Comet C/2013 A1 and its close approach to Mars

The discovery of comet C/2013 A1 (SIDING SPRING) was announced on Cbet nr. 3368 & M.P.E.C. 2013-A14, issued on 2013, January 05. The comet was discovered on CCD images obtained by R. H. McNaught with the 0.5-m Uppsala Schmidt telescope on Jan. 03 (discovery magnitude 18.6). Precovery images of the comet by the Catalina Sky Survey from 8 December 2012 and Pan-STARRS from 4 October 2012 were subsequently found. C/2013 A1 will have a very close approach with planet Mars on October 19, 2014. With an observation arc of 148 days, JPL/NASA give a nominal closest approach of ~0.0003578 A.U. = 53,500 km on 2014 Oct. 19 at 19:28 +/- 1:03. The comet will pass Mars at a relative velocity of 56 km/s. Early estimates for the diameter of the nucleus have varied from 5 up to 50 km.Due to the uncertainty region, there is also a very small possibility that the comet may impact on planet Mars (~ from 0.1% to 0.01% according to how you handle the observations set. See here for more info about this). By comparison below you can find a table of the the closest known approaches to the Earth by comets published on Minor ...