  The existence of cosmic superstrings may be probed by astronomical time
domain surveys. When crossing the line of sight to point-like sources, strings
produce a distinctive microlensing signature. We consider two avenues to hunt
for a relic population of superstring loops: frequent monitoring of (1) stars
in Andromeda, lensed by loops in the haloes of the Milky-Way and Andromeda and
(2) supernovae at cosmological distances, lensed by loops in the intergalactic
medium. We assess the potential of such experiments to detect and/or constrain
strings with a range of tensions, $10^{-15} \lesssim G \mu/c^2 \lesssim
10^{-6}$. The practical sensitivity is tied to cadence of observations which we
explore in detail. We forecast that high-cadence monitoring of $\sim 10^5$
stars on the far side of Andromeda over a year-long period will detect
microlensing events if $G\mu/c^2 \sim 10^{-13}$, while $\sim 10^6$ stars will
detect events if $10^{-13.5} <G\mu/c^2 < 10^{-11.5}$; the upper and lower
bounds of the accessible tension range continue to expand as the number of
stars rises. We also analyse the ability to reject models in the absence of
fluctuations. While challenging, these studies are within reach of forthcoming
time-domain surveys. Supernova observations can hypothetically constrain models
with $10^{-12} < G\mu/c^2 < 10^{-6}$ without any optimisation of the survey
cadence. However, the event rate forecast suggests it will be difficult to
reject models of interest. As a demonstration, we use observations from the
Pantheon Type Ia supernova cosmology data-set to place modest constraints on
the number density of cosmic superstrings in a poorly tested region of the
parameter space.
