NavList:

I found a slightly shorter approach to this  calculation. If you do the SD
correction after the parallax, the augmentation  cancels out. Here's the  code:

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kk = 180 /  3.141593

'Mean Horizontal Parallax:
HP0 = 57.7
'Ratio of Moon's  mean SD to HP0. Again, 0.2724 would probably
'be more acurate but this  matches the tables:
SDcon = .2711
'SD0 is the semi-diameter at the mean  Horizontal Parallax, HP0:
SD0 = SDcon * HP0

INPUT "HP:", HP

FOR  h1 = 0 TO 89 STEP 1
PRINT h1

'The observed  altitude, h1, determines the refraction
h2 = h1 - refr0(h1 / kk)  / 60

'Add in parallax and mean semi-diameter
h3 = h2 + HP0 * COS(h2 / kk) / 60 + SD0 / 60

'The Lower  Table uses the average altitude from the upper column:
havg =  2.5 + 5 * INT(h1 / 5)

'h4 (LL/UL) is the increment in the  Moon's semi-diameter and
'its parallax for the difference  between the actual HP and the mean
'Horizontal Parallax,  HP0.
dHP = (HP - HP0) / 60
dSD = SDcon *  dHP
h4 = h3 + dHP * COS(havg / kk)
h4LL = h4 +  dSD
h4UL = h4 - dSD

'To keep the Lower Table  corrections always positive, add
'5 minutes to the LL correction  and 35 to the UL correction.
'To compensate, subtract 5 minutes  from the Upper Table.
'Also subtract twice the mean  semi-diameter for the UL.
UTcorr = 60 * (h3 - h1) -  5
LTcorrLL = 60 * (h4LL - h3) + 5
LTcorrUL = 60  * (h4UL - h3) - 2 * SD0 + 35

'output the  results:
PRINT "Upper Table Correction:     ";
PRINT USING "###.##"; UTcorr
PRINT "Lower  Table LL Correction: ";
PRINT USING "###.##";  LTcorrLL
PRINT "Lower Table UL Correction: ";
PRINT USING "###.##"; LTcorrUL
IF LEN(INKEY$) THEN EXIT  FOR

SLEEP
NEXT
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-FER
42.0N  87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars 


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