We report on new 5-GHz VLA radio observations of the pulsar-powered supernova remnant G21.5 - 0.9 .
These observations have allowed us to make a high-quality radio image of this remnant with a resolution of \sim 0.7″ .
It has a filamentary structure similar to that seen in the Crab Nebula .
Radio structure suggestive of the torus seen around the Crab pulsar is tentatively identified .
We also compared the new image with one taken \sim 15 yr earlier at 1.5 GHz , both to find the expansion speed of the remnant and to make a spectral index image .
Between 1991 and 2006 , we find that the average expansion rate of the remnant is 0.11 \pm 0.02 % yr ^ { -1 } , corresponding , for a distance of 5 kpc , to a speed of 910 \pm 160 km s ^ { -1 } wrt .
the centre of the nebula .
Assuming undecelerated expansion , this expansion speed implies that the age of G21.5 - 0.9 is 870 ^ { +200 } _ { -150 } yr , which makes PSR J1833 - 1034 one of the youngest , if not the youngest , known pulsars in the Galaxy .