How Clear was your Sky? -- Your Observations

The project on light pollution was one of the Collaborative Projects for Astronomy On-Line. A preliminary report has been given by ESO astronomers Richard West and Christian Drouet-d'Aubigny - thank you very much! In the meantime I got the time to take a closer look to the data:

Unfortunately the weather during the Astronomy On-Line project was extremely bad in Europe. Till now it was not possible to see Ursa Minor here in Osnabräck!!! And then the moon was waxing and brightening the evening sky so that the limiting magnitude got worse. Nevertheless 25 people sent their reports - many thanks to them all - all are cited below!

Some small results:

• At one city the limiting magnitude can vary much, e.g. in Sofia, Bulgaria, or Giarre, Italy. Reasons might be:
  • Observers with differing observing experience: a more experienced observer might see fainter stars, while a beginner might even misidentify the stars. However it is fascinating to have a limiting magnitude of 5.0 or even 6.3 at a capital!
  • Observers might have been not enough dark adapted, e.g. for about 15 minutes.
  • The observers might have been at different places of the city: those seeing fainter stars observed at a darker place, while the observer with the bright limiting magnitude was at a well illuminated place. This result experienced the group at Malaga, Spain.
• The moon was already very disturbing as remarked by many participents - often more than artificial lights!
• Unfortunately we can not derive a map of light pollution in Europe as there are too few data. The results projected onto an ESO Meteosat weather image of November 18th (I found none for the hot days) can be seen here: in red are shown places where the faintest stars were 3.5 mag, yellow with limiting magnitude 3.5 - 4.5 mag, and blue with limiting magnitude fainter than 4.5 mag.

Some proposals for own projects:

If you have contact to national astronomy associations, try to organize a nationwide project to determine light pollution in measuring the limiting magnitude. Examples are the StarWatch projects in Japan, US, Canada and the Sky Glow Project in UK. Especially for the last example you find a very nice chart of light pollution in the UK - but many people participated!

In measuring the limiting magnitude you can get a feeling for light pollution. Then you can point other people to the problem. By this way you learn to use lamps more efficient and save energy and ... the starry sky!

Location	Country	Latitude	Longitude	Observer	Magnitude
Sliven	Bulgaria	42.7 N	26.5 E	Ivelina Momcheva	5.0
Sofia	Bulgaria	42.68 N	23.5 E	Baltova Kremena	6.3
Sofia	Bulgaria	42.68 N	23.5 E	Hristo Hristov	5.0
Sofia	Bulgaria	42.41 N	23.5 E	Vladimir Georgiev	3.0
Conception	Chile	36.8 S	72 W	Juan Seguel	5.6
Munich	Germany	48.1 N	11.6 E	Rudolf Brendler	3.7
Bologna	Italy	44.50 N	11.33 E	Giada Leoni	4.4
Bologna	Italy	44.5 N	11.3 E	Maurizio Casadio	4.4
Bologna	Italy	44.5 N	11.3 E	Anna Serra	4.4
Bologna	Italy	44.5 N	11.3 E	Cristina Arato	4.4
Giarre	Italy	37.44 N	15.13 E	Petralia Placido	2.1
Giarre	Italy	37.44 N	15.13 E	Emmanuelle Mangano	5.0
Giarre	Italy	37.44 N	15.13 E	Michele Belfiore	4.9
Giarre	Italy	37.44 N	15.13 E	Carmelo Adornetto	2.1
Trieste	Italy	45.5 N	13.5 E	Conrad Boehm	4.2
Rocca Priora	Italy	41.47 N	12.5 E	Marcello Torsoli	5.6
Varedo	Italy	45.6N	9.2E	Luca Mauri	4.2
Marousi	Greece	37.58 N	23.43 E	Manolis Zoulias	3.0
Thebes	Greece	38.20 N	23.20 E	Hatzihronis Epaminondas	4.9
Volos	Greece	39.33 N	23.8 E	Kostas Mavrommatis	4.4
Volos	Greece	39.33 N	23.8 E	Loukas Zachilas	2.1
Malaga	Spain	36.7 N	4.7 W	Belin Martmn-Alarccsn	4.9
Malaga	Spain	36.7 N	4.7 W	Josi Dommnguez-Montoya	3.0
Wichita Falls (TX)	U.S.A.	33.51 N	98.29 W	Teresa May	4.2
Macclesfield	U.K.	53.26 N	2.1 W	Anne Cohen	4.4

Send comments to Andreas Haenel (Email: ahaenel@rz.uni-osnabrueck.de and
URL: http://www.physik.Uni-Osnabrueck.DE/students/ahaenel).