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Plato and Vallis Alpes


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With an image of such magnitude it is difficult for me not to comment on the two targets that stand out the most; Plato and Vallis Alpes.
Plato is one of the main targets of lunar astrophotography.
A good photo of Plato should show at least 3 or 4 smaller craters present on its floor, always in a darker hue than the surrounding terrain.
But every good self-respecting atrophotographer knows that it's not easy to make these small craters appear on your floor and, for that to happen, certain conditions must be met.
Firstly, an opening of no less than 250mm is ideal, not that it is impossible to register them with 200mm or even 180mm, but with 250mm it is much easier.
Secondly, the angle of incidence of sunlight must also be observed, if the terminator is too low and close, the contrast is too great making it difficult to record, if on the other hand the sun is too high, the smaller craters do not form shadows which it also makes it impossible to register them. I believe that the ideal is the Sun at an altitude of 30° to 45° so the contrast is not so great and shadows are still formed, facilitating their perception.
Thirdly, we must pay attention to seeing, with a bad seeing any recording is almost impossible, as these small craters disappear when the turbulence is strong.
I won't talk about focus because any mistake destroys a good result!
As a general rule, in order to get an impressive photo of at least some of these small craters, they would have to be visible briefly during the real-time screen capture on the lap top. If so, we learned that after the best stacked frames, these small craters will show up perfectly as seen in the attached photo.

Vallis Alpes, in the south of Mare Frigoris, not far from the Cassini crater and Plato's Great Eastern Plain, is one of the most spectacular valleys on the moon.
Seen in this image, Vallis Alpes (Alpine Valley) is a feature that extends 166 km from Mare Imbrium, running northeast to the edge of Mare Frigoris. This valley was discovered in 1727 by Francesco Bianchini. The valley is narrow at both ends and widens in the center to be about 10 kilometers in diameter.
The bottom of the valley has a flat, lava-flooded surface with a narrow 'channel' winding through the middle. This channel is generally thought of as a "graben", an area between two parallel faults that have fallen below the surrounding area. The narrow inner channel is believed to have been formed after the formation of the Imbrium basin, after the lava flows into the sea. It probably corresponds to a 'lava tube' that collapsed in a later geological episode due to the high velocity and low viscosity of the magma.
Very interesting to know that channels are common on the moon, considered one of the most fascinating volcanic features due to their wide range of scales (from 100 meters to over 100 km in length) and morphologies they present (linear, curved or sinuous). 🇧🇷
Channels typically form when lava flows erode the existing surface, melting the substrate, removing mechanical material, or a combination of thermal and mechanical processes. However, some may have been lava tubes, rilles, that suffered roof collapse after their formation.
Trying to detect this relatively narrow and winding channel that runs along the bottom of Vallis Alpes is one of the favorite challenges of lunar observers, its exact dimensions are not exactly determined, but its vision is a very satisfactory test, as are the small craters on the floor. Plateau.
I hope these tips are of some use to anyone like me who likes to venture into Lunar photography!


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15 hours ago, astroavani said:

With an image of such magnitude it is difficult for me not to comment on the two targets that stand out the most; Plato and Vallis Alpes....

What an astonishing, mesmerising image.   The detail is incredible!


I am also a 'craterlet' fan, in the 8" and with poor UK seeing I can locate craterlet A quite easily and sometimes craterlet B with a little more patience.   C & D can be challenging from my location unless the seeing is very good.

Many of us observe  / image during waxing phase.  I am thinking of changing tactics and observing during waning phase, this would mean an early morning from here but the seeing may be better at that time.   Did you image this during waxing or waning phase?

Thanks Steve

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11 hours ago, Alkaid said:

Que imagem surpreendente e hipnotizante. O detalhe é incrível!


Eu também sou um fã de 'craterlet', no 8 "e com visão ruim do Reino Unido, posso localizar a craterlet A com bastante facilidade e, às vezes, a craterlet B com um pouco mais de paciência. C & D pode ser um desafio da minha localização, a menos que a visão seja muito boa .

Muitas de nós observamos/imagem durante a fase de depilação. Estou pensando em mudar de tática e observar durante a fase minguante, isso significaria uma manhã cedo daqui, mas a visão pode ser melhor naquele momento. Você imaginou isso durante a fase crescente ou minguante?

Obrigado Steve

Crescent my friend Steve

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Superb image! Thanks for sharing.

For comparison, here's an image I took of the Alpine Valley in an 8 inch Meade SCT taken in excellent seeing earlier this year - maybe the illumination wasn't ideal as the central rille is much less distinct.


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