Why are there no matched stars - markmac99/ukmon-pitools GitHub Wiki

There are a few reasons why you might have no matched stars.

• It might have been too cloudy. RMS needs at least 20 stars so if there are insufficient stars visible then you'll see this message.
• Your camera's focus might have drifted too much and RMS can't identify the out-of-focus stars. You don't want pinpoint focus, but it should be pretty close.
• Finally if you've had a clear night and focus is good but RMS still couldn't match stars, then your camera has moved out of position. This can be caused by wind, loose bolts, birds perching on the camera, or even thermal effects (the camera cases heat up and cool down a lot each day).

To recalibrate the camera follow the advice here . This will remap the camera's view to the starfield, creating a file called a platepar.