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Sun's SD to 0.01' (-ish) from Nautical Almanac
From: David Iwancio
Date: 2021 Jan 12, 03:57 -0800
From: David Iwancio
Date: 2021 Jan 12, 03:57 -0800
- Using GHA & dec. of the sun and GHA Aries (dec. of Aries is always 0), determine how much the sun has moved over 1 day
- Divide this distance by 59.136'
- Take the square root of this result
- Multiply by 15.987' to get the sun's semidiameter
I've just been bothered with having to go to outside the almanac to get this information and nothing jumped out from searching the archive.
Test dates from 2020:
- 02/02
- Formula: 16.20' *
- MICA: 16.23'
- Almanac: 16.3'(!)
- 03/25
- Formula: 16.03'
- MICA: 16.04'
- Almanac: 16.1'
- 05/01
- Formula: 15.87'
- MICA: 15.87'
- Almanac: 15.9'
- 06/24
- Formula: 15.75'
- MICA: 15.73'
- Alamanac: 15.8'
* 02/02's number comes out to 16.22' if I instead multiply by sin(15.987') and take the inverse sine of the result.
