Microchip has announced the latest in its line of miniature atomic clocks, offering wider temperature opertion and a 1Hz output. MAC-SA5X is a rubidium atomic with: <5.0E-11 frequency stability over operating temperature <5.0E-11 per month aging rate -40 to +75°C operation “Its combination of low monthly drift rate, short-term stability and stability during temperature changes ...

This story continues at Rubidium atomic clock in 2inch OCXO package

Or just read more coverage at Electronics Weekly