It had expanded to greater than 2 degrees of arc as seen from Earth, and thus had very little surface brightness. Notably the comet 17P/Holmes dust trail from the 2007 outburst repeatedly converges at the original site. An outburst of 3–4 magnitudes occurred in January 2015, but still required a large telescope to be seen. References External links 17P at Cometary Science Center 17P at Kronk’s Cometography 17P at Kazuo Kinoshita's Comets 17P at Seiichi Yoshida's Comet Catalog Magnitude graph for 2007-2009 Enigmatic Comet Holmes by Jeff Bryant, The Wolfram Demonstrations Project. Evolution of Comet 17P/Holmes Obscure Comet Brightens Suddenly Quick Facts About Comet Holmes Simple Instructions on How to Find Comet Holmes Instructions for the Amateur-based around Toronto or New York. 17P at Las Cumbres Observatory (22 Jan 2010 11:57, 223 seconds) Hubble Zooms In on Heart of Mystery Comet (Hubblesite STScI-2007-40 : November 1, 2007) NASA's Spitzer Gets Sneak Peek Inside Comet Holmes (October 13, 2008) Periodic comets 0017 20071023 Comets in 2014 18921106