Darkness Clock

The Darkness Clock is visible in the Status panel of the Main Screen.
Related videos:
The Darkness Clock shows in real time what the “status” of the sky darkness is. It is focused on nights so it starts from the today's noon and ends in the tomorrow's noon in order to show all events during the full night.
Double click on the Darkness Clock opens the Deep Sky Darkness calculator.
Note: You have to set your imaging / observing site coordinates in Location Settings in order to get correct times and events.
Take a look on the free (yes, free - no ads or marketing) Androind and iOS versions of the Deep Sky Darkness Calculator - APT Darkness Clock
Darkness Clock

Noon to Sunset

This is the time between midday and sunset.

Nautical twilight

This zone combines the Civil and Nautical twilight.

Astronomical twilight

This is the Astronomical twilight.

Full darkness

If there is no Moon this is the time of the full darkness suitable for imaging deep sky objects.


A pointer that shows the current moment. It will start blinking 15 minutes before a zone change.

Sunrise to Noon

This is the time between sunrise and midday.


Shows when the Moon is above the horizon.