  In this study we revisit public data on the supersoft X-ray source CAL 83 in
the Large Magellanic Cloud. A significant part of our analysis is focused on
XMM-Newton X-ray observations, in which updated data reduction procedures and
quality assessment were applied. We report on the capability of publicly
available hot atmosphere models in describing the source's soft X-ray spectrum.
By gathering historical flux measurements in multiple wavelengths and comparing
them with the fluxes derived from the X-ray analysis, we find that a $\sim$ 360
kK phenomenological blackbody model describes the spectral energy distribution
of CAL 83 fairly well. We also retrieve data from the XMM-Newton UV/optical
camera, which is co-alligned with the X-ray instruments and provides strictly
simultaneous measurements. These observations demonstrate that the X-ray
emission is definitely anti-correlated with emission at longer wavelengths in a
time-scale of days to weeks. A closer look at simultaneous X-ray and UV count
rates in single light curves reveals that the anti-correlated behaviour is
actually present in time scales as short as minutes, suggesting that the origin
of variable emission in the system is not unique.
