(the following narrative, probably written by Ewen Whitaker, appears as Section I of NASA SP-241 )

I. A SHORT HISTORY OF LUNAR NOMENCLATURE


17TH CENTURY


The naming of the lunar craters, mountain ranges, and other features dates from the middle of the 17th century, when three distinct systems of nomenclatures were introduced by Langrenus (1645 ), Hevelius (1647 ), and Riccioli (1651). Langrenus used mainly the names of scientists, members of royalty and the nobility, etc. in his system; his map contains more than 300 features, every one of which is named. Hevelius did not follow his example, but likened the front side of the Moon to a map of Europe and adjacent portions of Asia and Africa, naming the lunar features after terrestrial counterparts. Riccioli, however, reverted to Lang­renus' system of using personal names, but restricted his selections almost entirely to astronomers, philosophers, and other scientists whose names at least were associated in some manner with the Moon. His system was well planned and consistent; not only were the names basically arranged in chronological order from the north limb to the south, but they were also grouped by nationality, interests, teaching, and the like, with the more important names being assigned to the larger and more prominent craters.

The widespread distribution of the maps of Hevelius and Riccioli, which were published within important folio volumes, completely eclipsed the limited production of Langrenus' single-sheet map. Therefore, that Lang­renus' nomenclature was never used is hardly surprising; the systems used by the two later astronomers soon gained universal acceptance and con­tinued for the next 140 years, by which time telescopes of improved per­formance and convenience had become reasonably available.

18TH CENTURY


A pioneer selenographer of the era of improved telescopes was an ama­teur, Johann Schröter, who charted much of the lunar surface in far greater detail than had been achieved before. His work soon demonstrated the inadequacy of both nomenclature systems then in use, because many prominent craters remained unnamed. In particular, Hevelius' system was found to be unsuitable because a single name frequently was assigned to an entire group of craters and because many names were inconveniently long. Schröter added more than 70 new names of astronomers and other scientists, as well as numerous subsidiary letter designations.

19TH CENTURY


The next milestone in the evolution of lunar nomenclature was reached with the publication of Beer and Mädler's map in 1834. This map, more than 3 feet in diameter, was based on a network of small craters and isolated hills, the selenographic positions of which were determined by measurements made at the telescope. The map included most of Riccioli's and Schröter's names, 10 of Hevelius' and more than 140 new names added by Mädler. A consistent system for lettering subsidiary features was for­mulated: craters were assigned Roman letters; peaks and tines, Greek letters; for features the positions of which had been measured, capital letters were used; and unmeasured features were assigned lowercase letters. Furthermore, a letter was always placed on that side of a feature nearest the patronymic crater, a system that reduced obscuration by repetitious labeling.

In the latter half of the 19th century, astronomers in various countries drew detailed maps of the Moon, adding even more new names and re­placing letters with names. This development resulted in a very unsatis­factory state of affairs because some craters had as many as three different designations.

20TH CENTURY


In 1921, to clarify the existing situation and to standardize the nomen­clature, the newly formed International Astronomical Union ( IAU ) ap­pointed a small committee headed by Sir Frank Dyson, Astronomer Royal at that time. This work was completed in 1935 with the publication of Parts I and 11 of Named Lunar Formations by Blagg and Müller (ref. 1). (Often, the compilation is referred to as the "Blagg and Müller Catalog" or the "IAU Map.") This publication combined Mädler's nomenclature with those of all subsequent authors insofar as feasible; however, capital letters were used for subsidiary formations, irrespective of whether the positions had been measured. The authors assigned letters to many of the very small craters and hills (the positions of which Franz and Saunder had measured), with the peculiar result that the largest and smallest craters had designations, but many intermediate-size craters were unnamed.

Because use of the 1935 IAU publication revealed numerous incon­sistencies, an early task of the recently established (1960) Lunar and Planetary Laboratory (LPL) of the University of Arizona was a thorough revision and extension of both the map and catalog. The work was com­pleted in 1966. The new map and catalog, published by quadrants ( refs. 2 to 5), used a new nomenclature system that the IAU accepted in 1964 and 1967 to supersede the 1935 IAU system. Although the catalog listed only craters, the map designated rilles, peaks, promontories, and other lunar features. The LPL map and catalog were compiled using the best earth­-based lunar photography then available. In 1969, revised maps of the quadrants were issued (refs. 6 to 9).

Since 1966, study of the high-resolution Orbiter IV photographs has shown that many features that had been designated as craters are unworthy of such designation, usually because the features are merely irregular depressions. Such doubtful identifications have been omitted in this atlas, which contains the best of the Orbiter IV photography (highly oblique photographs and marginal-quality photographs have not been used).

Work on the Orbiter IV atlas and gazetteer was begun in June 1968 and continued intermittently through March 1970. Although the document initially was intended to assist Mapping Sciences Laboratory personnel at the Manned Spacecraft Center in rapidly locating named near-side lunar features, it soon became apparent that the potential worth of this atlas and gazetteer was great enough to warrant formal publication for wider dissemination. Relatively early in the project of compiling, verifying, and cross-indexing the comprehensive data gathered from numerous sources, the compilers decided that the high-resolution Orbiter IV photography would be superior to maps for presenting the information in clear, precise fashion. During the compilation, discrepancies in spelling, identification, and nomenclature were noted among the source documents; a significant amount of time and labor has been expended in resolving such discrepancies for this document.

The atlas and gazetteer comprises a systematic photographic and tabular catalog of officially named features of the lunar near side. Unofficial names not sanctioned by the IAU are not included, nor are far-side features for which adequate systematic photographic coverage is unavailable. This docu­ment should prove useful as a reference source not only to selenographers and serious investigators of lunar sciences, but also to students and scientists with only casual interest in lunar-surface features.