This timeline of Gundam's Universal Century is, of course, a work in progress. For the time being it extends only up through the end of the One Year War, with the events of later stories to be added in stages. It's based on the timelines published in MediaWorks's Data Collection books, which are in turn updated versions of those in Bandai's Entertainment Bible series. The Data Collection timeline appears to be the current official standard, and is reproduced in official Sunrise publications such as event programs and museum catalogs.
I've also added events from several other publications, including books, magazines, model kit manuals, DVD liner notes, and the Zeon Military File CD-ROM. I've listed the source of each addition, in some cases noting conflicting accounts and explaining why I chose the ones I did. Note that Kodansha's Sunrise-approved Gundam Officials encylopedia is mostly a compilation of previously published information, so I've credited it only when it corrects or adds to these primary sources.