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- 1-18 Thursda  7: 5  17: 3   36.1  -20.50   -10.4  14.03  -24.7
        19 Friday   7: 4  17: 5   36.0  -20.29   -10.7  13.99  -24.3
        20 Saturda  7: 3  17: 6   35.8  -20.08   -11.0  13.96  -24.0

Average for   3 days
from   3 values is  7: 4  17: 5   36.0  -20.29   -10.7  13.99  -24.3

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  d18.01.2018 t10:32 l16.6 f49.2 ut1  h-6 n2 i1