Alphonsus, and Arzachel
South is up in this image, more info below.
Instrument: 12.5" f/5 with 1.8x Barlow
Platform: Astrophysics AP1200
CCD Camera: Image Source DMK 31AU03.AS
Filter: Hoya R72
Exposure: 1/60 sec 15fps
Location: Payson, Arizona
Elevation: 5150 ft.
Sky: Seeing Average, Transparency 8/10
Outside Temperature: 35F
Processing: Registax, PixInsight Pro, Photoshop CS3, Focus Magic Plugin
One of the finest crater trios on the near
side of the lunar surface is Ptolemaes, Alphonsus, and Arzachel.
(Bottom to Top). The amount of detail in this moderately high
resolution image is worthy of further discussion, and I'll start
with the big three, then you can work our way around this field.
And please take a look at the full sized image, the small thumbnail
above is merely a taste of the numerous details of this region.
Lets start with
the bottom most crater in this image, or more correctly Ptolemaeus
is a "Walled Plain". This is the most ancient crater
of the three, and you can see the walls of Alphonsus encroaching
on its south side where the two meet. Ptolemaeus is 92 miles
in diameter, the same distance of Payson to Phoenix. Along with
some ghost craters and tiny craterlets, the floor of this crater
is relatively featureless. Of special interest is the 10 mile
diameter half ghost crater Ptolemaeus B, located just below the
largest small crater in the lower left (NW) quarter. It is half
submerged in mare lavas.
Next, and in the
center of this image is Alphonsus. This 71 mile diameter walled
plain type crater contains a central peak, Also a series if ridges
runs in a north south direction through the crater. On the left
side, if you look carefully, you can find Rimea Alphonsus, a
collapsed lava tube like formation.
The smaller but
magnificent crater at the top of the trio is Arzachel. A very
deep crater, some 60 miles in diameter has 3000 foot rims, and
a 4000 foot tall mountain in the center. The floor of this lava
filled crater is very rough, and of special interest is the very
well defined rille on the left side, snaking round small craterlets.
The name of this beautiful structure is Rimea Arzachel.
Also of special
note, look at the numerous gouges in the landscape in a north
west - south east direction. These were blasted out when the
large crater Copernicus to the north east was formed.
best frames, MAP 50 alignment in Registax, Regulated Van Cittert
Deconvolution in PixInsight Pro, Levels and Contrast Masking
In Photoshop CS3, Focus Magic Plugin.