What is the difference in altitude angle (in arcseconds) of the Sun's upper limb as observed from two locations on the Earth's surface during a total solar eclipse: Location 1: latitude 40.7128° N, longitude 74.0060° W, elevation 10 meters, at 14:45 UTC on August 21, 2017 Location 2: latitude 34.0522° N, longitude 118.2437° W, elevation 50 meters, at 14:45 UTC on August 21, 2017?