Measurement of the Cosmic Optical Background using the Long Range
  Reconnaissance Imager on New Horizons
  The cosmic optical background is an important observable that constrains
energy production in stars and more exotic physical processes in the universe,
and provides a crucial cosmological benchmark against which to judge theories
of structure formation. Measurement of the absolute brightness of this
background is complicated by local foregrounds like the Earth's atmosphere and
sunlight reflected from local interplanetary dust, and large discrepancies in
the inferred brightness of the optical background have resulted. Observations
from probes far from the Earth are not affected by these bright foregrounds.
Here we analyze data from the Long Range Reconnaissance Imager (LORRI)
instrument on NASA's New Horizons mission acquired during cruise phase outside
the orbit of Jupiter, and find a statistical upper limit on the optical
background's brightness similar to the integrated light from galaxies. We
conclude that a carefully performed survey with LORRI could yield uncertainties
comparable to those from galaxy counting measurements.
