We present the results of a global coma morphology campaign for comet C/2012 S1 (ISON), which was
organized to involve both professional and amateur observers. In response to the campaign, many
hundreds of images, from nearly two dozen groups were collected. Images were taken primarily in the
continuum, which help to characterize the behavior of dust in the coma of comet ISON. The campaign
received images from January 12 through November 22, 2013 (an interval over which the heliocentric
distance decreased from 5.1 AU to 0.35 AU), allowing monitoring of the long-term evolution of coma
morphology during comet ISON's pre-perihelion leg. Data were contributed by observers spread around
the world, resulting in particularly good temporal coverage during November when comet ISON was
brightest but its visibility was limited from any one location due to the small solar elongation. We
analyze the northwestern sunward continuum coma feature observed in comet ISON during the first half
of 2013, finding that it was likely present from at least February through May and did not show variations
on diurnal time scales. From these images we constrain the grain velocities to 10 m s1
, and we find
that the grains spent 2–4 weeks in the sunward side prior to merging with the dust tail. We present a
rationale for the lack of continuum coma features from September until mid-November 2013, determining
that if the feature from the first half of 2013 was present, it was likely too small to be clearly
detected. We also analyze the continuum coma morphology observed subsequent to the November 12
outburst, and constrain the first appearance of new features in the continuum to later than November
13.99 UT.
Nalin H. Samarasinha a,n , Beatrice E.A. Mueller a , Matthew M. Knight b , Tony L. Farnham c , John Briol d , Noah Brosch e , John Caruso f , Xing Gao g , Edward Gomez h , Tim Lister h , Carl Hergenrother i , Susan Hoban j , Roy Prouty j , Mike Holloway k , Nick Howes l , Ernesto Guido l , Man-To Hui m, Joseph H. Jones n , Tyler B. Penland n , Samuel R. Thomas n , Jim Wyrosdick n , Nikolai Kiselev o , Aleksandra V. Ivanova o , Thomas G. Kaye p , Jean-Baptist Kikwaya Eluo q , Betty P.S. Lau r , Zhong-Yi Lin s , José Luis Martin t , Alexander S. Moskvitin u , Martino Nicolini v , Brian D. Ottum w, Chris Pruzenski x , David C. Vogel x , Leo Kellett x , Valerie Rapson x , Joel Schmid x , Brandon Doyle x , Frank Dimino x , Stephanie Carlino x , Margarita Safonova y , Jayant Murthy y , Firoza Sutaria y , David G. Schleicher b , Colin Snodgrass z , Cihan T. Tezcan aa, Onur Yorukoglu aa, David Trowbridge bb, Dennis Whitmer cc, Quan-Zhi Ye dd
t Carpe Noctem Observatory, Spain
Full paper here.
