User Manual for
Lunar Calendars and Eclipse Finder
The Lunar Eclipse of 33-04-03 JC
Examples will now be given involving a search for eclipses.
First, suppose one wishes to find the time of the first lunar eclipse visible in Jerusalem in the year 33 JC. The longitude of Jerusalem is about 35 degrees 24 minutes East, so true local time is GMT + 2.35 hours, i.e., GMT + 2:21. The closest local time setting allowed by the software is GMT + 2:30, so we set it to this.
Then one enters "33-01-01 JC" into the Date/time box:
Pressing the 'Enter' key or clicking on Convert produces:
One now tells the software that one wishes to search for the next lunar eclipse:
Clicking on Search produces:
From which we may conclude that a partial lunar eclipse occurred on Friday the 3rd of April, 33 JC (April 1st, 33 CE), with the penumbral phase beginning at about 14:22 and lasting until about 19:54, and the umbral phase beginning at about 15:43 and lasting until about 18:32.
We can refine this slightly, since, as noted above, true local time at Jerusalem is not exactly GMT + 2:30. Since true local time is GMT + 2:21, the calculated times for the above eclipse should be adjusted by -9 minutes, giving: penumbral phase began at about 14:13 (true local time) and lasted until about 19:45, and the umbral phase began at about 15:34 and lasted until about 18:23. Thus the umbral phase would be ending at about the time the Moon appeared over the horizon.
It should also be noted that the value of delta T used by the software for 33 JC is subject to an uncertainty of a few minutes, so we should conclude only that the umbral phase ended in the period 18:20 to 18:28 true local time.
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