Can't get release dates for Boost versions older than 1.53.0 from GitHub

TL;DR: Where should we get the release date for Boost releases prior to 1.53.0? cc @4down

I was getting it from the GitHub tag, but in doing some other work, I realized that the GitHub tag dates basically stop in 2013 (example: https://github.com/boostorg/boost/tags?after=boost-1.46.1 — scroll before or after this tag and you see April 13, 2013 a lot).

Example: Boost 1.43.0: https://github.com/boostorg/boost/releases/tag/boost-1.43.0 — says April 13, 2013
On Boost: https://www.boost.org/users/history/version_1_43_0.html — says May 6, 2010

There are also small date discrepancies with more recent versions. Example Boost 1.82.0:
On GitHub: https://www.boost.org/users/history/version_1_82_0.html shows April 13
On Boost: https://www.boost.org/users/history/version_1_82_0.html shows pril 14

I’m betting 2013 was when Boost joined GitHub, but that means that prior to appx. version 1.53.0, the date associated with the tag is not actually the release date. So what is the source of truth for this data?