Satgen 573 RS13 Auroral Explorer by GM4IHJ (BID SGEN573) 2000-03-18 The steady stream of ionised particles we call the solar wind, is continuously colliding with the earths magnetic field , and being diverted by it over the earths magnetic poles. Above the poles the earths magnetic field lines are vertical. So while some of the solar wind moves on into the magneto tail behind the earth, some of it descends down between the field lines to collide with the atmosphere above and around the magnetic poles. The effect of this in the normal quiescent state of the solar wind, is the creation of an ellipse of ionised material around each of the magnetic poles between 80 and 500 kms above the earth and perhaps 1500 to 2500 kms out from the poles. Even in quiet solar wind states the auroral oval thus generated is moving relative to your station as the earth with you on it turn under it .At Local Magnetic Noon ( when a line from the Sun through your station goes on to pass over the magnetic pole ), the oval is pushed away from your station by the solar wind towards the pole. By contrast at Local Magnetic Midnight ( when a line from your station goes through the magnetic pole to hit the Sun on the far side of the globe from you ), the auroral oval is pushed towards you. Reaching its lowest latitude that day nearest your station. So there is a cyclic change through the day and night as the oval recedes from you then as night approaches comes towards you. This already complex picture is further complicated by the seasons of the year. As the earths rotation axis is tilted with respect to its orbit plane around the Sun, so the Sun moves north in the northern summer , south in the northern winter. Thereby altering the UTC time at which your local magnetic midday and midnight occur. Even worse the solar wind is highly variable . In solar storms the auroral oval expands outwards towards the equator, away from the poles So in practice you must consider all these variables if you wish to study the aurora. But you can plot where the auroral oval is through the day and night if you have a receiver for RS13s 29.458 MHz CW beacon . You can listen for the familiar double signals when RS13 is near or inside the auroral oval . One signal T6 to T8 direct, the other T1 to T3 off the auroral oval. If you have FFT audio spectrum analysis software , you can see these signals on your display. As RS nears the the edge of the oval you may depending on your Latitude pick up a T2 signal 550 Hz above, the direct signal from the satellite at T8. Gradually the T2 signal dopplers to meet the direct signal , as RS13s position changes with respect to the oval. Depending on your station latitude ie above 56N in Europe, above 46N in America you should see both signal for a time . Stations further south however are likely to have the auroral signal only rarely . Similar conditions may apply in southern hemisphere. Favouring southern VK/ZL, because of the location of their mag pole.