Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on 7 August 2006 by British-Australian astronomer Robert H. McNaught using the Uppsala Southern Schmidt Telescope. It was the brightest comet in over 40 years, and was easily visible to the naked eye for observers in the Southern Hemisphere in January and February 2007. With an estimated peak magnitude of −5.5, the comet was the second-brightest since 1935. Around perihelion on 12 January, it was visible worldwide in broad daylight. Its tail measured an estimated 35 degrees in length at its peak. The brightness of C/2006 P1 near perihelion was enhanced by forward scattering. Discovery McNaught discovered the comet in a CCD image on 7 August 2006 during the course of routine observations for the Siding Spring Survey, which searched for Near-Earth Objects that might represent a collision threat to Earth. The comet was discovered in Ophiuchus, shining very dimly at a magnitude of about +17. From August through November 2006, the comet was imaged and tracked as it moved through Ophiuchus and Scorpius, brightening as high as magnitude +9, still too dim to be seen with the unaided eye. Then, for most of December, the comet was lost in the glare of the Sun. Upon recovery, it became apparent that the comet was brightening very fast, reaching naked-eye visibility in early January 2007. It was visible to northern hemisphere observers, in Sagittarius and surrounding constellations, until about 13 January. Perihelion was 12 January at a distance of 0.17 AU. This was close enough to the Sun to be observed by the space-based Solar and Heliospheric Observatory (SOHO). The comet entered SOHO's LASCO C3 camera's field of view on 12 January, and was viewable on the web in near real-time. The comet left SOHO's field of view on 16 January. Due to its proximity to the Sun, the Northern Hemisphere ground-based viewers had a short window for viewing, and the comet could be spotted only during bright twilight. As it reached perihelion on 12 January, it became the brightest comet since Comet Ikeya–Seki in 1965. The comet was dubbed the Great Comet of 2007 by Space.com. On 13 and 14 January 2007, the comet attained an estimated maximum apparent magnitude of −5.5. It was bright enough to be visible in daylight about 5°–10° southeast of the Sun from 12