Filling flown hours day and night into a Log Book

[CZ_RAF]

Hi all,
I have never thought about this before but what was the rule to distinguish the number of hours flown by day and night?
From those Log Books I have seen I came to the conclusion there was no fixed or rounded numbers so it looks like that the actual sunrise and sunset times of the pacticular day may be thresholds?

TIA

Pavel

[bvs]

As far as I know - For logging night flying, 'night' is defined as the time between the end of evening civil twilight and the beginning of morning civil twilight.

So in Britain one could log 'night' flying by 1700hrs in mid winter but would have to wait until after 2200hrs during the summer.

Of course the times would have to be adjusted for Double Summer Time during WW2 :)