NavList:

For those of you who are also interested in the subject and would like to help enhancing my data set: You are welcome to provide your own timings of the last sun ray at the sea horizon. In this case please send me the following information:

Time (UT) measured to +/-1s with a calibrated watch. (The watch should be accurate to +/-1s. Depending on the conditions the timing itself of the last sun ray may actually be considerably less precise.)
Coordinates of observer (GPS or map) within e.g. about +/- 50m
Height of eyes estimated within about +/- 20%
(please mention if one of these values is expected to be less accurate than indicated)

Environmental data of observation (they may eventually be from a nearby weather station with comparable conditions, in this case mention also the weather station where the data have been taken from):
Atm. pressure and
air temperature
My intention is trying to improve the estimates (reducing the difference between observation and calculation) by using also the following additional information:
rel. humidity in %,
clouds (if possible covered amount estimated in %),
wind speed and also the
sea (surface) temperature (if known).

Thank you.

Marcel