Sub logbooktypingchecker()
'Spreadsheet Typing Checker for Logbook Transcribers
'Programmer: James Ostiguy
'This version was completed: Aug. 16, 2012
'Last change: Sept. 11, 2012
'This routine evaluates up to 5000 plate entries for the following:
'1.  Compares (Start Time - R.A) with H.A. and reports the difference.
'2.  Determines that the R.A., Dec., H.A., Start, and Stop values are all within their respective ranges.
'3.  Checks for Start and Stop times being out of sequence.
'4.  Checks that the duration of the exposure is less than a maximum value.
'5.  Determines if the plate coordinates are below the horizon during the exposure.
'6.  When necessary, converts the time type to sidereal time by reading
'the time type entered in column N and writing the converted times to columns O and P.
'7.  Offers the option to display altitude angles for the Start and Stop times in columns Q and R.
'This routine only writes to columns L through R.
'All the information in these columns except the time type will be deleted after you have finished correcting
'any typing errors and noting any significant problems in the logbook data.

converttime = ""
If (Range("L1").Value <> "Error in R.A., H.A., or Start") Then 'Display information about this program
 extrafetures = "6.  When necessary, converts the time type to sidereal time by reading the time type" & Chr(13) & "entered in column N and writing the converted times to columns O and P." & Chr(13) & "7.  Offers the option to display altitude angles for the Start and Stop times in columns Q and R."
 extraline = "This routine only writes to columns L through R." & Chr(13) & Chr(13) & "Times recorded in most logbooks are in sidereal time.  Some logbooks used standard time or GMT." & Chr(13) & "Are time types other than sidereal time used in the logbook?"
 Message = MsgBox("Programmer: James Ostiguy" & Chr(13) & "This version was completed on Aug. 16, 2012" & Chr(13) & "Last change was made on Sept. 11, 2012" & Chr(13) & Chr(13) & "This routine evaluates up to 5000 plate entries for the following:" & Chr(13) & "1.  Compares (Start Time - R.A) with the Hour Angle and reports the difference." & Chr(13) & "2.  Determines that the R.A., Dec., H.A., Start, and Stop values are all within their respective ranges." & Chr(13) & "3.  Checks for Start and Stop times being out of sequence." & Chr(13) & "4.  Checks for unusually long exposures." & Chr(13) & "5.  Determines if the plate coordinates are below the horizon during the exposure." & Chr(13) & extrafetures & Chr(13) & Chr(13) & extraline, 3, "Spreadsheet Typing Checker for Logbook Transcribers")
 If (Message = 2) Then End
 If (Message = 6) Then converttime = "yes"
 
 'Determine Observation Location
 Location = InputBox("Enter the number corresponding to the" & Chr(13) & "observer location for the logbook." & Chr(13) & Chr(13) & " 1  Cambridge MA" & Chr(13) & " 2  Oak Ridge" & Chr(13) & " 3  Norwell MA" & Chr(13) & " 4  Taunton MA" & Chr(13) & " 5  Ossipee, NH" & Chr(13) & " 6  Arequipa" & Chr(13) & " 7  Bloemfontein" & Chr(13) & " 8  Mt. Harvard, Peru" & Chr(13) & " 9  San Jose, Peru" & Chr(13) & " 10  Willows, CA" & Chr(13) & " 11  Wilsons Peak, CA" & Chr(13) & "12 Jamaica" & Chr(13) & "13 McDonald Observatory" & Chr(13) & "14 Hanover, S. Africa" & Chr(13) & "15 Chuquicamata, Ch" & Chr(13) & "16 El Leoncito, Argentina" & Chr(13) & "17 CTIO" & Chr(13) & "18 Mt. John, NZ", "Location Selecter", 1)
 If (Message = 6 Or Message = 7) Then Range("M1").Value = "Other Messages for Loc. " & Location
 
 'Set Column Widths
 'Columns("K:K").ColumnWidth = 38
 Columns("L:M").ColumnWidth = 23
 
