Your mount's tracking turned off after the third sub frame.
What was the Hour Angle of the mount when the fourth frame was taken? Was it at the Meridian Limit of your mount?
I.e., was the OTA pointed near to the Meridian when you started the run?
German mounts will, by themselves, stop tracking when they reach the Meridian Limit (a parameter that can be entered in the hand controller).
You will need to send the mount a GOTO command once the target has reached the other side of the Meridian. The mount will then execute a Meridian Flip.
This is to keep the OTA and other instrumentation (eyepieces, cameras, etc) from eventually crashing into the tripod.
You can also ask the computer to automatically flip at the appropriate time -- but with the ASIAIR, that can be unreliable, since it often has no idea when the appropriate time is due to ZWO's poor understanding of the Local Sideral Time; and that might have been what happened to you, in spite of turning "Auto Meridian Flip" on.
Chen
