We present infrared observations of the supernova remnant G21.5-0.9 with the Very Large Telescope , the Canada-France-Hawaii Telescope and the Spitzer Space Telescope .
Using the VLT/ISAAC camera equipped with a narrow-band [ Fe II ] 1.64 \mu m filter the entire pulsar wind nebula in SNR G21.5-0.9 was imaged .
This led to detection of iron line-emitting material in the shape of a broken ring-like structure following the nebula ’ s edge .
The detected emission is limb-brightened .
We also detect the compact nebula surrounding PSR J1833-1034 , both through imaging with the CFHT/AOB-KIR instrument ( K ^ { \prime } band ) and the IRAC camera ( all bands ) and also through polarimetric observations performed with VLT/ISAAC ( Ks band ) .
The emission from the compact nebula is highly polarised with an average value of the linear polarisation fraction P _ { \mathrm { L } } ^ { avg } \simeq 0.47 , and the swing of the electric vector across the nebula can be observed .
The infrared spectrum of the compact nebula can be described as a power law of index \alpha _ { IR } = 0.7 \pm 0.3 , and suggests that the spectrum flattens between the infrared and X-ray bands .