Under 14 CFR § 107.29(c), civil twilight (except in Alaska) is defined as —
Why: 14 CFR § 107.29(c) defines civil twilight (outside Alaska) as a period beginning 30 minutes before official sunrise and ending at official sunrise, and a period beginning at official sunset and ending 30 minutes after official sunset.
1 hour is not the figure in § 107.29(c); this overstates the 30-minute margin the rule actually specifies.
Nautical twilight is a longer, different astronomical definition than civil twilight; part 107's lighting rule is tied specifically to civil twilight's 30-minute windows, not nautical twilight.