We present UV/optical photometric and spectroscopic observations of PS16aqv ( SN 2016ard ) , a Type I superluminous supernova ( SLSN-I ) classified as part of our search for low- z SLSNe .
PS16aqv is most similar in timescale and spectroscopic evolution to fast evolving SLSNe-I and reached a peak absolute magnitude of M _ { r } \approx - 22.1 .
The lightcurves exhibit a significant undulation at 30 rest-frame days after peak , with a behavior similar to undulations seen in the slowly fading SLSN-I SN 2015bn .
This similarity strengthens the case that fast and slow SLSNe-I form a continuum with a common origin .
At \approx 80 days after peak , the lightcurves exhibit a transition to a slow decline , followed by significant subsequent steepening , indicative of a plateau phase or a second significant undulation .
Deep limits at \approx 280 days after peak imply a tight constraint on the nickel mass , M _ { Ni } \lesssim 0.35 M _ { \odot } ( lower than for previous SLSNe-I ) , and indicate that some SLSNe-I do not produce significantly more nickel than normal Type Ic SNe .
Using MOSFiT , we model the lightcurve with a magnetar central engine model and find P _ { spin } \approx 0.9 ms , B \approx 1.5 \times 10 ^ { 14 } G , and M _ { ej } \approx 16 M _ { \odot } .
The implied rapid spin-down time and large reservoir of available energy coupled with the high ejecta mass may account for the fast evolving lightcurve and slow spectroscopic evolution .
We also study the location of PS16aqv within its host galaxy and find that it occurred at an offset of 2.46 \pm 0.21 kpc from the central , most active star-forming region .
We find the host galaxy exhibits low metallicity and spatially varying extinction and star formation rate , with the explosion site of PS16aqv exhibiting lower values than the central region .
The complexity seen in the lightcurves of PS16aqv and other events highlights the importance of obtaining well-sampled lightcurves for exploring deviations from a uniform decline .