For years the US Naval Observatory would generate a precise .gif of the master time clock. Alas it seems the service has been discontinued, unless someone here can find the new home for the .gif generator. This is the dead link:

http://tycho.usno.navy.mil/cgi-bin/nph-usnoclock.gif?zone=es...

The last message from Tycho about the gif clocks: https://web.archive.org/web/20191015032841/http://tycho.usno...

The Precise Time Department is here now:

https://www.cnmoc.usff.navy.mil/Our-Commands/United-States-N...

They now refer Time Displays to https://www.time.gov