The term Cadence is often used for the period
(or frequency) of periodic observations. It
may (incidentally) roughly equal the time between observations, e.g.,
when a 5-second observation is made every 30 minutes,
or the exposure time of individual "snapshots",
in the case where something is being observed continuously,
but CCD "counts" are stored periodically.
This use of the term is common when Transients
are being searched for or observed, such as
Transits, Gravitational Microlensing, or Radial Velocity indications.