About the Local Circumstances Calculator
Author: Bill Kramer
Last update: Saturday, 18-Apr-2015 09:57:07 EDT
About the Local Circumstances Solar Eclipse Calculator
The map shows the eclipse path across the Earth. The path at sea level is shown by a red line with green lines depicting the northern and southern limits of totality. The dot marker indicates a specific position or location.
Locations can be selected from a list. These locations are pre-stored in the program and are intended to simply show key points or cities along the path of totality. Input your location by either manipulating the dot marker on the map with the pointing device, selecting one from the list, or by typing in the coordinates directly.
You can enter latitude and longitude in degrees/minutes/seconds, degrees/minutes, or just degrees. Decimal places are allowed. For example, the value 10 degrees, 12 minutes, 45 seconds can be input as 10d 12m 45s, 10d 12.75m, or 10.2125 d.
UT is coordinated universal time. Enter the number of hours (+/-) from UT to your local time zone. Pre stored locations already have the UT offset stored. Set the UT offset to zero for results in UT.
Lunar Limb Profile analysis is included in the calculations. The position of the moon and its orientation towards the observer are taken into account to obtain a detailed profile. The profile is compared again the position of the Sun to find the valleys and peaks along the edge that will contribute to Baily's Beads.
When the Do the Calculation button is pressed thousands of computations are performed to determine the exact contact times for the location you supply. These contact times are displayed on the map as the page is regenerated. To the right you will find a figure showing Baily's Beads at one tenth of a second (you can adjust the time offset) before (and after) the primary contacts for totality. After the calculations have been run other eclipse chaser resources for the location just calculated are made available such as a count down timer and Lunar Limb Profile graphics.
The Solution at dot marker shows the result of a quick calculation for duration and time at central eclipse (or partial coverage information) for the current dot marker position. Move the dot marker by picking a point on the map or dragging it there. The duration computation does not include the center of figure, lunar limb correction, and astronomical refraction used when the Do the Calculation button is pressed.
Select a different eclipse path has a list of the solar eclipses known to this program. Additional solar eclipses can be added by request. Eclipse names that start with an "A" are annular eclipses. "E" names are total solar eclipses. Eclipses are listed by year and month abbreviation. To select a different eclipse, pick it from the list and press the Select button.