light pollution

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Robin Leadbeater

Hi Paul,

Here’s mine with the ALPY 200 from my reasonably dark rural site, from this poster paper

The comparison with the VLT was interesting. (note the high natural pollution from OH band emission in the IR) 

It has certainly become worse over the years in quantity and complexity though with a shift locally from LP sodium to a mix of HP sodium, metal halide and now  LED, particularly the ones high in blue.  Sky background subtraction does indeed work very well eg  as here where  the signal is much lower than the sky background (It still adds noise though and I think is ultimately limiting my sensitivity)