  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 the
pre-perihelion leg of comet ISON. 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/s, 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.
