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Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki

Ursa Astronomical Association

Alphonsus and Alpetragius - 9.5.2022 at 23.05 - 9.5.2022 at 23.20 Vantaa, Pähkinärinne Observation number 106706

Visibility III / V

Paula Wirtanen, Ursa (Helsinki)

A small, thin cloud was in front of the Moon and at first I wondered if the detection would be anything at all. Well, it came from it, even though the contrast was a little worse than a clear sky. The smallest details were not visible, but the Moon was still worth admiring for a longer time. Clavius was still in the shadows at the terminator and was the finest and most eye-catching target on the Moon. Similarly, Tycho stood out nicely and in addition to these I also took a photo of the Straight Wall .

However, I feel like I haven’t quite perceived the Moon unless I’m drawing something on paper and taking other notes in addition to taking a photo. Now the object of the drawing would be the middle crater of the Ptolemaic trio, Alphonsus.

Alphonsus is known for its dark spots at the bottom (L47), which are dark-circled craters. They are suspected to be of volcanic origin. So: would they show up? The photos are easy to get and stand out a little closer to the terminator, even visually.

The central mountain of Alphonsus stood out clearly as a bright nod, and the Alpetragius next to it looked quite nice. And yes: as time went on, these dark spots stood out pretty clearly. The darkening of the western edge was distinct, slightly triangular. The darkening of the eastern edge was somewhat paler and it was already a little pinched.

The dark areas I see are marked on the drawing with arrows.

When the observation was made, there was also a quiet murmur from somewhere in the legs. Well, that's where the leech went. Yes, the hedgehog took its feet under it and went into the bush quite quickly when it was noticed and unfortunately I did not have time to get a picture of that great little shot.

Yes, spring is starting to get pretty cool despite the beginning of May.

#Lunar100: 047 Alphonsus Dark Circle Craters.

Additional information
  • Observation target
    • Moon surface feature
  • Name of the observation target
    • Alphonsus ja Alpetragius
  • Seeing
    • Average
Technical information

Sky-Watcher Skymax-127 (M127 / 1500), 10 & 6 mm. Derwent HB.

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