View source for File talk:Vlcsnap-2011-08-29-23h40m41s254.jpg

probably more a Su-9 (note the pitot tube on the left wing outside the missiles; on the Mig 21, it's only on the nose); this plane seems to have two underbelly tanks side by side (a single one if it's a Mig 21)

compare the three view drawings :
Su-9  http://www.aviastar.org/pictures/russia/su-9b.gif
Mig 21 http://richard.ferriere.free.fr/3vues/mig21mf_3v.jpg