  Light curves of the Z Cam type dwarf nova AT Cnc observed during standstill
in 2016 and 2018 are analyzed. On the time scale of hours, previous reports on
periodicities, in particular the presence of negative superhumps, could not be
confirmed. Instead, a modulation with a period equal to the spectroscopic
orbital period was detected which we thus interpret as a manifestations of the
binary revolution. It enables us to derive a more accurate value of 0.201634
$\pm$ 0.000005 days (or its alias of 0.021580 days) for the period. AT Cnc also
exhibits a hitherto unreported modulation of 25.731 $\pm$ 0.005 min, stable in
period but not in amplitude over the entire time base of two years of the
observations. We tentatively interpret this modulation in the context of an
intermediate polar model for the system.
