Abstract:
Software simulators are now widely used in all areas of science, especially in application to astronomical
missions: from instrument design to mission planning, and to data interpretation. We present a simulator
to model the diffuse ultraviolet sky, where the different contributors are separately calculated and added
together to produce a sky image of the size specified by the instrument requirements. Each of the
contributors to the background, instrumental dark current, airglow, zodiacal light and diffuse Galactic
light, depends on different factors. Airglow is dependent on the time of day; zodiacal light depends on
the time of year, angle from the Sun and from the ecliptic; diffuse UV emission depends on the line
of sight. To provide a full description of the sky along any line of sight, we have also added stars. The
UV background light can dominate in many areas of the sky and severely limit viewing directions due
to overbrightness. The simulator, available as a downloadable package and as a web-based tool, can be
applied to preparation of real space missions and instruments. For demonstration,wepresent the example
use for the two near-future UV missions: UVIT instrument on the Indian Astrosat mission and a new
proposed wide-field (∼1000 square degrees) transient explorer satellite.
