Further information as an aid to diagnosis.

I ran INDI/Ekos with the telescope simulator and the ccd simulator. The ccd simulator has a field of view 133' by 107'. After picking an arbitrary point on the star map (RA 12:26:31 DE 69:41:47)and starting tracking I invoked "Capture & Solve" under the Ekos align tab. This produced an error message saying "index files index-4205 to index-4211 are missing" and the solver failed to work. When I used the ccd simulator (so same field of view)to take an image of the sky and then invoked "Load & Slew" under the Ekos align tab the solver worked fine and slewed the telescope to the appropriate co-ords. When I used "Load & Slew" with an image of the region around M31 I had taken some time ago the solver also worked and the simulated telescope slewed to M31 on the star map. My image was taken with a QHY5Lii on a 130mm focal length telescope and thus had a field of view 128' by 96' - almost the same as the ccd simulator and requiring the same astrometry files for solving.

The problem, therefore, appears to be with the "Capture and Solve" procedure rather than with the use of the astrometry files generally.

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