RandomCoder, Cableguy,
Thank you both for your quick assistance.
Sorry, I should have been more precise. My JulianDate calculation routine accepts date and time in units of Ticks, such as JulianDate(Now).
However, when date and time, as selected with a Calendar control for date and NumericUpDown Controls for time, are other than Now then these selections need to be converted to Ticks.
I have come to the following solution:
JulianDate(DateParse(Date(cal1.Value)) + 1/24 * (numGMHour.Value + numGMMin.Value / 60 + numGMSec.Value / 3600) * cTicksPerDay)
The JulianDate routine accounts for time zone and DST.
I've spent 2 hours experimenting last night without success but just a few minutes to the solution after reading your responses this morning.
Actually, it's my first time to employ the Calendar control, too
Thanks a lot guys!
Robert