We describe the upgraded Polarimeter using Imaging CMOS Sensor and Rotating Retarder 2 (PICSARR-2), describe its applications, and characterize its performance for stellar polarimetry on a 36-inch and 14-inch telescope. On the larger telescope in the SDSS g′, r′ and i′ filters a precision of
Nearby in the stack
σp=
5.7 ppm on bright stars is recorded using a fast modulation rate corresponding to frame exposures of 12 ms; accounting for the internal errors in the individual observations gives a limiting precision of
ep=
1.3 ppm. Longer frame rates are required for stars with
m>5
, but the recorded errors only underperform a photon shot noise derived extrapolation for
m>8
, when even longer frame exposures are required. Stars as faint as
m=11
were observed. The position angle precision is measured as 0.0845 degrees, and there is very good agreement between observations made by both the PICSARR-2 and HIPPI-2 polarimeters. On the smaller telescope the instrument's performance approaches similar levels, and there is good cross-platform stability in the observation of standard stars. PICSARR-2 is therefore an excellent instrument to explore stellar variability due to a range of phenomena; examples from our ongoing pulsating star campaign and other variable star programs are presented.
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