NavList:

Stan,

You wrote:
"After years of having been taught, thinking, and teaching that the Increments and Corrections table at the back of the Nautical Almanac is the same year after year, I have discovered that this is not the case. "

Fascinating! And bizarre, too. Just to clarify, you have found just those two instances so far, and they only differ by one tenth of a minute of arc. Is that correct? I realize two cases is a small set to judge from, but is there any pattern here at all? Are they 'edge cases' which might be prone to a small round-off difference?

I would imagine that someone decided to re-calculate the tables at some point because they had not been re-calculated since the adding machine days of the 1950s. Just speculating, perhaps around the year 2000 someone spotted a more substantial typo in that deep sea of numbers, and the folks at the Nautical Almanac Office realized that they might as well just code it up and re-do the whole table (since re-calculating the whole thing in the 21st century is undoubtedly cheaper than a manual check of all the numbers as previously printed). More cynically, the tables may have been re-calculated merely to justify the existence of certain positions at the NA Office.

And the date of this change is before the minor change in the refraction table which you and your eagle eye brought to the attention of NavList many years ago, right?

-FER

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