Paul Leyland

contains two, one at 143 and the other at 153.  Both are inconveniently distant at around 15-20 arcmin (a guess from the chart scale – I have not measured them).

Personally I´d use them to measure the instantaneous brightness of other stars closer to the SN and then measure the SN with respect to them.  If the images of the fields are taken within a few minutes of each other, it is very unlikely indeed that all the secondary comparisons are variable on that timescale, and not very likely that even one will be. If one or more is a LPV, who cares? It’s constant for all practical purposes.

If you discover that one or more field stars varies from night to night, that in itself is worth reporting.