It is by far the darkest sky I have ever seen at Henry Coe. The marine layer was already visible from south over Gilroy at sunset, and it covered sky glow from Gilroy and Morgan Hill around midnight. By ~2AM sky glow from Silicon Valley was also completely blocked by marine layer.
Unfortunately when I examined my subs of Western Veil Nebula, I noticed that it was slightly out of focus, especially those taken after mid night. I think the problem was that I focused the telescope at 9PM when the ambient temperature was still relatively mild and did not re-focus when temperature dropped. One more lesson learned.
Location: Henry Coe State Park, Morgan Hill, CA
Condition: excellent transparency, excellent seeing
Imaging: AT111 EDT/AT2FF/CGEM/STF8300C
Guiding: AT72ED/Orion SSAG/PHD
Exposure: 12 x 15′ subs, dark/bias/flat calibrated