Lunar 100 observing report 22.4.2010

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22.44.2010

Meade lightbridge 16" F4.5 FL 1829mm

Estimated seeing was 2.5/5

Phase 75.4°

Lunation 8.33 days

Illumination 62.6%

Alphonsus dark spots Number 47

Following on from yesterdays observations of Alphonsus where the whole of the basin floor was covered in darkness, tonight it was bathes in sunlight, I could easily detect three dark halo eruptions on the crater floor through my 9mm ortho, they were situated near the edge of the craters steep walls and were 120° from each other, they looked very small maybe 4 miles in diameter and were of circular formation.

Plato Number 83

Plato was formed in the Upper Imbrian (From -3.8 billions years to -3.2 billions years) period and is a very large crater at 61 miles in diameter and of unknown height, Plato looked fantastic in the 12.5 mm ortho at x146 I saw a complete ring of light bouncing off the cliff tops surrounding the crater, enormous jagged shadows cast on to the upper basin floor, very magical indeed. The Lunar 100 tells us to count the little cratlets on Plato's basin floor so with this in mind I inserted my 9mm ortho into the focuser and through this I could just detect just one cratlet towards the northern edge but the 6mm ortho split this cratlet into two and with prolonged seeing I could detect two more as well, bringing the total to four cratlets from x304 magnification. I'm sure if the seeing was better I could detect more.

Mösting A Number 61

Just west of Ptolemaeus lies Mösting a 16 mile diameter and 8400 feet high crater, nothing spectacular about it just a very nice circular crater but our destination is Mösting A which turns out to be alot harder to detect. It is a circular formation situated on the slopes of Flammarion. I needed the 6 mm ortho to actually pick out the formation but once you have detected the oval shape crater truncated to the north by Rima Flammarion it's quite easy to spot.

Sinus Aestuum Number 79

A very flat looking plain from the Pre-Imbrian (From -4.55 billions years to -3.85 billions years) period bordered to the SE of Eratosthenes, to the north by the Wolfe Mountains, and to the East by Rille Bode. The plains include a rather distictive wrinkle edge in the SE corner. I could detect ejecta deposits at the base of Eratosthenes. Also through my 6mm ortho I could only just detect a darkening of the floor around the wrinkle edge between the craters Bode H anf Bode C.

Rupus Recta Number 15

I have seen this one on numerous occasions and it must be the most famous and observed lunar feature, it is actually a gentle slope not a wall and is 67 miles long and has a gradient of 40°. Through my 9mm ortho at x 203 it look fantastic, I could trace it's entire length, and the crater Birt A dominates near by. I could also detect the very small Rima Birt this geological feature is just 30 miles long and 1 mile wide. Moving further away from Rupus Recta is a very strange feature that resemble a snake coming out of the crater Nicollet, it's unamed on VMA but in my mind it really looked like a wriggling snake on the lunar surface.

Pitatus Crater with concentric rilles Number 84

Situated on the south shores of Mare Nubiam is a circular formation crater called Pitatus through my 9mm ortho I could see an off centre peak with terraced like sides making the impression of rilles inside the crater, I could detect these around at least 60 % of the craters circumference. Loads of little cratlets around the outside a very interesting crater with so much to observe at a later date. Pitatus is 59 miles in diameter and of unknown height, it comes from the Nectarian (From -3.92 billions years to -3.85 billions years) period in the moons history.

Tycho Number 6

What a fantastic object to observe Tycho is a large circular formation crater from the Copernician (From -1.1 billions years to present days) period and is 52 miles in diameter and very high at 14500 feet. Through the 9mm ortho it looked stunning and is perfectly round with very steep sides I could see how steep they were due to the angle I was viewing Tycho from. Very deep floor engulfed in blackness but the central peak was bathed in sunlight as was the surrounding walls. The best view of this crater was through my 6mm ortho at x304 I could actually sense climbing the outer cliffs, they were that clear and looked that near.

Clavius Number 9

The highlight of the night due to the angle I was viewing from has to be Clavius, this is one very steep and large crater at 136 miles in diameter. I could only see half of it as the rest was in the blackness of the terminator. The whole floor was bathed in darkness except for the rims of Clavius C & D which were bathed in sunlight. A very magical moment and one I will return to when the terminator has moved on.

[jgs001]

Excellent report Mick, you're pressing on with the 100 nicely. I spotted Clavius just as you described, an amazing sight (although I was looking at it on a lappy screen, not through the ep)

[DarkerSky]

Clavius is one of my favourites. Super descriptions of what you saw. I'm feeling inspired !!