Circumstances window
This window gives the circumstances of the eclipse for the selected location. In everyday language, that means many informations about times, location in the sky of remarkable events in the eclipse progression, whether the eclipse is partial or total and more. It will be detailed hereunder.
The "Update" button refreshes the window with the circumstance for the eclipse selected in the
"elements" window and the location selected in the
"location" window. When the location is locked on a GPS receiver, this window is refreshed continuously.
The remarkable events of an eclipse are called "contacts" :
- The first contact is when the moon's and sun's disk start intersecting, this is the beginning of the partial phase.
- The second contact is when the moon's disk first totally covers the sun's disk for a total solar eclipse, or when the moon's disk is entirely inside the sun's disk for an annular eclipse. It is the start of the "central" phase (also called totality for a total).
- The maximum is when mon's and sun's centers are nearest,
- The third contact is when the moon's disk ends covering totally the sun's disk for a total solar eclipse, or when the moon's disk end being entirely inside the sun's disk for an annular eclipse. It is the end of the "central" phase, the eclipse becomes partial again.
- The fourth contact is when the sun's and moon's disks intersect no more. This is the end of the eclipse.. when you start thinking of the next one!
The informations displayed in this window are :
- Current date and time given by the computer or the GPS receiver ; alternatively, during rehearsal of a scenario, this is the simulated time controlled by the "action" window.
- Time before the next "event", given in days, hours, minutes and seconds,
- For each event :
- date and time,
- altitude and azimuth in the sky.
- In addition, for contacts :
- position angle, in degree, of the contact on the sun's disk relative to celestial north,
- position angle of the contact, in hours, relative to the zenith.
- The eclipse type : Partial, Annular, Total or no eclipse at all,
- The duration of the central phase, if any,
- The maximum coverage of the moon's disk over the sun (100% if total),
- The magnitude of the eclipse, that is the ratio of the moon and sun apparent sizes,
- Umbral,Antumbral depth represents how far your location is in the (ant)umbra, 100% means that you are on the centerline,
- Distance and bearing of the nearest point on the centerline : go this way to maximize your eclipse duration,
- Latitude and longitude of the nearest point on the centerline,
- Loss of total phase duration at your current location with respect to the nearest point on the centerline, with this information, you can decide if it worths to relocate your observing site.