  We observed the slowly revolving pulsar 1E 161348-5055 (1E 1613, spin period
of 6.67 h) in the supernova remnant RCW 103 twice with XMM-Newton and once with
the Very Large Telescope (VLT). The VLT observation was performed on 2016 June
30, about a week after the detection of a large outburst from 1E 1613. At the
position of 1E 1613, we found a near-infrared source with K_S = 20.68 +/- 0.12
mag that was not detected (K_S > 21.2 mag) in data collected with the same
instruments in 2006, during X-ray quiescence. Its position and behavior are
consistent with a counterpart in the literature that was discovered with the
Hubble Space Telescope in the following weeks in adjacent near-IR bands. The
XMM-Newton pointings were carried out on 2016 August 19 and on 2018 February
14. While the collected spectra are similar in shape between each other and to
what is observed in quiescence (a blackbody with kT~0.5 keV plus a second,
harder component, either another hotter blackbody with kT ~ 1.2 keV or a power
law with photon index ~3), the two pointings caught 1E 1613 at different
luminosity throughout its decay pattern: about 4.8E34 erg/s in 2016 and 1.2E34
erg/s in 2018 (0.5-10 keV, for the double-blackbody model and for 3.3 kpc),
which is still almost about ten times brighter than the quiescent level. The
pulse profile displayed dramatic changes, apparently evolving from the complex
multi-peak morphology observed in high-luminosity states to the more sinusoidal
form characteristic of latency. The inspection of the X-ray light curves
revealed two flares with unusual properties in the 2016 observation: they are
long (~1 ks to be compared with 0.1-1 s of typical magnetar bursts) and faint
(~1E34 erg/s, with respect to 1E38 erg/s or more in magnetars). Their spectra
are comparatively soft and resemble the hotter thermal component of the
persistent emission.