 If (converttime = "yes") Then
  Range("N1").Value = "Time Type pre"
  'Display information on time conversions and altitude angles.
  showalt = MsgBox("If this logbook has start times in standard time, daylight savings time, or GMT, then using capital letters" & Chr(13) & "type the abbreviation for the time zone in column N to see local sidereal times in columns O and P." & Chr(13) & Chr(13) & "Do you want altitude angles for the Start and Stop times displayed in columns P and Q?", 4 + 256, "Information for Time Type Conversion")
  'Set Column Widths
  Columns("N:N").ColumnWidth = 9.14
  Columns("O:P").ColumnWidth = 14
  'Store Values
  If (showalt = 6) Then Range("Q1").Value = "Alt. Ang. at Start": Range("R1").Value = "Alt. Ang. at Stop": Columns("Q:R").ColumnWidth = 14
  Range("O1").Value = "Converted Start"
  Range("P1").Value = "Converted Stop"
 End If
End If
 
'Establish the coordinates and time zone of the observation location.
Location = Trim(Right(Trim(Range("M1").Value), 2))
If (Location = 1) Then Lat = 42.38: lon = -71.1292: timezone = -5 'Cambridge MA
If (Location = 2) Then Lat = 42.5033: lon = -71.5583: timezone = -5 'Oak Ridge
If (Location = 3) Then Lat = 42.0538: lon = -70.7944: timezone = -5 'Norwell
If (Location = 4) Then Lat = 41.8997: lon = -71.0903: timezone = -5 'Taunton
If (Location = 5) Then Lat = 43.685341: lon = -71.116789: timezone = -5 'Ossipee, NH
If (Location = 6) Then Lat = -16.375: lon = -71.55: timezone = -5 'Arequipa
If (Location = 7) Then Lat = -29.0383: lon = 26.4042: timezone = 2 'Bloemfontein
If (Location = 8) Then Lat = -11.8756: lon = -76.7036: timezone = -5 'Mt. Harvard, Peru
If (Location = 9) Then Lat = -6.7297: lon = -79.84: timezone = -5 'San Jose, Peru
If (Location = 10) Then Lat = 39.525: lon = -122.1941: timezone = -8 'Willows, CA
If (Location = 11) Then Lat = 34.2153: lon = -118.0596: timezone = -8 'Wilsons Peak, CA
If (Location = 12) Then Lat = 18: lon = -77: timezone = -5 'Jamaica
If (Location = 13) Then Lat = 30.67164: lon = -104.02304: timezone = -7 'McDonald Observatory
If (Location = 14) Then Lat = -25: lon = 30: timezone = 2 'Hanover, S. Africa
If (Location = 15) Then Lat = -22.315: lon = -68.9292: timezone = -4 'Chuquicamata, Ch
If (Location = 16) Then Lat = -30: lon = -67: timezone = -3 'El Leoncito, Argentina
If (Location = 17) Then Lat = -30.1683: lon = -70.8042: timezone = -4 'CTIO
If (Location = 18) Then Lat = -43.9867: lon = 170.4666: timezone = 12  'Mt. John, NZ

'Label Headings
'Range("I1").Value = "Exposure"
'Range("I2").Value = "minutes"
Range("L1").Value = "Error in R.A., H.A., or Start"

'Set Variables to initial values
Dim mth(12) As Integer
MaxExpDur = 2.2 'max exposure time allowed without warning, in hours
Count = 5000 'maximum number of plates
If (Location = "") Then Lat = 42.4 'Approximate latitude of Cambridge, MA.
AltL = 10 'Lowest viewing angle above horizon allowed without a warning, in degrees."
pie = 3.1415926
prevtstop = 0
maxerror = 1
lastdate = Trim(Range("J2").Value)
precescor = Trim(Right(Trim(Range("N1").Value), 3))
startcount = 2
If (Trim(Range("A2").Value) <> 2) Then lastdate = Trim(Range("J3").Value): startcount = 3
For e = startcount To Count
'Create cell pointers
Be = "B" & e 'Plate number
De = "D" & e 'R.A.
Ee = "E" & e 'Dec.
Ge = "G" & e 'H.A.
Fe = "F" & e 'Start Time
He = "H" & e 'Stop Time
Ie = "I" & e 'Duration of Exposure
Je = "J" & e 'Date
Ke = "K" & e 'Comments
Le = "L" & e 'R.A., H.A., or Start Time Errors
Me1 = "M" & e 'Other Errors
Ne = "N" & e 'Time Type
Oe = "O" & e 'Converted Start Time
Pe = "P" & e 'Converted Stop Time
Qe = "Q" & e 'Altitude Angle at Start
Re = "R" & e 'Altitude Angle at Stop
Se = "S" & e

If (Range(Be).Value = "" And Range(Fe).Value = "") Then Range(Le).Value = "End": Range(Me1).Value = e - startcount & " rows checked": Exit For 'End if no plate number and no start time.

