Allsky Cam Cloud Detection

About this webpage

This webpage is meant to analyse the current level of cloudiness of the sky above the FACT telescope on La Palma by ckecking the night sky for stars and whether they are visible or not.

The following notation is used:

Issues or suggestions?

Leave a note at GitHub repo

Allsky cam images with star overlay, brightness and visibility annotation

CTA Skycam Magic Skycam

Stars are displayed as coloured dots. A green star is 100% visible, while a red star is covered up. the colour code gets calculated by image #3.
White triangles are sources. Names will be added soon.

Cloudmaps. Black=Cloud, White=Starry Sky

Cloudiness map of the sky. Black=cloud, white=no cloud. The outer regions of the image are always black because of cropping not because of clouds.
Rektangular artifacts are results of gaussian smoothing with NaN values, will be fixed soon.

Visibility of star vs star magnitude. Upper and lower limits

Kernel response (or 'visibility') vs star magnitude. Applying a LoG filter to the image, brighter stars have a higher filter response than smaller
and less intense ones. The green line marks the upper limit for good weather conditions. Stars above this limit are visible by 100%.
The red line marks the limit for bad conditions. Stars covered by clouds lie below this limit and are not visible at all. A linear scaling was aplied for stars in between.

Here you can see what it looks like if a cloud passes by