For migration project I needed a function to convert a UNIX timestamp to Notes Date /Time. Here is the function I used

Function Timestamp2Date(timestamp As Double) As String

Dim dt As New NotesDateTime("01/01/1970 00:00:00")
Dim dd As Integer, hh As Integer, ss As Double

dd = Fix(timestamp / 86400)
ss = (timestamp Mod 86400) Mod 3600
hh = Fix(ss / 3600)
hh = hh + 1

Call dt.AdjustDay(dd)
Call dt.AdjustHour(hh)
Call dt.AdjustSecond(ss)

Timestamp2Date = Format(dt.LSLocalTime, "dd/mm/yyyy hh:mm:ss")
End Function

Sub Click(Source As Button)
Msgbox Timestamp2Date(1115986380)
End Sub

will convert the UNIX timestamp 1115986380 to “13.05.2005 02:13:00”