We present discovery images , together with follow-up imaging and spectroscopy , of two large separation gravitational lenses found by our survey for wide arcs ( the CASSOWARY ) .
The survey exploits the multicolour photometry of the Sloan Digital Sky Survey to find multiple blue components around red galaxies .
CASSOWARYÂ 2 ( or “ the Cheshire Cat ” ) is composed of two massive early-type galaxies at z = 0.426 and 0.432 respectively lensing two background sources , the first a star-forming galaxy at z = 0.97 and the second a high redshift galaxy ( z > 1.4 ) .
There are at least three images of the former source and probably four or more of the latter , arranged in two giant arcs .
The mass enclosed within the larger arc of radius \sim 11 ^ { \prime \prime } is \sim 33 \times 10 ^ { 12 } { { { M _ { \odot } } } } .
CASSOWARYÂ 3 comprises an arc of three bright images of a z = 0.725 source , lensed by a foreground elliptical at z = 0.274 .
The radius of the arc is \sim 4 ^ { \prime \prime } and the enclosed mass is \sim 2.5 \times 10 ^ { 12 } { { { M _ { \odot } } } } .
Together with earlier discoveries like the Cosmic Horseshoe and the 8 O ’ Clock Arc , these new systems , with separations intermediate between the arcsecond separation lenses of typical strong galaxy lensing and arcminute separation cluster lenses , probe the very high end of the galaxy mass function .