557.7nm optical bandpass filter for thermospheric dynamics studies...
The 557.7nm filter is an oxygen emission line. One really exciting use is for Aurora detection (like the Borealis). It is also used in Over-the-Horizon Radar systems measuring airglow (light resulting from chemical reactions in the atmosphere) The 557.7nm is used in conjunction with 572.4nm, 589.3nm, 630nm and 777.4nm. Each wavelength is good for a certain altitude with the 572.4nm being the control.
