Multiwavelength observations are crucial to understand the diversity in this class of supernovae. Radio studies provide diagnostics of the CSM. At the same time X-ray studies determine the shock temperature and also provide unique constraints on the ejecta structure. Thus radio and X-ray bands combined together constrain the past evolution of the progenitor star's mass loss in the stellar wind. Optical emission from these supernovae is likely to be from circumstellar interaction. An IR excess, which is probably due to thermal emission from hot dust, may reveal the extended CS dust surrounding SNe. Hence, understanding the SNe IIn phenomenon requires a complex observational study of their optical, infrared, X-ray and radio emission, and modeling of the emission characteristics in terms of physical models that include ejecta and CSM properties (density, extension, clumpiness, asymmetry).

We have carried out a campaign to understand these supernovae in radio and X-ray bands. So far, we have observed around 50 Type IIn supernovae with the VLA and detected only 4, which are SN 2005kd, SN 2006jd, SN 2008iy, SN 2009ip and SN 2010jl. We have studied suitable candidates with the Chandra, XMM-Newton telescopes and Swift-XRT in X-ray bands. The X-ray detected supernovae in these campaign are SN 2006jd, SN 2009ip and SN 2010jl. All these supernovae have provided us a wealth of observations. In SN 2006jd, the radio absorption have been explained by cool gas mixed in the forward shock. In SN 2010jl, we have wtinessed the evolution of the circumstellar column density for the first time. This is an ongoing campaign and more studies are underway.