I think this would be more useful if the color bar had a slider that tracked the user's mouse across the map. Also, where does the color bar information come f

I think this would be more useful if the color bar had a slider that tracked the user's mouse across the map. Also, where does the color bar information come from? Is it from observational data of the dimmest magnitude stars or objects visible at a particular location or is it just integrating data from satellite based night-time passes to show light received on clear-sky passes? Seems to be moderately useful but the actual utility of anything like this is dependent on the source and processing of the data used to create it.