Peranso allows to measure the distance between two observations in an Observations Window or Phase Window. The distance will be expressed in the unit of the X-axis and Y-axis. Assume we have an ObsWin with a light curve expressed in Julian date (X-axis) and Magnitude (Y-axis). The  Measurement indicator will then display the difference in Julian date between the two observations, as well as the difference in Magnitude.

To measure the distance, move the mouse to the first data point in your ObsWin or PhaseWin. Hold the Ctrl button and meanwhile click and hold the left mouse button. A rubberband line appears showing the measured distances, near the mouse position. Release the left mouse button to stop measuring.

The measured distances string appears either in regular font or in bold font. Bold font is used when both the start- and endpoint of the Measurement indicator correspond with an observation in the ObsWin or PhaseWin.

ObsWin showing the Measurement indicator as a blue line. The value of 0.0226 day is the time difference between the observation at the start and at the end of the indicator. The value of 0.02 is the magnitude difference.