'Check for Start value.
If (Range(Fe).Value = "") Then
 note = "missing Start "
Else
 'Read Start Time
 Sts = 0
 Ststring = Trim(Range(Fe).Value) & " "
 Stlength = Len(Ststring)
 pos = InStr(Ststring, " ")
 If (pos = Stlength) Then
  noteM = noteM & "Check Start Time "
 Else
  sth = Trim(Left(Ststring, pos))
  Stmstring = Trim(Mid(Ststring, pos)) & " "
  Stmlength = Len(Stmstring)
  pos = InStr(Stmstring, " ")
  If (pos = Stmlength) Then
   stm = Trim(Stmstring)
  Else
   stm = Trim(Left(Stmstring, pos))
   Stsstring = Trim(Mid(Stmstring, pos))
   Sts = Val(Stsstring)
  End If
  stm = Val(stm) + Sts / 60
  tstart = Val(sth) + Val(stm) / 60
  If (tstart >= 24) Then noteM = "check start time " & noteM
  If (stm >= 60) Then noteM = "check start time " & noteM
 End If
End If
'Range(Re).Value = sth & " " & stm
'Check for Stop value.
If (Range(He).Value = "") Then
 note = note & "missing Stop"
Else
 'Read Stop Time
 Sps = 0
 Spstring = Trim(Range(He).Value) & " "
 Splength = Len(Spstring)
 pos = InStr(Spstring, " ")
 If (pos = Splength) Then
  noteM = noteM & "Check Stop Time "
 Else
  Sph = Trim(Left(Spstring, pos))
  Spmstring = Trim(Mid(Spstring, pos)) & " "
  Spmlength = Len(Spmstring)
  pos = InStr(Spmstring, " ")
  If (pos = Spmlength) Then
   Spm = Trim(Spmstring)
  Else
   Spm = Trim(Left(Spmstring, pos))
   Spsstring = Trim(Mid(Spmstring, pos))
   Sps = Val(Spsstring)
  End If
  Spm = Val(Spm) + Sps / 60
  tstop = Val(Sph) + Val(Spm) / 60
  If (tstop >= 24) Then noteM = "check stop time " & noteM
  If (Val(Spm) >= 60) Then noteM = "check stop time " & noteM
 End If
End If

'Read Date
daystring2 = "" 'clear second date
pagedate = Trim(Range(Je).Value)
If (pagedate = "") Then pagedate = lastdate: noteM = noteM & "Missing Page Date"
pos = InStr(pagedate, " ")
If (pos = 0) Then
 noteM = noteM & "Check Date "
 Datecondition = "unusable"
Else
 monthstring = Trim(Left(pagedate, pos))
 yearstring = Trim(Right(pagedate, 4))
 posd = InStr(pagedate, "-")
 If (posd = 0) Then
  datestring = Trim(Mid(pagedate, pos))
  pos = InStr(datestring, " ")
  posc = InStr(datestring, ",")
  If (pos = 0 And posc = 0) Then
   noteM = noteM & "Check Date "
   Datecondition = "unusable"
  Else
   If (posc = 0) Then
    daystring = Trim(Left(datestring, pos))
   Else
    daystring = Trim(Left(datestring, posc - 1))
    If (pos = 0) Then noteM = noteM & "Check Date "
   End If
   Datecondition = "usable"
  End If
 Else
  monthdaystring = Trim(Left(pagedate, posd - 1))
  pos = InStr(monthdaystring, " ")
  If (pos = 0) Then
   noteM = noteM & "Check Date "
   Datecondition = "unusable"
  Else
   daystring = Trim(Mid(monthdaystring, pos))
   Datecondition = "usable"
  End If
  dayyearstring = Trim(Mid(pagedate, posd + 1))
  pos = InStr(dayyearstring, " ")
  If (pos = 0) Then
   noteM = noteM & "Check Date "
   Datecondition = "unusable"
  Else
   daystring2 = Trim(Left(dayyearstring, pos))
   Datecondition = "usable"
  End If
 End If
End If

yr = Val(yearstring)
dy = Val(daystring)
dy2 = Val(daystring2)
platedate = monthstring & " " & dy & ", " & yr
mn = Val(Month(platedate))

