FreeLists / az-observing / [AZ-Observing] Fra Mauro and friends

["Steve Coe" <stevecoe@xxxxxxxxx>]

Hello all;

At sunset the thick clouds over Phoenix made it look like there would be no 
viewing tonight.  But, by 8:10 the clouds and thinned and a "ring around the 
Moon" was prominent.  I have seen these conditions yield some good views 
before, so I rolled the roof back and turned on the fan in the 7 inch f/15 
Maksutov and let it cool down for a while.

I put in a 15mm Panoptic eyepiece just to see what was on the terminator and 
was immediately struck by Guericke, this large crater has three prominent 
craterlets on the south side and its walls are ruined to the north.  There are 
several places where hills trail off the wall of this crater and those hills 
are perpendicular to the crater walls, I don't remember seeing that anywhere 
else on the lunar surface.  To the north of Guericke the two rows of hills form 
a set of parallel lines that are very prominent with the sun at this angle.  
Most of this smaller detail was seen with 12mm and 10mm Lanthanum eyepieces.  
The high clouds provided enough filtering that none were added at the telescope.

Moving north to Parry, it is an obvious flooded crater with a small double 
craterlet dead center.  Parry is the only crater in this area with a complete 
walled ring around it.  All the others are ruined craters.  Parry has a rille 
that runs along its western side and then turns east as it gets to the southern 
edge of the crater, somewhat like a giant letter "L".

Bonpland is to the west of Parry is only compete for about 100 degrees of arc 
along its northern lip.  Another rille passes through the center of Bonpland 
and there is a line of little craters that parallel the rille.  The craterlets 
are only held steady for about 30% of the time, they come and go with the 
seeing.

Fra Mauro is to the north of all of these craters and is the most ruined 
feature on the Moon that has received a designation that I know of.  It became 
famous when Apollo 14 landed near it in the early 70's.  The rille system from 
Parry and Bonpland combines to cut this crater in half.  The rille system is 
not quite as prominent here as it is as it cuts through Bonpland, but I can 
still see it most of the time.  The circular shape of Fra Mauro is most easily 
seen to the south, where is meets Parry.  On the north side it is almost 
completely missing, only a shadow of a few raised bumps in the surrounding area 
hint at former glory.

This is a fascinating region of the Moon that I have spent little time 
exploring in the past.  I got diverted to the Southern Highlands or Plato and 
Copernicus to the north.  Always something new to see.  I wonder how many 
people who have really spent some time observing the Moon would call it boring? 
 Not me.

Clear skies;
Steve Coe

stevecoe@xxxxxxxxx
Author:  Deep Sky Observing--The Astronomical Tourist
Saguaro Astronomy Club web site:
www.saguaroastro.org

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