association Nationale pour la Protection du Ciel Nocturne www. astrosurf. com/anpcn 01 60 82 75 55

Content n n n n n Aims Means A typical result Sensibility to the location : correlation to the Cinzano/Falchi/Elvidge/Baugh Atlas of the artificial night sky brightness Sensibility to the location : moving a few kilometers away Sensibility to the night hour : 3 hours apart Sensibility to the time of the year Sensibility to the meteorological conditions Conclusion and perspectives 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Aims n n n n To show the light pollution intensity compares to the stars light To show the extent of light pollution domes To show light pollution domes compare between themselves (cities vs cities) To show light pollution compare between regions To give quantitative values ( digital camera) (to come) To give an evolution with time (to come) The need for a fast and simple procedure : shooting the whole celestial vault in a single operation 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Means n Then ¡ ¡ A Single Lens Reflex with a f/1. 8 -50 mm lens, A stainless steel hemi-spherical bowl ( 360° field of view), More on this technic → n And now ¡ A digital camera (Nikon Coolpix 5400) with a f/2. 85. 6 mm fish-eye lens (Nikon FC-E 9) (190° field of view). 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Means : the present procedure n ¡ ¡ ¡ n N 1 Digital camera (1): ¡ 2 5 megapixels 100 ASA f/2. 8 3 minutes exposure Noise reduction (dark frame) Full resolution in TIF format 15 Mo. White balance : daylight E O S 4 3 Adobe Photoshop Elements LE 2. 0 processing : ¡ ¡ Rotating (2) : North to the top Croping (3) Filtering (4) : polar coordinates → cartesian coordinates Scaling to 95° 360° (5) N E S O N 5 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

A typical result : Livernon (Lot) N n n September 25 th, 2003, 01 h 26 AM, 5 km NW of Livernon on D 2 : Figeac-Livernon airport. Height 300 m. Clear. Level 4 on Bortle scale. Ciel & Espace/IGN E O S 169 km 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

n n September 25 th, 2003, 01 h 26 AM, 5 km NW of Livernon on D 2 : Figeac-Livernon airport. Height 300 m. Clear. Level 4 on Bortle scale. N N E Lacapelle Assier/Figeac/Livernon More on this database → Ciel & Espace/IGN A typical result : Livernon (Lot) 169 km S O Cahors Lunegarde Martel Brives 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Sensibility to the location : correlation to the Cinzano/Falchi/Elvidge Atlas of the artificial night sky brightness • Paris • Arpajon (91) • La Ferté-Alais (91) • Saint-Laurent-en-Grandvaux (39) • Craponne-sur-Arzon (43) • Cabrerets (46) • Livernon (46) • Chanac (48) Artificial/Natural night sky brightness : • < 10% : grey (< 0, 10 Mv) • < 33% : blue (< 0, 31 Mv) • < 100% : green (< 0, 75 Mv) • < 300% : yellow (< 1, 5 Mv) • < 900% : orange (< 2, 5 Mv) • < 2700% : red (< 3, 6 Mv) • > 2700% : white (> 3, 6 Mv) • Luc-en-Diois (04) • Veynes (05) • Rosans (05) • Sault (84) • Gordes (84) • Isle-sur-la-Sorgue (84) • Le-Pic-du-Midi-de-Bigorre (65) Cinzano, Falchi (Padova University), Elvidge, Baugh (NOAA) 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Le-Pic-de-Midi-de-B. (65) Sensibility to the location : correlation to the Cinzano/Falchi/Elvidge Rosans (05) - Verclause Atlas of the artificial night sky brightness Rosans (05) - Lemps n Veynes (05) The colored bars on the left side of the pictures gives the light pollution level according to the Cinzano & al. atlas of night sky brightness. Pictures are ordered according to the perceived light pollution level exhibited by these records. Craponne-sur-Arzon (43) Chanac (48) n Luc-en-Diois (04) Livernon (46) Rosans (05) - Col-de-Soubeyran Cabrerets (46) Sault (84) St-Laurent-en-Grandvaux (39) 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Le-Pic-de-Midi-de-B. (65) Rosans (05) - Verclause How to pollute an otherwise clear sky : the Rosans case ↓ Rosans (05) - Lemps Craponne-sur-Arzon (43) Veynes (05) Luc-en-Diois (04) Livernon (46) Rosans (05) - Col-de-Soubeyran Chanac (48) Cabrerets (46) Sault (84) St-Laurent-en-Grandvaux (39) 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Rosans (26) – Verclause Gordes (84) Craponne-sur-Arzon (43) La-Ferté-Alais (91) – Bouville Chanac (48) La-Ferté-Alais (91) – Villeneuve-s-A. Cabrerets (46) Isle-sur-la-Sorgue (84) Sault (84) Arpajon (91) St-Laurent-en-Grandvaux (39) Paris 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Sensibility to the location : Moving a few kilometers away Michelin Paris - Montparnasse Paris – Père Lachaise 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Sensibility to the night hour : 3 hours apart n There is nothing significant to expect, except for extinction of sporting facilities… 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

September Sensibility to the time of the year February n December January February March April n December The colored bars on the left side of the pictures gives the light pollution level according to the Cinzano & al. atlas of night sky brightness. The light pollution level perceived on the field remains about the same all year long for similar meteorological conditions (clear sky…). There is an asymptotic light pollution level that can not be gone through. April May 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Sensibility to the meteorological conditions n n Haze strongly reinforces near light pollution domes, and dims far ones. But it remains an asymptotic light pollution level that can not be gone through. Cabrerets (46) Livernon (46) Rosans (05) Chanac (48) 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

Conclusion and perspectives n n n Agreement between the Cinzano & al. night sky brightness atlas and the field situation (height must be accounted for) ; fair homogeneity of the field situation within each proposed pollution level (white, red, …, grey). In a given location, there is not much to expect from the time of the year, and quite nothing from the hour in the night. Meteorological conditions are a key feature, but sky transparency exhibit an asymptotic value according to the pollution levels defined by Cinzano & al. Digital data may lead to quantitative values for the night sky brightness (to come). Keeping a same data acquisition procedure give access to the evolution with time of light pollution (to come). 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004

How to pollute an otherwise clear sky The Rosans (05) case : n A small village brightly lit all through the night… 4 th Dark-Sky European Symposium, Paris, September 24 -25, 2004