'Compare Start and Stop Times
tstop = Val(Sph) + Val(Spm) / 60
tstart = Val(sth) + Val(stm) / 60
expduration = Trim(Range(Ie).Value)
'Range("S" & e).Value = expduration
If (expduration = "") Then
 'Check for Start and Stop times being out of sequence
 If (pagedate = lastdate) Then
  If (prevtstop > 12 And tstart < 12) Then setuptime = 24 + tstart - prevtstop Else setuptime = tstart - prevtstop
 Else:
  setuptime = 0
 End If
 If (tstart - tstop > 24 - MaxExpDur) Then exposuretime = 24 + tstop - tstart Else exposuretime = tstop - tstart
 If (setuptime < 0) Then noteM = "duration overlap " & noteM
 'Compare the Duration of Exposure with the maximum value.
 If (exposuretime > MaxExpDur) Then noteM = noteM & "extra long exposure "
Else
 difference = (Val(Sph) - Val(sth)) * 60 + Round(Spm - stm)
 If (tstart - tstop > 0) Then difference = difference + 24 * 60
 If (Abs(difference - Val(expduration)) > 1) Then noteM = noteM & "Check Exposure, Start, & Stop  "
End If

'Set value for next plate data test.
prevtstop = tstop

If (Datecondition = "usable") Then
 'Convert Time Type
 timecode = Trim(Range(Ne).Value)
 'timecode = InStr(timecode, "ST", 1)
 If (timecode = "") Then
  timetype = ""
 Else
  timetype = Left(timecode, 2)
  If (timetype = "UT" Or timecode = "GMT") Then
   timetype = "UT"
  Else
   timetype = Right(timecode, 2)
   If (timetype = "ST") Then
   Else
    If (timetype <> "DT") Then noteM = "Check Time Type  " & noteM
   End If
  End If
 End If
 If (timetype = "ST" Or timetype = "DT" Or timetype = "UT") Then
  maxerror = 7 'Increase maxerror for ST, DT, and UT time types.
  
  'Start Time
  yearinepoch = yr - 2000: CIGST = 18.69737: leepday = 0
  'If (yr < 1976) Then yearinepoch = yr - 1950: CIGST = (0.923459) * 24: If (yr > 1950) Then leepday = 1
  'If (yr < 1926) Then yearinepoch = yr - 1900: leepday = 0: CIGST = (0.81352-.175) * 24
  mth(1) = 0: mth(2) = 31: mth(3) = 59: mth(4) = 90: mth(5) = 120: mth(6) = 151: mth(7) = 181: mth(8) = 212: mth(9) = 243: mth(10) = 273: mth(11) = 304: mth(12) = 334
  If (yearinepoch / 4 = yearinepoch \ 4) Then
   If (yearinepoch > 0 And mn < 3) Then leepday = leepday - 1
   If (yearinepoch < 0 And mn > 2) Then leepday = leepday + 1
  End If
  'Correct for the change of date during the observing session.
  If (lastdate = pagedate) Then
   If (begintime > tstart) Then dy = dy + 1 ': Range(Qe).Value = Range(Qe).Value & " + 1 "
  Else
   begintime = tstart
  End If
  If (daystring2 = "") Then
  Else
   If (timetype = "ST" Or timetype = "DT") Then If (tstart < 12) Then dy = dy2 ': Range(Qe).Value = Range(Qe).Value & dy
  End If
  'Calculate days since epoch date
  days = yearinepoch * 365 + yearinepoch \ 4 + mth(mn) + dy - 1 + (Val(sth) + stm / 60) / 24 + leepday
  'Set time zone offset
  If (timetype = "ST") Then hoffset = timezone
  If (timetype = "DT") Then hoffset = timezone + 1
  If (timetype = "UT") Then hoffset = 0
  'Calculate the sidereal start time.
  siddays = (days - hoffset / 24 - 0.5) * 1.00273790935 + lon / 360 + CIGST / 24
  sidtime = (siddays - Int(siddays)) * 24
  sidh = Int(sidtime): sidm = Int((sidtime - sidh) * 60000) / 1000
  sth = sidh: stm = sidm
  obststart = tstart
  tstart = Val(sth) + Val(stm) / 60
  Range(Oe).Value = sidh & "h " & sidm & "m"
  stdays = days
    
