GLUV: a balloon-borne high-cadence ultraviolet monitoring telescope for supernova shock breakouts and exoplanet atmospheres

Routine photometric monitoring at near-ultraviolet wavelengths (< 400 nm) is compromised from the ground due to highly variable atmospheric transmission and cloud cover. The GLUV project will mount a modest sized telescope (200 mm primary) on a series of long-duration high-altitude balloon flights. The wide field camera (~7 deg2) will perform high cadence (10-300 second rolling integrations) each night for campaign durations of three to six months. The principle science mission is the early-time detection of supernova shock-breakout at near-ultraviolet wavelengths. Additionally, early design analysis has shown the system is also able to probe the atmospheric composition of exoplanet atmospheres through the combination of UV transit measurements with ground-based measurements at longer wavelengths. In this presentation we consider the specifications for a long-duration balloon platform for such a mission, focusing on the necessary mission requirements (sensitivity, sky coverage, cadence etc.) and the available platform suitability. Particular attention is paid to platform flight altitude and atmospheric transmission.