Julian to regular date converter

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Option Explicit
Public Sub convert_from_julian()
 Dim row As Long
 Dim startrow As Long
 Dim theyear As String
 Dim themonth As String
 Dim theday As Integer
 Dim thetime As String
 Dim thedate As String
 Dim leapyear As Integer
 Dim julianday As Integer
 Dim Worksheetz As Integer
 Dim outcol As Integer
 Dim yearcol As Integer
 Dim daycol As Integer
 Dim timecol As Integer
 Dim rangeselect As String 
 
 ''''''''''''''''''''''''''
 '  variable initialization    '
 ''''''''''''''''''''''''''
 startrow = 1
 outcol = 1
 yearcol = 3
 daycol = 4
 timecol = 5
 Worksheetz = 1  
 ''''''''''''''''''''''''''
 
 row = startrow
 Do While Worksheets(Worksheetz).Cells(row, yearcol).Value <> ""
   theyear = Worksheets(Worksheetz).Cells(row, yearcol).Value
   julianday = Worksheets(Worksheetz).Cells(row, daycol).Value
   thetime = Worksheets(Worksheetz).Cells(row, timecol).Value    
   Select Case Len(thetime)
     Case Is = 1
       thetime = "00:0" & Right(thetime, 1)
     Case Is = 2
       thetime = "00:" & Right(thetime, 2)
     Case Is = 3
       thetime = Left(thetime, 1) & ":" & Right(thetime, 2)
     Case Is = 4
       thetime = Left(thetime, 2) & ":" & Right(thetime, 2)
   End Select
   
   If theyear Mod 4 = 0 Then
     leapyear = 1
   Else:
     leapyear = 0
   End If
   
   If julianday <= 31 Then
     theday = julianday
     themonth = "1"
   ElseIf julianday <= 59 + leapyear Then
     theday = julianday - 31
     themonth = "2"
   ElseIf julianday <= 90 + leapyear Then
     theday = julianday - 59 - leapyear
     themonth = "3"
   ElseIf julianday <= 120 + leapyear Then
     theday = julianday - 90 - leapyear
     themonth = "4"
   ElseIf julianday <= 151 + leapyear Then
     theday = julianday - 120 - leapyear
     themonth = "5"
   ElseIf julianday <= 181 + leapyear Then
     theday = julianday - 151 - leapyear
     themonth = "6"
   ElseIf julianday <= 212 + leapyear Then
     theday = julianday - 181 - leapyear
     themonth = "7"
   ElseIf julianday <= 243 + leapyear Then
     theday = julianday - 212 - leapyear
     themonth = "8"
   ElseIf julianday <= 273 + leapyear Then
     theday = julianday - 243 - leapyear
     themonth = "9"
   ElseIf julianday <= 304 + leapyear Then
     theday = julianday - 273 - leapyear
     themonth = "10"
   ElseIf julianday <= 334 + leapyear Then
     theday = julianday - 304 - leapyear
     themonth = "11"
   ElseIf julianday <= 365 + leapyear Then
     theday = julianday - 334 - leapyear
     themonth = "12"
   End If
   
   ' bring it all back together
   themonth = themonth & "/"
   theyear = "/" & theyear & " "
   thedate = themonth & CStr(theday) & theyear & thetime
   Worksheets(Worksheetz).Cells(row, outcol).Value = thedate
   rangeselect = Chr(64 + outcol) & CStr(row)
   ' ascii A = 65
   Range(rangeselect).Select
   Selection.NumberFormat = "m/d/yyyy hh:mm;@"
   row = row + 1
 Loop
 
 Range("A1").Select
 
 End Sub