  'Stop Time
  obststop = tstop
  'Calculate days since epoch date
  days = yearinepoch * 365 + yearinepoch \ 4 + mth(mn) + dy - 1 + (Val(Sph) + Spm / 60) / 24 + leepday
  'Correct for the change of date durring the observing session.
  If (obststart > tstop) Then days = days + 1 ': Range(Qe).Value = Range(Qe).Value & " + p1 "
  'Set time zone offset
  If (timetype = "ST") Then hoffset = timezone ': If (Val(Sph) < 12) Then days = days + 1
  If (timetype = "DT") Then hoffset = timezone + 1 ': If (Val(Sph) < 12) Then days = days + 1
  If (timetype = "UT") Then hoffset = 0
  'Calculate the sidereal stop time.
  siddays = (days - hoffset / 24 - 0.5) * 1.00273790935 + lon / 360 + CIGST / 24
  sidtime = (siddays - Int(siddays)) * 24
  sidh = Int(sidtime): sidm = Int((sidtime - sidh) * 60000) / 1000
  Range(Pe).Value = sidh & "h " & sidm & "m"
  Sph = sidh: Spm = sidm
  tstop = Val(Sph) + Val(Spm) / 60
 Else
  Range(Oe).Value = ""
  Range(Pe).Value = ""
 End If
Else
Range(Oe).Value = "Unusable Date"
End If

If (Range(Be).Value <> "" And Range(Be).Value <> " ") Then 'Skip to printing error messages if no plate number.

 'Read Dec.
 dec = Trim(Range(Ee).Value)
 VDec = Val(dec)
 If (Val(dec) > 90 Or Val(dec) < ILat - 90) Then noteM = "check Dec. " & noteM

 'Check for H.A. value.
 If (Range(Ge).Value = "") Then
  note = note & "missing H.A."
  HAh = 0
  HAm = 0
  eorw = "0"
 Else
  'Read H.A.
  HAs = 0
  HAstring = Trim(Range(Ge).Value)
  eorw = Right(HAstring, 1)
  pn = Left(HAstring, 1)
  If (pn = "-") Then pn = -1 Else pn = 1
  If (Val(eorw) >= 0 And Val(eorw) < 10) Then
   HAlength = Len(HAstring)
  Else
   HAlength = Len(HAstring) - 1
  End If
  HAstring = Trim(Left(HAstring, HAlength)) & " "
  pos = InStr(HAstring, " ")
  If (pos = HAlength) Then
   noteM = "Check H.A. " & noteM
  Else
   HAh = Trim(Left(HAstring, pos))
   HAmstring = Trim(Mid(HAstring, pos)) & " "
   HAmlength = Len(HAmstring)
   pos = InStr(HAmstring, " ")
   If (pos = HAmlength) Then
    HAm = Trim(HAmstring)
   Else
    HAm = Trim(Left(HAmstring, pos))
    HAsstring = Trim(Mid(HAmstring, pos))
    HAs = Val(HAsstring)
   End If
   HAh = Val(HAh)
   HAm = Val(HAm) + HAs / 60
  End If
 End If
 'Determine the sign of the H.A. value.
 EW = 0
 If (eorw = "w" Or eorw = "W") Then
  HAHr = HAh
  HAMn = HAm
  EW = -1
 End If
 If (eorw = "e" Or eorw = "E") Then
  HAHr = -HAh
  HAMn = -HAm
  EW = 1
 End If
 If (EW = 0) Then
  If (HAh <> 0 Or HAm <> 0) Then noteM = noteM & "check HA " 'Error if no direction is indicated
  HAHr = HAh
  HAMn = pn * HAm
 End If
 VHA = HAh + HAm / 60
 If (VHA > 12) Then noteM = "check HA " & noteM
 If (HAm >= 60) Then noteM = "check HA " & noteM
 'Range(Re).Value = HAHr & " " & HAMn
 
