  In 2014 the number of active cell phones worldwide for the first time
surpassed the number of humans. Cell phone camera quality and onboard
processing power (both CPU and GPU) continue to improve rapidly. In addition to
their primary purpose of detecting photons, camera image sensors on cell phones
and other ubiquitous devices such as tablets, laptops and digital cameras can
detect ionizing radiation produced by cosmic rays and radioactive decays. While
cosmic rays have long been understood and characterized as a nuisance in
astronomical cameras, they can also be identified as a signal in idle camera
image sensors. We present the Distributed Electronic Cosmic-ray Observatory
(DECO), a platform for outreach and education as well as for citizen science.
Consisting of an app and associated database and web site, DECO harnesses the
power of distributed camera image sensors for cosmic-ray detection.
