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")]