News Circular 203 - June 1998
"Observers with an eye for detail"
Grahame Wheatley (Long Eaton, Nottingham) continues to make very detailed and accurate lunar observational drawings using a 125 mm refractor and 300 mm reflector. His most recent studies include: Aristoteles & Mitchell (17 Feb); Cleomedes (1 Mar); Theophilus, Cyrillus 8c Catharina (4 Mar); Copernicus (7 Mar); Milichius & Milichius Pi / Mons Vinogradov (both 8 Mar); Montes Harbinger, Prinz & Kreiger (9 Mar); Hevelius (11 Mar); Julius Caesar region (19 Mar); Brown & Brown E / Ptolemaeus, Alphonsus & Arzachel (both 20 Mar); superb study of the Alps, Alpine Valley & Mt Piton / Eratosthenes (both 5 Apr); Mare Humboldtianum (northeast limb) / Mare Marginis (east limb) / Hortensius & dome field / Montes Recti (all 6 April); Montes Harbinger & Dorsum Bucher (7 April).
Using his 150 mm Maksutov telescope, Nigel Longshaw (Chadderton, Oldham) is another highly competent member who makes technically superb observational drawings, specialising in stippling with ink dots to convey shade and tone - a technique in which he is unrivalled. His drawing of the Gay-Lussac region (6 April) to the north of Copernicus shows intricate detail on the crater floor, including tiny craterlets that were undoubtedly produced from the fallout of the Copernicus impact some 900 million years ago.
In his drawing of the Wichmann area (7 April), Nigel concentrates on a somewhat neglected corner of Oceanus Procellarum that will give up its secrets only to the patient observer at a suitable illumination. Here, Nigel notes the presence of an ancient flooded crater, numerous hills, craterlets and the presence of low ridges very close to the terminator. Nigel points to evidence of ancient lunar vulcanism,especially noticeable on Apollo 16 mapping camera frame 2838. The lava flows of Oceanus Procellarum erupted about 3,200 million years ago. By a remarkable coincidence, Nigel has also sent an observation of the Montes Harbinger and Dorsum Bucher, made on 29 Feb 1996, at an almost identical illumination as Grahame Wheatley's observation of the very same features on 7 April 1998. I also captured part of this region in a drawing made on 10 November 1997.
Because of a host of reasons it can prove a frustrating exercise to put different observers of the same feature next to each other in an attempt to make direct comparisons. Even observations of the same feature, made under similar lunar lighting conditions with the same telescope by a single observer can appear at inexplicable odds with each other. However, after comparing Nigel and Grahame's drawings it can be deduced that the two observers are both accurate and unambiguous in their recording skills.
This is an area on the border of Mare Imbrium and Oceanus Procellarum. The large triangular assembly of mountains in the north is unnamed on Rukl's lunar map (HamLyn AtLas of the Moon, 1990). The mountain group, probably a remnant of the original Imbrium ramparts that were buried by lava flows, occupy an area equivalent to the Isle of Wight. Here they cast spire-like shadows onto the plain. Further to their west, and flowing south across the mare, a series of wrinkle ridges called the Dorsum Bucher and Dorsum Argand lead to the Harbinger mountains, another remnant of the buried ancient western Imbrian border. This is a geologically fascinating area of the Moon that will repay close scrutiny through a telescope of any size. Indeed, the Aristarchus area to the west of Montes Harbinger is one of the Section's Special Topographic Projects - if you're interested in doing lunar research, send SAE for map and details.
