A deeper look at the GD1 stream: density variations and wiggles
  Using deep photometric data from CFHT/Megacam, we study the morphology and
density of the GD-1 stream, one of the longest and coldest stellar streams in
the Milky Way. Our deep data recovers the lower main sequence of the stream
with unprecedented quality, clearly separating it from Milky Way foreground and
background stars. An analysis of the distance to different parts of the stream
shows that GD-1 lies at a heliocentric distance between 8 and 10 kpc, with only
a shallow gradient across 45 deg on the sky. Matched filter maps of the stream
density show clear density variations, such as deviations from a single orbital
track and tentative evidence for stream fanning. We also detect a clear
under-density in the middle of the stream track at $\varphi_{1}$=-45 deg
surrounded by overdense stream segments on either side. This location is a
promising candidate for the elusive missing progenitor of the GD-1 stream. We
conclude that the GD-1 stream has clearly been disturbed by interactions with
the Milky Way disk or other sub-halos.
