Thanks for the inputs. Due to the length of the artifacts, I don't believe they are due to the earth's rotation. I varied the exposure times between about 10 and 20 s. Maybe long enough for very short tracks, but I'm pretty sure it's due to camera movement. I'm going to get out one night soon and do some testing. I will report back.You also have add in the crop factor for the sensor size of the camera. The example above uses a full frame camera. Those cameras have a crop factor of 1 to 1. Your Osmo uses a 1/2.3 sensor that has a crop factor of 1/5.62. So if your Osmo has a 20mm lens you are going to be around a 5 second shutter length before seeing star trails. 20mm X 5.62=112.4 , 500 divided by 112.4=4.45 seconds.