Ionospheric scintillation 25 & 27.12.2013

Ionospheric scintillation is the variation in the amplitude and phase of radio signals as they pass through the ionosphere. What is happening is small-scale variations in the electron density result in differences in the ionosphere's refractive index at radio-frequencies. It is sort of the radio equivalent of the "twinkle of stars". The localised variations in refractive index cause momentary focusing, defocusing or shifting of the incoming radio waves. For broad, diffuse structures in the sky (like the synchrotron emission from the Galaxy) all of these effects average out for different directions. But for a point-source (such as bright "radio stars") the singular line-of-sight can result in dramatic differences.

This short video shows approximately 5 minutes of data from two separate days. The all-sky radio images were both made using the KAIRA facility, located in Arctic Finland. The observing frequency was the same in both cases 58.594 MHz), 1 second
integration per frame, 195.3 kHz bandwidth. The time of day was also the same, so the radio sky is in roughly the same orientation.

On the 25.12.2013 (left), the ionosphere exhibited extreme scintillation. The two bright sources (Cas A and Cyg A) are flickering quite dramatically. However, exactly two days later (27.12.2013, right), the ionosphere was relatively stable and the brightnesses of the two strong radio sources remain steady.

Note: There is no audio with this video.