Hello Tracker users,

I've released a Tracker 5.1.1 upgrade that uses the secure https protocol instead of plain http whenever Tracker talks to its web server. While you will not see any changes as a user, this is an important upgrade because in about a week the physlets.org server that hosts Tracker will require the https protocol and earlier versions (including 5.1.0) will report a confusing message when they check for the latest version. Note that the confusing message will NOT prevent Tracker from operating correctly, but it will be an annoyance.

To upgrade, click the green "Now available" button on the toolbar and choose Upgrade Now. If you don't see the button choose Help|Check For Upgrades.

Full installers are also available for Windows, Mac and Linux from both the Tracker home page (http://physlets.org/tracker/) and ComPADRE (http://www.opensourcephysics.org/items/detail.cfm?ID=7365).

Thanks!  Doug