 'Check for R.A. value.
 If (Range(De).Value = "") Then
  If (dec < 90) Then note = note & "missing R.A."
  RAcondition = "unusable"
 Else
  'Read R.A.
  RAs = 0
  RAstring = Trim(Range(De).Value) & " "
  RAlength = Len(RAstring)
  pos = InStr(RAstring, " ")
  If (pos = RAlength) Then
   note = note & "Check R.A."
   RAcondition = "unusable"
  Else
   RAh = Val(Trim(Left(RAstring, pos)))
   RAmstring = Trim(Mid(RAstring, pos)) & " "
   RAmlength = Len(RAmstring)
   pos = InStr(RAmstring, " ")
   If (pos = RAmlength) Then
    RAm = Val(Trim(RAmstring))
   Else
    RAm = Val(Trim(Left(RAstring, pos)))
    RAsstring = Trim(Mid(RAmstring, pos))
    RAs = Val(Trim(RAsstring))
   End If
   RAm = RAm + RAs / 60
   VRA = Val(RAh) + Val(RAm) / 60
   RAcondition = "usable"
   If (VRA >= 24) Then note = "check RA " & note
   If (Val(RAm) >= 60) Then noteM = "check RA " & note
  End If
  
  'Approx. Precession correction
  If (timetype = "") Then
  Else
   If (precescor = "pre") Then 'Don't Bypass Precession correction
    If (yr < 2026) Then epochdays = stdays
    If (yr < 1970) Then epochdays = stdays + 50 * 365 + 12
    If (yr < 1926) Then epochdays = stdays + 100 * 365 + 24
    prec = 50.249 * epochdays / 365.25 * pie / 3600 / 180
    axisprec = prec * Cos(23.44 * pie / 180)
    decr = VDec * pie / 180
    VRAr = VRA * pie / 12
    x1 = Sin(decr) * Sin(axisprec) * Cos(23.44 * pie / 180) + Cos(decr) * Cos(VRAr) * Cos(axisprec)
    adjRAr = Atn((Cos(decr) * Sin(VRAr)) / x1)
    If (x1 < 0) Then adjRAr = adjRAr + pie
    If (Location = 18) Then prec = 0
    'RA1r = VRAr - prec
    RA1r = adjRAr - prec
    RA1 = RA1r * 12 / pie
    RA1h = Int(RA1)
    RA1m = (RA1 - RA1h) * 60
    RAh = RA1h: RAm = RA1m: RAs = 0
    'Range(Re).Value = prec * 180 * 60 / pie / 15
    'Range(Re).Value = (RA1r - VRAr) * 180 * 60 / pie / 15
   End If 'End Bypass Precession correction
  End If
  
  If (RAcondition = "usable") Then 'Compare (Start Time - RA) with HA
   hc = 0
   m = (stm - RAm) - HAMn
   'Range(Re).Value = m
   If (m >= 60) Then m = m - 60: hc = 1
   If (m < 0) Then m = m + 60: hc = -1
   m = Round(m)
   h = (Val(sth) - Val(RAh)) - HAHr + hc
   'Range(Re).Value = h & " " & m
   'Compute for -HA also to check "e vs. w" error.
   hc1 = 0
   m1 = (stm - RAm) + HAMn
   'Range(Se).Value = m1
   If (m1 >= 60) Then m1 = m1 - 60: hc1 = 1
   If (m1 < 0) Then m1 = m1 + 60: hc1 = -1
   m1 = Round(m1)
   h1 = (Val(sth) - Val(RAh)) + HAHr + hc1
   'Range(Se).Value = h1 & " " & m1
   'Normalize hour and minute values.
   If (h > 0 And m < 0) Then h = h - 1: m = m + 60
   If (h < 0 And m > 0) Then h = h + 1: m = m - 60
   If (m >= 60) Then h = h + 1: m = m - 60
   If (m <= -60) Then h = h - 1: m = m + 60
   If (h >= 24) Then h = h - 24
   If (h <= -24) Then h = h + 24
   If (h > 18) Then If (m = 0) Then h = h - 24 Else m = m - 60: h = h - 23
   If (h <= -18) Then If (m = 0) Then h = h + 24 Else m = m + 60: h = h + 23
   'Range(Re).Value = h & " " & m & " " & hc
   'Compute for -HA also to check "e vs. w" error.
   If (h1 > 0 And m1 < 0) Then h1 = h1 - 1: m1 = m1 + 60
   If (h1 < 0 And m1 > 0) Then h1 = h1 + 1: m1 = m1 - 60
   If (m1 >= 60) Then h1 = h1 + 1: m1 = m1 - 60
   If (m1 <= -60) Then h1 = h1 - 1: m1 = m1 + 60
   If (h1 >= 24) Then h1 = h1 - 24
   If (h1 <= -24) Then h1 = h1 + 24
   If (h1 > 18) Then If (m1 = 0) Then h1 = h1 - 24 Else m1 = m1 - 60: h1 = h1 - 23
   If (h1 <= -18) Then If (m1 = 0) Then h1 = h1 + 24 Else m1 = m1 + 60: h1 = h1 + 23
   'Range(Se).Value = h1 & " " & m1 & " " & hc1
   'Print note to user if necessary.
   'If (h = 0 And 1 > Abs(m)) Then
   If (h = 0 And maxerror > Abs(m)) Then
    note = ""
   Else
    If (HAHr = 0 And maxerror > Abs(HAMn)) Then
    Else
     If (h1 = 0 And 2 > Abs(m1)) Then note = "check H.A. (e vs. w) " & note
    End If
    note = h & "h " & Round(m) & "m " & note
   End If
   
