Original: On September 8 , 2001 , Titania occulted a bright star ( HIP106829 ) with a visible magnitude of 7.2 ; this was an opportunity to both refine the moon 's diameter and ephemeris , and to detect any extant atmosphere .
Simplified: On September 8 , 2001 , Titania occulted a faint star ; this was a chance to both refine its diameter and ephemeris , and to detect any extant atmosphere .