Designing considerations for airborne star tracker during daytime

This paper aims at determining several designing considerations for star tracker which uses on aircraft during daytime at altitudes around 10 km. From analysis of operational environment, the sky background radiation caused by the sun is the main factor which affects the performance of star tracker. In order to research insight, star magnitude model is established to calculate stellar radiation and MODTRAN software is used to obtain the sky background radiation. The contrast of detection, the ratio of stellar radiation and sky background radiation, is defined as the criterion to determine these considerations. Finally, H-band waveband, from 1.5μm to 1.7μm, is chose as the optimal detection waveband due to better comprehensive performance in detection. InGaAs detector is selected for the airborne star tracker after trade-off studies included a comparison in terms of detector format, cost and cooling requirements. Simultaneous measurements with three field of view are determined as the preferred design prototype because of higher detectable limiting magnitude and star detection probability.