Length of the Night

as an interval between the PM and AM moments of Sun passing a given angular height (default -6, for the ``civil night''):

Year:   Month:   Day:
Longitude: (western as -)   Latitude:
Your Time - UTC:  h
The relevant angular height of Sun is degrees
next days will be computed as well,
with a step of day(s).
   save settings    use my saved settings

Another option is to use your own command line (ev. overriding all previous data):

(`?' gives help).

The centre of Sun is at a place with coordinates [Lambda=16.6, Phi=49.2]
 in an angular height of h =-6.0
 in the following morning and evening moments (given in UTC+ 1h):

 year-month-day  morning evening twilight decl.  >mean  night   A-W
                       h:min     / 1 min   /1   /1min   /1h    /1
2018- 3-22 Thursda  5:20  18:41   32.0    0.71    -6.9  10.66    8.1
        23 Friday   5:18  18:42   32.0    1.10    -6.6  10.60    8.7
        24 Saturda  5:16  18:44   32.0    1.49    -6.3  10.54    9.3

Average for   3 days
from   3 values is  5:18  18:42   32.0    1.10    -6.6  10.60    8.7

Meaning of remaining columns:
 Twilight    is an interval to/from h=-0.8
 Declination of Sun is given for the moment of local mean noon,
 >Mean       says how much is the Sun ahead of the mean time,
 Night       is the time the Sun travels below h,
 A-W         is departure of solar azimuth from the west when at h afternoon.

This is a result of the programme nights (available as a part of a package pas_jh.zip (1.2 MB) -- the needed Pascal units themselves are unzipped within this directory, the whole tree of my programmes within this directory) with a command line:
nights  d22.03.2018 t14:30 l16.6 f49.2 ut1  h-6 n2 i1