Is there a way to export in a single CSV file the instrumental magnitudes of all target, comparison and check stars from each image of a time series? Cheers,
You can export some of that info in Time Series - General Export, but not all. You can get IM of the target over time, and the reduced mags of the target and check over time in one text file.
You can get all that info for target, comps and check in a single image photometry page download.