Hi Robin,
I expect that observing a very red star made a big difference in how faint I could go. I could not find any R magitude measurements but I’m sure it would have been brighter than 13th mag through an R filter.
There is also of course a difference between obtaining a high quality spectrum, and simply looking for a detection of whether or not H-alpha is in emission. My next challenge will be to learn to flux calibrate my spectra, so I can properly analyse the intensity changes for a future cycle of chi Cyg.
Best wishes,
Andy