we've all seen many versions of the mid 1990s Light Pollution of the Night Sky maps from the data produced by an Italian university group.... some folks thought the Continental US data was flawed, and adjusted some of the parameters, and used circa 2001 satellite telemetry, along with census data and other inputs to the original light model. One of the reasons for doing this was that the original data set used winter telemetry from the Northeast US, and they assumed the snow cover would reflect more ligth into the sky.
Saturday, June 2, the Santa Cruz Astronomy Club setup at Henry Cowell State Park in support of their Full Moon Madness event.
We had 4-5 telescopes and a couple pairs of nice binoculars on parallelogram mounts. I got their early, as there was a good number of sunspots, and setup the Celestron 80mm Superpolaris for solar. Before long Bill showed up and setup his green dob on the eq platform for exactly the same thing.
At tonight's regular Bonny Doon star party, I was tired, so I only shot one series of 20 1min exposures of m13 with my DSLR through the celestron/vixen 80mm super-polaris.... half were sketchy (elongated stars at a pixel level), so I know I definitely need to come up with an autoguider. but the other 10 were good enough, albeit somewhat underexposed, that I was able to stack this, with a bit of contrast curve adjustments (black stayed black, white stayed white, I just steepened the curve a lot at the dark end)