The meteorological conditions of Campo Imperatore

The quality of an astronomical site mainly depends on its meteorological characteristics.

Geographical latitude and elevation, that are also important, could not change so much the situation of a rainy or mainly clouded site. Because of all these, the maximum attention is paid during the selection of sites to be used for astronomical observatories in the meteorological condition testing.

Using the meteo station and the readings of the seeing sensor that simultaneously reports the turbulence of the atmosphere and the presence of clouds, it is calculated the percentage of time useful for astronomical observations. This percentage takes into account also temperature, wind speed and humidity to select only the time fraction really available to observations.

Observational time fraction


Outside Temperature
Wind Speed
Wind Gust
Wind Direction
Relative Humidity

The prevailing winds at Campo Imperatore are aligned along the East-West direction with an obvious dependance of the intensity on the day hours that makes night time calmer on average with great advantage for observational activity.


The Observatory meteorological archive contains relative pressure, wind, temperature and humidity since 2010.  

As well as observing stars from towns is made practically impossible because of light pollution, also the astronomical observatories suffer very much sky brightness. For this reason the high mountain dark skies are usually the better choice for an observatory and the quality of an astronomical site is also measured through its sky brightness. The values shown in the following table have been measured in 2016 at Campo Imperatore pointing to the zenith, with no Moon and are in magnitudes so that higher values correspond to a darker sky.

band Sloan u' 22.7 mag/arcsec²
band Sloan g' 21.9 mag/arcsec²
band Sloan r' 20.7 mag/arcsec²
band Sloan i' 20.4 mag/arcsec²
band Sloan z' 19.3 mag/arcsec²
band Johnson J 15.2 mag/arcsec²
band Johnson H 13.4 mag/arcsec²
band Johnson K 12.6 mag/arcsec²

The Seeing term represents the point-like source (stars) image blurring due to atmospheric turbulence. Since the larger is the the seeing value and the more a source image is spread on a wider area on the sensor, it is clear that the suitability of the instrument to detect faint objects is reduced as well.
At Near Infrared wavelenghts the seeing value is approximately halved with respect to visual band measurements giving huge observational advantages.