There are some celestial bodies that use planetographic coordinates (http://planetarynames.wr.usgs.gov/TargetCoordinates), increasing to the West, and currently Wikidata does not support this system.

Example: http://en.wikipedia.org/wiki/Adlinda_(crater)

It has coordinates (source: http://planetarynames.wr.usgs.gov/Feature/54):

• 48.5 South
• 35.6 West

Now in Wikidata coordinates are (http://www.wikidata.org/wiki/Q2577126):

• -48.5
• 35.6
• globe: callisto

However, the web interface shows:

• 48°30'0.000"S, 35°36'0.000"E (East instead of West)

because Wikidata does not manage planetographic coordinates.

Sometimes instead in Wikidata celestial bodies with planetographic coordinates (according to the source) use planetocentric coordinates, example: https://en.wikipedia.org/wiki/Asgard_%28crater%29 => 32.2° North, 139.9° West according the source: http://planetarynames.wr.usgs.gov/Feature/420 => but 32.2, -139.9° in Wikidata (https://www.wikidata.org/wiki/Q724438).

In this way there is a great confusion among Wikidata items, and among Wikidata and the source. Coordinates are inusable for celestial bodies different from the Earth.

It is therefore necessary:

• the web interface should allow you to specify the coordinate system (planetocentric or planetographic)
• or if this is not possible, it should be clarified which is the one and only coordinate system for all celestial bodies.