A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2019 May 18, 14:05 -0700
The "fata morgana" was great indeed (ships' silhouettes floating in the air, shadow of the opposite shore, etc) but grander still was my own blunder! :)
Two things coincided:
- abnormal refraction (no less than 4~6 arcminutes)
- I started using TI-83 for HS corrections (full set of formulas for HoE, parallax, refraction by Bennet-1982), the last step was SD.
That huge "away" intercept was because I forgot to store the Sun SD value in a register...
Re-doing those SRs by hand and paper tables revealed that missing (SD) correction. The errors eliminated - the intercept became more reasonable - "4 away".
The lesson I've learned from that story: never blindly trust what you read on a screen, always have your own estimation for the expected answer. I could have noticed that HO and HS do not correspond to the usual difference of a Sun LL sight.