Equinox Grey Line, Two Weeks Early
The grey line is the band of twilight that sweeps around the earth, and for about half an hour either side of local sunrise and sunset the lower shortwave bands open along it in ways they never do at midday. Signals that are normally buried come up out of the noise, peak for a few minutes, and sink again. I have known this for two years and still find it slightly miraculous every time it works.
This week I set the alarm for 04:30 UTC, which is just before sunrise here in early September, and sat on the balcony with the receiver and a flask. The 75 and 60 metre bands were the interesting ones. At 04:41 a station on 4,840 kHz came up from nothing to a readable signal with a religious programme in English, clearly from across the Atlantic, and faded back into the hiss by 04:58. At 04:52 there was Portuguese on 4,885 kHz, very weak, music and then a man speaking quickly; I could not identify the station but the direction of the fade suggested South America. On 60 metres, 5,025 kHz carried a Cuban station with slow music and a woman announcing between the songs.
What interests me is that these catches are two weeks before the equinox itself. The textbooks say the equinox weeks are the best for grey line work because the terminator runs nearly north to south and the paths line up, and I had assumed the effect would build gradually. Instead it has come on almost like a switch since the end of August, after a summer in which the same frequencies at the same time gave me nothing but static.
Logging on the balcony has its own problems. The flask cools quickly, the neighbours’ kitchen light comes on at 05:10 and brings a buzz across the whole band, and writing in a notebook by the light of the receiver display is slow. I have started recording the audio on a small digital recorder so that I can go back and listen for identifications at a sensible hour, which has already resolved two stations I would otherwise have logged as unidentified.
The plan is to keep the dawn sessions going three mornings a week through to mid-October, when the clocks change and the sunrise slips later, and then switch to the evening grey line, which is kinder to sleep.