Hi Steve and Dennis,
I managed to make some long exposure shots with my DMK 21AF04.AS and the DMK's are really quite noise free. If they are at 60 mins I do not know. Following a few examples of longexpsoure shots
Stack of 30 images @ 9.709 seconds exposure time of the Egg Nebula, a planetary nebula
http://www.rainerehlert.com/DMK/Huevo-PK80-6.jpg
Please igonre the stars in form of a Diamond. I make my tests from my Studio and I can not get rid of the window
http://www.rainerehlert.com/astro/TOA130-SP03.jpg
StarTrek warship 001
Here the Blue Snowball nebula. A stack of 20 images @ 9.709 seconds
http://www.rainerehlert.com/DMK/PelotaNieve-Azul.jpg
and here a 55 second expsoure of the Saturn Nebula
http://www.rainerehlert.com/DMK/SaturnNebula.jpg
This a single frame in JPG @ approx 55 seconds and here the analysis of the noise
http://www.rainerehlert.com/DMK/DMK-Noise-01.jpg
as you see the Std. deviation is only 1.98 measured in the dashed box.
I think the DMK cameras are very promising. I ordered 2 more in color being the DBK 21AF04.AS and a DBK 41AF04.AS. I do not have the time in order to use a Filter wheel for LRGB and spent 4x as long as with a one shot color camera
PD There is a Yahoo group for discussing the DMK CCD cameras and can be found here
http://tech.groups.yahoo.com/group/DMKCCD-cameras/