A grazing occultation locally of the star Aldebaran late Saturday night March 4
Note: This post is for a very specific location in the northern lower peninsula of Michigan. The occultation of Aldebaran is visible from most of the United States except Alaska and Central America. For predictions for your locations you can use a planetarium type program like Stellarium, Cartes du Ciel (Sky Charts), which can be downloaded free from the right column on this blog page, or the commercial planetarium program of your choice. Make sure the program is zoomed in so the Moon is actual size, and set for your location, and play around with the time.
The file to load for this occultation map overlay is: http://ephemeris.bjmoler.org/ZC692-2017-Mar-5.kmz.
Saturday night just after 11 p.m. the upper right edge of the Moon will just cover the bright star Aldebaran, the angry red eye of Taurus the bull. That is for some of us. For those of us south of a line from Leland to just south of Mancelona and off across the state the Moon will occult or hide the star. For those north of that line Aldebaran will just miss the Moon. Start looking at 11 p.m. or so. The center of the occultation as it I called is about 11:13 p.m. The farther south of that line you are the longer the occultation will last. At 11 p.m. the star will be just off the upper right edge of the Moon.
Here's the legend for the labels:
# H M S (Mag)
#: 1 First contact, Aldebaran disappears
2 Middle of the occultation
3 Last contact, Aldebaran reappears
H: hour UT, 4 = 11 p.m. EST
Mag: Magnitude of the star, 0.9 (First magnitude star)
Late Saturday night March 4th the Moon will pass in front of, or not the bright star Aldebaran. The “or not" depends on where you are.
The event is called an occultation. The word comes from occult, which, despite its baggage, simply means hidden. When one celestial body moves in front of another and completely covers it an occultation occurs. In actuality a total solar eclipse is an occultation. However a lunar eclipse is still an eclipse as we see it, but an occultation as the Sun sees it.
Above there’s a map of the Leelanau and Old Mission peninsulas and a bit of the Lower Peninsula of Michigan with a line drawn across it from north of Leland to just south of Mancelona. That is the calculated northern limit of the occultation. Observers within a mile of so of that line could see Aldebaran winking in and out as it’s light encounters mountains and passes through valleys at the northern limb of the Moon.
Even though we’ve landed humans on the Moon and have mapping satellites orbiting it, there is still a need to add more data to the accumulated knowledge we have of the surface and position of the Moon. Observers in a coordinated effort can be set up perpendicular to the graze line and using coordinated time signals produce a map of the edge of the Moon.
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