  We observed the afterglow of GRB 130427A with the RATIR instrument on the
1.5-m Harold L. Johnson telescope of the Observatorio Astron\'omico Nacional on
Sierra San Pedro M\'artir. Our homogenous $griZYJH$ photometry extends from the
night of burst to three years later. We fit a model for the afterglow. There is
a significant positive residual which matches the behavior of SN 1998bw in the
$griZ$ filters; we suggest that this is a photometric signature of the
supernova SN 2013cq associated with the GRB. The peak absolute magnitude of the
supernova is $M_r=-18.43\pm0.11$.
