![The Optical Depth of [CII]: the Implications for Galaxies both Near and Far](https://www.sofia.usra.edu/sites/default/files/banner/guevara.png "The Optical Depth of [CII]: the Implications for Galaxies both Near and Far")
SOFIA Science Center
Stratospheric Observatory for Infrared Astronomy
SOFIA is an 80/20 partnership of NASA and the German Aerospace Center (DLR), consisting of an extensively modified Boeing 747SP aircraft carrying a 2.7-meter (106 inch) reflecting telescope (with an effective diameter of 2.5 meters or 100 inches). The aircraft is based at NASA's Armstrong Flight Research Center in Palmdale, Calif. The SOFIA Program Office is at NASA Ames Research Center in Moffett Field, Calif., which manages SOFIA's science and mission operations in cooperation with the Universities Space Research Association (USRA; Columbia, Md.) and the German SOFIA Institute (DSI; University of Stuttgart).
![Average spectra of the [CII] emission for M17 SW superposed on a composite image](https://www.sofia.usra.edu/sites/default/files/styles/homepage_queue/public/Public/SOFIA_Spitzer_M17_inset.png?itok=jnTAgspd "Average spectra of the [CII] emission for M17 SW superposed on a composite image")
