I observed the Comet C/2017O1 ASSSN yesterday (28.09.17). I used prism to control all equipment (like CCD/Mount/filter wheel/focuser). The mount gone right to the target (comet C/2017O1) after plate solve using UCAC4 catalog provided by you.
I stacked comet image using prism (FITS files are not dark/flat/bias calibrated as I have to generate new files for this setup). prism did the stacking job nicely, the stacked image is attached below.