   'Convert angle units to radians
   RAr = VRA * pie / 12: decr = VDec * pie / 180: Latr = Lat * pie / 180: HAr = VHA * pie / 12
   tstartr = tstart * pie / 12: tstopr = tstop * pie / 12
   
   'Compute Altitude Angles:
   'For Start Time
   SinAA = (Cos(RAr) * Cos(tstartr) + Sin(RAr) * Sin(tstartr)) * Cos(decr) * Cos(Latr) + Sin(decr) * Sin(Latr)
   'Arcsin(X) = Atn(X / Sqr(-X * X + 1))
   AA = Round(Atn(1 / Sqr(1 / (SinAA * SinAA) - 1)) * 180 / pie, 2)
   'Print Results
   If (Left(Trim(Range("Q1").Value), 3) = "Alt") Then
    Range(Qe).Value = Str(AA) & Chr(176)
    If (AA >= 0 And AA < AltL) Then Range(Pe).Value = Str(AA) & Chr(176) & " Low Angle"
   End If
   If (AA < 0) Then noteM = "Below Horizon at Start  " & noteM
   'For Stop Time
   SinAA2 = (Cos(RAr) * Cos(tstopr) + Sin(RAr) * Sin(tstopr)) * Cos(decr) * Cos(Latr) + Sin(decr) * Sin(Latr)
   AA2 = Sgn(SinAA2) * Round(Atn(1 / Sqr(1 / (SinAA2 * SinAA2) - 1)) * 180 / pie, 2)
   'Print Results
   If (Left(Trim(Range("R1").Value), 3) = "Alt") Then
    Range(Re).Value = Str(AA2) & Chr(176)
    If (AA2 >= 0 And AA2 < AltL) Then Range(Qe).Value = Str(AA2) & Chr(176) & " Low Angle"
   End If
   If (AA2 < 0) Then noteM = "Below Horizon at Stop  " & noteM
  End If
 End If
End If

'Report messages
'Range(Ie).Value = noteI & Round(exposuretime * 60)
Range(Le).Value = note
Range(Me1).Value = noteM

'Reset variables to check the next Plate data
noteI = ""
note = ""
noteM = ""
lastdate = pagedate
Next e

'Display final Message
'"All the information in these columns except the time type will be deleted after you have" & Chr(13) &
Message = MsgBox("Have you finished checking the logbook data?" & Chr(13) & "Answering yes will delete all the information in columns L through R that are in use (except the time types in column N)." & Chr(13) & "Answer yes after you have finished correcting any typing errors and noting any significant problems in the logbook data.", 4 + 256, "Logbook Data Test Completed")
If Message = 6 Then
 'Clear Columns
 Columns("L:M").Select
 Selection.ClearContents
 If (Trim(Range("N1").Value) <> "") Then Columns("O:P").Select
 If (Left(Trim(Range("Q1").Value), 3) = "Alt") Then Columns("O:R").Select
 Selection.ClearContents
End If
End Sub