NachtMeetnet is a tradename under Sotto le Stelle (Registered Utrecht KvK 30167055)

Special phenomena

On this page the graphs are presented of the night sky brightness during the night of September 27 to 28, 2015 with a lunar eclips. The graph at right is shown with comments and explanation. The horizontal axis show the time in GMT. Which is two hours earlier than the Dutch summer time. The lunar eclips started at  0:11 GMT. At 3:07 the moon entered the shadow of the Earth (umbra). The altitude of the moon was 34 degrees at that moment. The total eclipse lasted from 2:11 till 3:24. At 4:27 the eclips ended at which the alitude of moon was 11 degrees above the horizon. The graph shows two units of sky brightness at the left and right axis. The line in the graph starts from above during dusk. During the night the line is low and during dawn the line rises again during sun rise.

At Arkemheen and Kootwijk some clouds were present at about 24:00 GMT, as can be seen by the upward peaks.  During the eclipse there was almost a clear sky everywhere as can be seen by the smooth line, especially at Woensdrecht. At all locations the samen pattern can be seen. After dusk the night sky brightness increases due to the rising moon. At about 24:00 GMT the maximum night sky brightness has been reached. Then the night sky brightness decreases  during the next 2 hours. At first slowly, then rapidly and then slowly again. This is a typical behviour during the eclipse. At the maximum of the eclipse the moon is also very low at the sky and has hardly any influence on the night sky brightness. Shortlly after dawn starts due to the rising sun.

What stands out is that the decrease in night sky brightness is different for the different locations. At Kootwijk and Oostkapelle this is large, while at Utrecht and Tata Steel this is far more less. This is due to the fact that Kootwijk and Oostkapelle are dark locations, while  at Utrecht and at Tata Steel the night sky is brighter due to illumination.
Lunar eclipse during September 27/28, 2015
Darkness in the Netherlands online