double rainbows (Blue Mountains)

I spotted a rainbow out the kitchen window. It grew brighter as we gathered on the back step. Then brighter still. A rather bright secondary rainbow appeared. It was impressive. When I returned with my camera and wide angle lens, it was fading.

Canon 40D, Rokinon 8mm, 1/500, ISO 800, aperture unknown, RAW, manually focused, Digital Photo Professional 4.6.10.0.