Comet C/2011 L4 (PanStarrs): Small nucleus, fast rotator and dust rich comet observed after perihelion [EPA]

http://arxiv.org/abs/1608.01243


Orbital elements of C2011 L4 (PanStarrs) Oort cloud comet, computed by MPC (Minor Planet Center, Minor Planet Electronic Circular 2012-T08), show that the closest approach to the Sun occurred on 2013 March 10th, at about 0.3 A.U., then about 4,51×10^7 km. Discovered by Richard Wainscoat (Institute for Astronomy, University of Hawaii) on four CCD images taken with the 1.8-m “Pan-STARRS 1” telescope at Haleakala taken on 2011 June 6th. My first observation of the comet was on 2013 March 10th whit the comet visible in the twilight. I did the following visual estimation; Mar. 10.73,-1.0*,5′(T. Scarmato, Calabria, Italy, 7×50 binoculars; altitude 7 deg, tail 1 deg in pa 140 deg), reported to the ICQ (International Comet Quarterly). Easy comet in 7×50 binoculars I started to see C/2011 L4 at 18:35 L.T. when the comet was at about 7{\deg} above the horizon. I saw a tail long about 1,5{\deg} in pa 140{\deg} with a coma well condensed and large about 5′. I followed the comet until to the set at 18:55 L.T., still clearly visible at so low altitude about 1{\deg} or less! I don’t saw Mars (1.39 mag) at the same altitude, so I esteemed the comet using Aldebaran (1.1 mag) at 62,44{\deg} of altitude also using the ICQ Table of Atmospheric Extinction; but remembering C/2006 P1 in the same conditions of observation I could to assume that the comet was at negative apparent total magnitude m1= -1.0. The image of the comet was impressive (see Fig. 2). Here, I present my observations and results on the size of the nucleus, period of rotation, dust production and peculiar structures in the inner coma.
Key words: General: general; comets: C/2011 L4 (PanStarrs), PanStarrs, comets, afrho, photometry of aperture, flux, apparent magnitude, absolute magnitude; comet nucleus: size, rotation.

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T. Scarmato
Thu, 4 Aug 16
9/70

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