New Comet: C/2011 S1 (GIBBS)

Cbet nr.2822, issued on 2011, September 21, announces the discovery of a new comet (discovery magnitude 21.2) by A. R. Gibbs on CCD images obtained on September 18, 2011 by Gibbs and S. F. Tornero with the Mt. Lemmon 1.5-m reflector. The new comet has been designated C/2011 S1 (GIBBS).

During the same observing session, we noticed also the presence of a new fragment, not visible on our past images obtained with the same set-up (the last of which dates back 2011, Sep. 2.5): this additional fragment (that we called below "part-y") appears slightly brighter and compact than 0213Pb itself (m1 about 21.0, coma diameter about 4-arcsec elongated toward the southwest). "part-y" was located about 4.5 arcmin in PA 239 respect the main nuclear condensations of 213P/Van Ness.

M.P.E.C. 2011-S28 assignes the following preliminary orbital elements to comet C/2011 S1 (GIBBS): 2013 Jan. 16.54; e= 1.0; Peri. =174.65; q = 4.99 AU; Incl.= 2.23

by Giovanni Sostero, Nick Howes and Ernesto Guido