Towards a Daytime and Low-altitude Stellar Positioning System: Challenges and First Results

Since the emergence of electronic image sensors, stellar pictures can be easily processed by computers to identify stars and measure angles: distance between light spots on same scene or angle above visible horizon, like sextant does for celestial navigation. Adding an inclinometer camera axis, computer is now able calculate attitude angles (course, trim list) in a local coordinate system position (latitude, longitude even altitude). The last coordinate, time, may measured observing angular distances sphere located near orbit satellite (Moon LEO). If sensor vehicle, gyroscopes are necessary smooth rotations vibrations. Going from this appealing theory reality daytime positioning hides many challenges such as detecting day, at low altitude bad weather. level accuracy increases, sources error emerge, e.g., sky background, diffraction limit, vertical deflection. Many prototypes manufactured products have shown potential thanks maturity technologies inertial sensors silicon CMOS detectors. Most these applications designed operations as: • yield satellites, stratospheric balloons, high aircraft missiles; adjust civil aircraft; parameters immobile ground telescopes altitude; but rarely positioning. challenge lies tracking moving vehicle during altitude: sea land. lower layers atmosphere add numerous perturbations, forcing work day infrared band, where sensitivity ends InGaAs starts (or other technologies). This paper aims looking compromise detector technologies, detectability, duration availability results sea. A first parameter transmission atmosphere: when wavelength scattering decreases thermal emissions submerge starlight. Some bands obscure it transmit photons molecular resonance fluorescence sunlight. rigorous simulation radiative transfer with weather figure out best band transmission. Secondly, number observable each given magnitude flux, increases wavelength… except R (0.6-0.7?m) I (0.7-1.0?m) we few data star catalogs: magnitudes been calculated comparing their known spectral type, confirming tendency. Lastly, technology detection well developed public cameras smartphones: size pixels allow measurements. In opposite, Short Wave InfraRed detectors (SWIR: 1.0–2.5 ?m) suffer bigger pitch poor definition. But SWIR remains high, performances improving quickly. Betting ascending readiness, tests realized: simulations confirmed, new occur. Table contents. 1 – Observation tool 2 through 3 Detectable 4 Single multi observation 5 Tests 8 6 Accurate horizon?