COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XV.
  Assessing the achievability and precision of time-delay measurements
  COSMOGRAIL is a long-term photometric monitoring of gravitationally lensed
QSOs aimed at implementing Refsdal's time-delay method to measure cosmological
parameters, in particular H0. Given long and well sampled light curves of
strongly lensed QSOs, time-delay measurements require numerical techniques
whose quality must be assessed. To this end, and also in view of future
monitoring programs or surveys such as the LSST, a blind signal processing
competition named Time Delay Challenge 1 (TDC1) was held in 2014. The aim of
the present paper, which is based on the simulated light curves from the TDC1,
is double. First, we test the performance of the time-delay measurement
techniques currently used in COSMOGRAIL. Second, we analyse the quantity and
quality of the harvest of time delays obtained from the TDC1 simulations. To
achieve these goals, we first discover time delays through a careful inspection
of the light curves via a dedicated visual interface. Our measurement
algorithms can then be applied to the data in an automated way. We show that
our techniques have no significant biases, and yield adequate uncertainty
estimates resulting in reduced chi2 values between 0.5 and 1.0. We provide
estimates for the number and precision of time-delay measurements that can be
expected from future time-delay monitoring campaigns as a function of the
photometric signal-to-noise ratio and of the true time delay. We make our blind
measurements on the TDC1 data publicly available
