Outside the Netherlands measurements of the night sky brightness also take place, such as in Germany, Great Britain, Spain, Austra and Italy. This takes place occasionally with advanced camera's or continuously similar as at NachtMeetnet. Also worldwide several groups are active in the monitoring of the night sky brightness (such as in Hong Kong, the US and Canada).
At this moment there is not yet an international standardized measruing method to measure the night sky brightness. There are also different types of measuring equipment to measure the night sky brightness, such as manual and full automated and several types of continuous measuring light sensors.
In order to get a good comparison between the different measuring equipment and measuring methods there is a knowledge exchange program within the EU (named COST) for scientific institutes and companies. Within this knowledge exchange program exists a project called LoNNe for instiutes and companies to exchange knowledge in the fielsd of night sky brightness. LoNNe stands for Loss of the Night Network (for more information see: http://www.cost-lonne.eu/)
In 2015 NachtMeetnet has performed comparison measurements with a number of its measuring instruments with near Florence in Italy. The report can be found at the LoNNe website: http://www.cost-lonne.eu/wp-content/uploads/2015/04/2015_LoNNe_IC_Report.pdf. Through this international cooperation the knowledge is increased how and which method is the best for monitoring the night sky brightness.
In May 2016 the last international comparison has taken place in Northern Spain at an astronomical observatory in an astronomical park at MontSec (http://www.parcastronomic.cat/#!visita-nocturna/crx2). NachtMeetnet has also participated in this intercomparison. The resulst of this intercomparison are shown here: www.cost-lonne.eu/wp-content/.../2016_IC_Report_withDOI.pdf
Darkness in the Netherlands online
NachtMeetnet is a tradename under Sotto le Stelle (Registered Utrecht Nr. 30167055)