[snopercod]

Lots of eyewitness reports on this thread: Columbia Reentry Observations.

This site allows you to calculate the time of sunrise for a given day and location. You'll have do do a litle trig to factor in the altitude.

Carbon is a conductor. I don't know about RCC.

[RandyRep]

Great site for SR SS times. When I was doing radio wave propagation in an earlier life, I had a BASIC program to do it for any location and altitude.

From the site:

San Francisco: civil twilight starts at 0647 PST on 1 Feb, sunrise is at 0714 PST

Flagstaff: civil twilight starts at 0600 PST on 1 Feb, sunrise is at 0626 PST

I corrected the Flagstaff times to PST. So, when the orbiter passes over San Francisco, it was well before civil twilight on the ground. When it breaks up over New Mexico and western Texas, it was just civil twilight at Flagstaff on the ground.

I simplified the trig to assume that the sun's latitude was inconsequential...assuming that the orbiter was at a 40 mile altitude, and an earth radius of 3960 miles, the arc length on the earth's surface is 8.1 degrees or 560 miles. This results in solar illumination at 40 miles altitude of about 32 minutes before ground sunrise.

Based on that, the orbiter was not illuminated yet over San Francisco (sunrise at 40 miles altitude at 0642 PST), but was illuminated over Flagstaff (sunrise at 40 miles altitude about 0554 PST). For a 60 mile altitude (9.9 degrees arc length), you could subtract another 8 minutes or so.