(formerly Wollaston C)
Lat: 31.78°N, Long: 51.75°W, Diam: 9.64 km, Depth: 1.96 km, Rükl: 8
The vaguely depicted wrinkle ridge at "Eleven O'Clock" from crater Nielsen is just the southern part of the very pronounced (officially unnamed) Dorsum which runs all the way to the north-northwest, toward Mons Rumker. It would be interesting to call this pronounced wrinkle ridge Dorsum Nielsen-Rumker.
- AS15-88-11983 shows bowl-shaped crater Nielsen and the pronounced (and officially unnamed) dorsum north-northwest of Nielsen, which runs toward Mons Rümker. The curious bluish shape in the photograph is an internal reflection on one of CSM Endeavours (or LM Falcons?) small windows. Research: David Woods (Apollo 15 Flight Journal) and - DannyCaes Nov 26, 2007
- IAU page: Nielsen
- Depth data from Kurt Fisher database
- Westfall, 2000: 1.96 km
- From the shadows in LO-IV-158H, Nielsen is 1780-1900 m deep. - Jim Mosher
- A curious "8"-shaped (or Peanut-shaped) craterlet (a system of two connected craterlets with high rim) is located west-northwest of Nielsen. This "8"-shaped feature is described and depicted in NASA SP-362 Apollo Over the Moon, Chapter 4: The Maria (Part 3), Figure 89. Note: the photo-number which is mentioned below the depicted photograph (in AOTM) should be 10344, and not "0344"! Research: Danny Caes
- The curious Peanut-shaped craterlet (NW of Nielsen) is also noticeable near the upper right corner of Lunar Orbiter 4's Frame 163-H1. Research: Danny Caes
- According to the IAU Planetary Gazetteer, this crater name honors two individuals:
- Axel Vilfrid Nielsen (December 13, 1902 - February 24, 1970), a Danish astronomer. In 1921, while still a student, Nielsen established his private observatory "Spica" in Glostrup. The observatory was located on the premises of a local enterprise, where Nielsen's father was employed as a manager. In 1927 Nielsen was employed as an assistant with the Ole Rømer Observatory. Nielsen published several books and articles on astronomy and the history of astronomy in Denmark. In 1944 he published a major work on the Danish astronomer Ole Rømer (1644-1710).
- Harald Herborg Nielsen (1903 - January 8, 1973); an American physicist born to Danish parents. He was noted for his contributions to molecular spectroscopy.
- Wollaston C, the former name attributed to Beer and Mädler, had been Catalog number 1739 in the Collated List and Named Lunar Formations.
- Nielsen, for this feature, appears in the list of approved names published in IAU Transactions XVB (1973). The new honoree is not identified, but biographical information (identifying only "A. V.") was unofficially reported in Ashbrook, 1974.
- The replacement name was first used on LTO-38B2 (September 1975), for which it served as the chart title.
- The association of the name with the present honorees is based on listings in early versions of the IAU Planetary Gazetteer. When "H. H." was added is unclear.
- The pronounced dorsum which runs north-northwest of Nielsen, toward Mons Rümker, is unofficially called "Dorsum Nielsen-Rümker" by - DannyCaes Nov 26, 2007
- Wollaston Epsilon (the small hillock west of Nielsen).
- Nielsen's Keyhole, Nielsen's peanut, Nielsen's "8" (three nicknames from D.Caes for the curious elongated double craterlet northwest of Nielsen). See also http://bit.ly/2uIqu06 for the pinpoint location of it in the LROC ACT-REACT QUICK MAP.