Lunar exosphere influence on lunar-based near-ultraviolet astronomical observations |
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Authors: | J Wang JS Deng J Cui L Cao YL Qiu JY Wei |
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Institution: | National Astronomical Observatories, Chinese Academy of Sciences, 20A, Datun Road, Chaoyang District, Beijing 100012, China |
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Abstract: | The potential effect of the lunar exosphere on the near-ultraviolet sky background emission is predicted for Lunar-based Ultraviolet Telescope (LUT: a funded Chinese scientific payload for the Chang’e-III mission). Using the upper limit on the OH concentration inferred from the recent MIP CHACE results, our calculations show that the sky brightness due to the illuminated exosphere is <8.7 photons−1 cm−2 arcsec−2 within the wavelength range 245–340 nm. By evaluating the signal-to-noise ratios of observations of an AB = 13 mag point source at a series of sky background levels, our analysis indicates that the detection performance of LUT can be moderately degraded by the lunar exosphere emission in most cases. An AB = 13 mag point source can still be detected by the telescope at a signal-to-noise ratio more than 8 when the OH concentration is less than 2 × 108 molecules cm−3. However, the effect on the performance is considerable when the exosphere is as dense as suggested by CHACE. |
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Keywords: | Lunar exosphere Sky background Rayleigh scattering Resonance fluorescence Emissive photodissociation Lunar-based Ultraviolet Telescope |
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