Introduction to general relativity in a setting with comparatively strong gravitational fields. This has become possible thanks to precision observations of binary pulsars. In such a star system, two highly compact neutron stars orbit each other. At least one of them is a pulsar – an astronomical object that emits a tight beam of radiowaves. These beams strike the Earth at very regular intervals, similarly to the way that the rotating beam of a lighthouse means that an observer sees the lighthouse blink, and can be observed as a highly regular series of pulses. General relativity predicts specific deviations from the regularity of these
POlarization Emission of Millimeter Activity at the Sun of observing at 45 and 90 GHz comes from the necessity to determine the "upturn" frequency in the so-called "THz events": if the main radiation mechanism is synchrotron radiation from accelerated electrons emitting at chromospheric or coronal heights, it is expected a spectrum with a long and descending logarithmic tail towards millimeter wavelengths. In some cases this classical ("textbook") shape is broken and an "upturn" or "spectral reversion" is observed. Since the reversion or "upturn" frequency has been estimated around 50 to 100 GHz for the observed cases, the importance of POEMAS is justified. POlarization Emission of Millimeter Activity at