The Sun Solar System: the Moon Planets observing logs

March 29th, 2004: Lunar observing log

1. Overview of the 8-day-old-moon

I always start my observing session with the lowest magnification possible, just to see which features look most interesting for a more detailed study. Tonight I immediately noticed the three mountain chains to the east of Mare Imbrium. From north to south I could see the Montes Alpes (Rukl 4), the Montes Caucasus (Rukl 13) and the Montes Apenninus (Rukl 22). Further to the south is an interesting chain of three big craters visible: Ptolomaeus, Alphonsus and Arzachel (Rukl 44 and Rukl 55). I decided to observe these areas more detailed. I would end my observing session With Rupes Recta, the straight wall.

Image 1: overview of an 8-day-old moon

2. The north and the three mountain chains

North of Mare Frigoris (Rukl 4) lies a big diamond shaped crater, W. Bond, with a diameter of 158 km. On the crater floor, near the eastern rim, I detected W. Bond B, a young impact crater with a diameter of 15 km. To the south of Mare Frigoris lie the Alps (Montes Alpes) with the well-known Alpine Valley (Vallis Alpes) at the northwestern edge of the Imbrium basin. The Vallis Alpes is about 180 km long, and on its flanks are peaks over 3000 meters high. The peak on the southern end of the Alps, located in the plains of Mare Imbrium, is the Promontorium Agassiz (Rukl 12). To the southeast of this peak lies the Crater Cassini, and to the southwest we find Mons Piton, an isolated mountain, 2250 meters high, with a base of 25 km. As you can see on the image below, tonight the eastern flank of Mons Piton is lit by the Sun. To the east of Cassini lie the Montes Caucasus (Rukl 13), with Mare Serenetatis to the east and Mare Imbrium to the west.

To the south of the Montes Caucasus lie the mighty Apennines (Montes Apeninnus, Rukl 21/22) with peaks over 5000 meters. The Montes Apenninus are a part of "the wall" around the Imbrium basin. To the west of the mountain chain lies the big lava-flooded crater Archimedes (Rukl 22) with the Montes Archimedes clearly visible to its south. To the northeast of Archimedes lie two craters, Aristillus and Autolycus.

Image 2: The North and the three mountain chains

3. Ptolomaeus, Alphonsus, Arzachel and Rupes Recta

On the southern half of the moon lies a chain of three craters. I started with the biggest (northernmost) of the three, Ptolomaeus (Rukl 44). This crater has a diameter of 153 km. It is also the oldest of the three craters you see on the image below. On the northern rim of Ptolomaeus you can see a smaller crater, Herschell. South of Ptolomaeus lies Alphonsus with its central peak of 1100 meters high.

The southernmost of the three craters is Arzachel (Rukl 55), named after Al Zargali, a Spanish Arabic astronomer (about 1028-1887). Tonight I was able to detect a part of the Rimae Arzachel between Arzachel A, the crater northeast of the central peak, and the edge of the crater. Arzachel K is visible south of Arzachel A. In the western rim of the crater, Arzachel B (a small crater) and Arzachel F (a kind of valley) are visible. The base of the central peak is 11 x 29 km and the peak reaches a height of 1500 meters.

To the west of Arzachel the eastern edge of Mare Nubium can be seen. The most striking feature tonight is Rupes Recta (Rukl 54), or the Straight Wall. This feature is not really a vertical wall, but a 110 km long gentle slope, about 250 to 300 meters high. At the northern tip of Rupes Recta you can see Promontorium Taenarium, a cape lying in Mare Nubium. To the west of Rupes Recta, the craters Birt and Birt A are visible. When you examine the image closely you can see the 50 km long Rima Birt, starting just to the west of Birt, and from there going in north north-western direction.

Image 3: Ptolomaeus, Alphonsus, Arzachel and Rupes Recta

Equipment used:

I observed from my backyard, using the f/10 2000mm TAL 200K Klevtzov-Cassegrain, a 32 mm televue plossl eyepiece, and a series of Vixen Lanthanum’s ranging from 25mm to 7 mm. I did not use any filters. I made some digital images, using the Nikon Coolpix 4500 with a Nikon remote control and two ScopeTronix adaptors to connect the camera to the eyepieces. I shot all the image using the S mode (Shutter Priority Auto). In this mode you can only change the exposure time. The camera adjusts the aperture automatically. The flash was switched off. All images are stacked out of multiple images using Keith’s Image Stacker (Mac). The stacked images are processed (rotate, unsharp masking, auto color) using image processing software.Most images are oriented with North up and West to the left, as in the Rukl Moon Atlas.

Copyright © 2004