sentences:  On 15 March 2007, Lovejoy used a standard camera to discover the comet C/2007 E2 (Lovejoy).Two months later, he discovered another comet, designated C/2007 K5 (Lovejoy) using the modified camera.On 27 November 2011, with his discovery of C/2011 W3 (Lovejoy), he became the first astronomer in over 40 years to discover a Kreutz Sungrazing comet from a ground-based observation.