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Re: Quick refraction rule
From: Frank Reed
Date: 2025 May 16, 13:47 -0700
From: Frank Reed
Date: 2025 May 16, 13:47 -0700
Thanks to Chuck Varney for spotting a little typo in my original post on this! I very carefully checked that post since I have been stung by this as an arithmetic error more than once. But this time around, transcribing from my perfect original notes on the case in question, I committed a damn typo. Grrr... Shame on me. And shame on the rest of you all reading this for not spotting it. :)
What was that typo? Go back and read the original post which I have edited to remove the typo and leave a tiny hint of its former location.
To emphasize again, the short rule for refraction is dirt simple: r'=z°/50 down to an altitude of nearly 45° (and it's only out by a tenth of a minute of arc for a few more degrees after that).
Frank Reed
