Stacking Star Trails

For some of you this might be an old topic, but I just discovered this a few days ago.  I've run into it by accident while searching for something else.  It details a different way of taking a photo of star trails.  Basically instead of leaving the camera's shutter open for a long time, like 40 min or longer, one takes multiple photos of 4 to 5 minutes exposure time.  The whole reason for this is that with digital sensors opening a shutter for long periods of time will introduce digital noise in the picture.  Keeping the exposures shorter minimizes that noise. I was very eager to try this, and last night was a perfect clear evening.  So I setup my tripod on the deck and started snapping away.  Of course a remote cord is handy so you don't have to touch the camera, and keep it still.  I took 19 images of 4min each at 100 ISO and f5.6.  Then taken the images into Adobe Photoshop and each image at a separate layer.  This is what I got.

Star Trails

Next task is to find a better location.