We test a sample of satellites of isolated primary galaxies , extracted from the 2dF Galaxy Redshift Survey ( 2dFGRS ) , for any tendency to be aligned along ( or against ) the primary-to-satellite radius vector .
If tidal effects induce such an alignment , it would contaminate recent measurements of galaxy halo masses which use the coherent alignment induced on background galaxies by gravitational lensing .
The mean tangential ellipticity of 1819 satellites within 500 kpc projected radius is \langle e _ { + } \rangle = +0.004 \pm 0.008 , so no tidal alignment is detected .
This implies at 95 % confidence that satellite alignment is less than a 20 % contamination of the alignment signal attributed to galaxy-galaxy lensing by Smith et al . ( 2001 ) and McKay et al . ( 2001 ) .