(ACCEPTED FOR PUBLICATION IN The Astronomical Journal- REVISED: SEPTEMBER 8, 2011) Preprint typeset using LATEX style emulateapj v. 04/20/08 A PETAL OF THE SUNFLOWER: PHOTOMETRY OF THE STELLAR TIDAL STREAM IN THE HALO OF MESSIER 63 (NGC 5055)*

We present deep surface photometry of a very faint, giant arc-loop feature in the halo of the nearby spiral galaxy NGC 5055 (M63) that is consistent with being a part of a stellar stream resulting from the disruption of a dwarf satellite galaxy. This faint feature was first detected in early photographic studies by van der Kruit (1979); more recently by Martínez-Delgado et al. (2010) and as presented in this work, the loop has been realized to be the result of a recent minor merger through evidence obtained by wide-field, deep images taken with a telescope of only 0.16 m aperture. The stellar stream is clearly confirmed in additional deep images taken with the 0.5 m telescope of the BlackBird Remote Observatory and the 0.8 m telescope of the McDonald Observatory. This low surface brightness (µR ≈ 26 mag arcsec−2), arc-like structure around the disk of the galaxy extends 14.0 ′ (∼29 kpc projected) from its center, with a projected width of 1.6 ′ (∼3.3 kpc). The stream’s morphology is consistent with that of the visible part of a giant, “great-circle " type stellar stream originating from the recent accretion of a ∼108 M dwarf satellite in the last few Gyr. The progenitor satellite’s current position and final fate are not conclusive from our data. The color of the stream’s stars is consistent with dwarfs in the Local Group and is similar to the outer faint regions of M63’s disk and stellar halo. Through our photometric study, we detect other low surface brightness “plumes"; some of these ma