title: Estimating small time shift between two time series
body: <p>I have two time series, and i suspect that there is a time shift between them, and i want to estimate this time shift.</p>
  
  <p>This question has been asked before in:
  <a href="https://stackoverflow.com/questions/6157791/find-phase-difference-between-two-inharmonic-waves">Find phase difference between two (inharmonic) waves</a> and <a href="https://stackoverflow.com/questions/4688715/find-time-shift-between-two-similar-waveforms">find time shift between two similar waveforms</a> but in my case, the time shift is smaller than the resolution of the data. for example the data is available at hourly resolution, and the time shift is only few minutes(see image).</p>
  
  <p>The cause of this is that the datalogger used to measure one of the series has few minutes shift in its time.</p>
  
  <p>Any algorithms out there that can estimate this shift, preferably without using interpolation?</p>
  
  <p><img src="https://i.stack.imgur.com/t52b8.png" alt="solar irradiation forecast and solar irradiation measurement"></p>