What are the differences two databases in the Title? So far I've dragged up this, but perhaps there's more detail elsewhere? Some people are apt to wonder why this database is used instead of the Lowell Observatory ASTORB dataset. mpcorb has several advantages over ASTORB. mpcorb contains currently visible objects; ASTORB contains a lot of objects that were observed briefly, long ago, and which are essentially "lost" now. mpcorb tends to be slightly more up to date (understandable, since ASTORB is based on waiting for MPC data to arrive). At some point, I may revise Guide to work with either dataset. But it does appear that mpcorb is best suited to the use of observers; this was my primary goal. in <http://www.projectpluto.com/mpcorb.htm#in_guide>. There's talk of Guide and Charon there. I'm guessing those are some sort of databases.