Astrological calculations normally return results as "Universal Time," for practical purposes, universal time (UT) is the same as Time-Zone_0 (TZ0), Greenwich Mean Time (GMT) or winter time in London. Most countries operate on different time zones for part or all of the year and may/may-not adjust their clocks during the year.
 
Fortunately .Net has "Built-in" extensions for the Date variable type and these extensions perform the necessary local time conversions without complex code.
To convert universal time to Local Time, you can use .ToLocalTime()
Dim LocalTime1 As Date = UtTime.ToLocalTime() When calculating the events of Equinoxes and Moon Phases, it is important to use .ToLocalTime. Time-zone changes can push the event before of after midnight and change the event date. Astrlogical calculations often rely on a huge list of harmonic adjustments. Practical limitiations can restrict the number of adjustments a program can process, hence, a small error (often less than 20 minutes) is normal.

DigitalDan.co.uk