A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Sean C
Date: 2021 Nov 23, 14:27 -0800
Here are the formulas my spreadsheet uses (per Meeus). Should be easy enough to implement these in VB.
E = L0 - 0.0057183° - α + ΔΨ · cos ε
... where E is the equation of time, L0 is the Sun's mean longitude, α is the apparent right ascension of the Sun, ΔΨ is the nutation in longitude and ε is the obliquity of the ecliptic.
L0 = 280.4664567 + 360007.6982779τ + 0.03032028τ2 + τ3 / 49931 - τ4 / 15300 - τ5 / 2000000
... where τ is the time measured in Julian millennia (365250 ephemeris days) from J2000.0 = JDE 2451545.0
L0 should be reduced to the range of 0° to 360°. L0, α and ΔΨ should be expressed in degrees. The equation of time will be expressed in degrees and can be converted to minutes of time by multiplication by 4.
You can also have a look at how it is implemented in my spreadsheet. Hope that helps!