近红外白天恒星探测对比度分析

红外波段可以探测到足够多的星体用以导航。恒星-背景对比度是白天恒星探测时的一个重要指标，分析近红外波段，6星等恒星对比度随太阳天顶角、探测器高度和探测方位角的变化情况。结果显示，恒星-背景对比度随太阳天顶角近似于指数增长，40太阳天顶角时对比度是20时的2.69倍左右；一定高度时，对比度随探测器高度的增加近似指数增加，低于15 km时对比度仍小于3， 80 km时对比度达到60左右；随着探测方位角的增大，恒星-背景对比度基本上线性增大，30探测方位角时的对比度是0探测方位角时对比度的2.38倍。

Near-infrared contrast of star to sky background during daytime

The infrared waveband can detect enough stars for navigation. The contrast of star to sky background is an important parameter of star detection during daytime. This paper analyzed the 6 magnitude star contrast changing with the solar zenith angle, detector height and detection azimuth in near-infrared band. Results show that the star to sky background contrast performs approximate exponential growth with the solar zenith angle, and the contrast with 40°solar zenith angle is about 2.69 times of 20°;above a certain height, the contrast performs approximate exponential growth with the increase of detector height, it is lower than 3 when the height is less than 15km, but increasing quickly to 60 at 80km; the star to sky background contrast nearly increases linearly with the increase of detection azimuth, and the contrast with 30°azimuth is 2.38 times of 0°.