As a response to Bobs challenge (http://blogs.mathworks.com/pick/2008/06/27/atomic-clock-alarm-challenge/), I integrated the suggestion by JesseL to use the US Naval Observatory clock as a reference in the original remindme by Matt Fig. Accuracy is limited by lag in retrieving the time, and no corrections are done for clock drift from the alarm is set until it is triggered.
Daniel Armyr (2020). Atomic reminder (https://www.mathworks.com/matlabcentral/fileexchange/20693-atomic-reminder), MATLAB Central File Exchange. Retrieved .
This submission no longer works because the URL is invalid. All of the solutions I've come accross rely on broken URLs. This seems to be a serious limitation since the web developer could change the URL at any point. I'm still searching for a more robust solution.