Editted to add: Well, if everyone else is doing 4 am, I'm game for that. Everyone obviously will have a light with them (right?!? for late night safety options if nothing else). We will have red-eyed into PHX Thursday/Friday night but maybe 2/3 of us can snooze on the drive up Friday.
From the site, http://www.sunrisesunset.com/USA/NationalParks/
for GCNP South Rim, April 14th:
Civil Twi: 5:30am
Civil Twi: 7:27pm
A day past (less than) last quarter of the moon.
Civil twilight (sun is 6 degrees below horison) is pretty conservative for hiking, IME. Nautical twilight (12 degrees) is pretty darn hikeable and that gives a window from 5 am to 8 pm without the need for headlamps. There'll be a "half" moon low to the SE and most of SK faces N and W, so counting on moon light to start at 4 am seems a little dodgy to me. And there will be NO evening moonlight.
For us hiker-runners (with an emphasis on the hiking) which I believe includes Alaskans Tony and me and Mike from Montana, I'm thinking we want to maximize our daylight for a 14-15-16 hour day. It would be a pity to miss sunrise by starting after 6 am. I'm thinking wake up at 5 am, SK trailhead at 5:30 am.
You guys (and gal) who can do it in 10 hours could sleep in and get your beauty rest. We'll say "hi" as you blast past us.
I've got my high-altitude training scheduled way too soon (backpacking with the kids at 8,000 feet on Haleakala, leaving tomorrow), so I'll be mostly off-line for 8 days.