Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808

We present Dark Energy Camera imaging for the peculiar Galactic globular clustersNGC 1851, NGC1904 (M 79),NGC2298 andNGC2808. Our deep photometry reveals that all the clusters have an important contribution of stars beyond their King tidal radii and present tails with different morphologies. We have also explored the surroundings of the clusters where the presence of the Canis Major overdensity and/or the low Galactic latitude Monoceros ring at d_⊙ ~ 8 kpc is evident. A second stellar system is found at d_⊙ ~ 17 kpc and spans at least 18 deg × 15 deg in the sky. As one of the possible scenarios to explain that feature, we propose that the unveiled system is part ofMonoceros explained as a density wave moving towards the outer MilkyWay. Alternatively, the unveiled system might be connected with other known halo substructures or associated with the progenitor dwarf galaxy of NGC1851 and NGC1904, which are widely considered accreted globular clusters.