Ozone monitoring instrument
The ozone monitoring instrument (OMI) is a nadir-viewing visual and ultraviolet spectrometer aboard the NASA Aura spacecraft, which is part of the satellite constellation A-Train. In this group of satellites Aura flies in formation about 15 minutes behind Aqua satellite, both of which orbit the Earth in a polar Sun-synchronous pattern, and which provides nearly global coverage in one day.
Source: Wikipedia — Ozone monitoring instrument (CC BY-SA 4.0)