You are correct and i believe its about thirty minutes -see below
_setSessionTimeout()
_setSessionTimeout(newTimeout)
This method is deprecated. Please use [_setSessionCookieTimeout](http://code.google.com/apis/analytics/docs/gaJS/gaJSApiBasicConfiguration.html#_gat.GA_Tracker_._setSessionCookieTimeout)(cookieTimeoutMillis)
instead.
Sets the new session timeout in seconds. By default, session timeout is set to 30 minutes (1800 seconds). Session timeout is used to compute visits (see Session in our Help Center). If you want to change the definition of a "session" for your particular needs, you can pass in the number of seconds to define a new value. This will impact the Visits reports in every section where the number of visits are calculated, and where visits are used in computing other values. For example, the number of visits will generally increase if you shorten the session timeout, and will generally decrease if you increase the session timeout.
parameters