Jonathan Sick, Queen's University

Near-Infrared Imaging of the Andromeda Galaxy by ANDROIDS with WIRCam

We present the first accurately-calibrated mapping of the Andromeda
Galaxy's disk with CFHT/WIRCam.  Our J and Ks maps allow resolved
stellar populations to be contrasted with the near-infrared (NIR)
surface brightness. A major hurdle in deriving an accurate NIR picture
for such a large object on the sky is the rapidly changing NIR sky. We
demonstrate the severity of the temporal and spatial variations of the
NIR sky background, and present a novel sky-target nodding scheme used
to control both level and shape variations of sky to within 1% of the
sky brightness.  Even finer control of the background is achieved by
considering the surface brightness continuity across WIRCam
fields. This work is part of ANDROIDS: the Andromeda Optical &
Infrared Disk Survey with CFHT MegaCam and WIRCam.  ANDROIDS will
ultimately cover the disk of Andromeda out to 40 kpc in the
u*g'r'i'JKs bands. Together with CFHT's PAndAS and HST/PHAT's
complementary surveys of Andromeda, ANDROIDS will provide an
unprecedented, global view of a galaxy's detailed structure and
stellar populations.