In 2010, the coordinates of the named features in the lunar portion of the nomenclature database were updated from values from historical sources to values in the coordinate frame of the Unified Lunar Control Network 2005 (ULCN 2005, see http://pubs.usgs.gov/of/2006/1367/). The purpose of this work was to facilitate the identification of named lunar features. Dots representing the coordinates of the centers of named features will fall in the centers of the features when displayed on any map product that was created using the same ULCN 2005 control network.
The extents and sizes of the named features were also updated; these data are approximate and are intended solely to give the user sufficient information to identify named features and their rough extents. A link to a more precise crater database (now in preparation) by Dr. Nadine Barlow will be provided when available.
This new set of coordinates was derived using ArcMap version 9.3.1 and the Lunar Orbiter Digital Photographic Mosaic (http://www.mapaplanet.org/explorer/help/data_set.html#moon_lo). Where data gaps exist in the Lunar Orbiter image, the features were aligned with the USGS airbrushed shaded relief mosaic, which was warped to the same control network as the Lunar Orbiter mosaic (ULCN 2005) (see http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2245.pdf).
The lunar portion of the Gazetteer of Planetary Nomenclature web site now defaults to showing feature coordinates in the frame of the ULCN 2005 control network. The original ‘unknown’ source coordinates are still retained in the gazetteer, but this data set is now considered archival and will not be updated with new names or changes to approved names.