Expired Glympses remain visible for 48 hours before they are permanently deleted.
Expired Glympses are visible for a short period of time for two reasons. First, as a convenience for users who are trying to meet up. This saves the sender from having to send a new Glympse when a friend may just need an extra few minutes to navigate to their location.
Second, for users who like to post a Glympse of their location to their Facebook timeline. Since people tend to check Facebook periodically and sometimes just once or twice a day, this allows a sender to share their trail with friends and know that they won't just see a blank map because the Glympse expired earlier that day.
Users who want their Glympse to disappear immediately (before the automatic 48 hour period) can delete the Glympse in the Recents screen of the app. Once deleted in the app, a Glympse will immediately be non-visible to anyone.