Download or view mithengereverse.frink in plain text format
use sun.frink;
use mithengecorridor.frink;
// Reverse-engineer MIThenge observations by Ken Olum on 2005-01-31:
// "At 4:52:36 I found that the left limb of the sun lay on a line from my
// eye at the left edge of the corridor to the left edge of the
// doorframe. This part of the sun had set behind the hill by this time,
// so this was an extrapolation by completing the circle from what I
// could see."
//
// Ken provided better measurements of these points later. He added:
// "My observation against the left edge of the corridor was not to the
// doorway but to the 2'1" narrowing, which blocked my view of the
// doorway."
// See diagram at http://cosmos.phy.tufts.edu/~kdo/corridor.jpg
date = # 2005-01-31 04:52:36 PM Eastern #
println[date -> Eastern]
// Calculate the sun radius at this time.
sunRadius = sunRadiusAngle[date]
println["Sun radius is " + (sunRadius -> "degrees")]
// Temperature and pressure figures are as measured in Cambridge for this
// date and time.
[sunAzimuth, sunAltitude] = refractedSunAzimuthAltitude[date, lat, long, F[29], 30.42 inHg]
// Horizontal distance from left edge of 2'1" narrowing
// (With no offset; Ken said that his eye was even with the wall in a stairwell)
h = 2 feet + 1 inch
// Distance to narrowing
d = 279 feet
// The angle added to the centerline of the corridor
angleOffset = arctan[h,d]
println["Angle offset is " + (angleOffset -> "degrees")]
// Convert Meeus azimuth conventions to normal conventions.
sunAzimuth = (sunAzimuth + 180 degrees) mod circle
println["Sun center azimuth is " + (sunAzimuth -> "degrees")]
sunLeft = sunAzimuth - sunRadius
println["Sun left azimuth is " + (sunLeft -> "degrees")]
corrAzimuth = sunLeft - angleOffset
println["Corridor azimuth is " + (corrAzimuth -> "degrees")]
Download or view mithengereverse.frink in plain text format
This is a program written in the programming language Frink.
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Alan Eliasen was born 19971 days, 5 hours, 32 minutes ago.