Satgen243 HF Satellite DX via Auroral Hop Propagation by GM4IHJ 20Nov 93 BIB of this msg is SGEN243 Please use this BIB if you retransmit this msg In 1990 I wrote in the RSGB Space Radio Handbook - " There is no evidence of Auroral Es ( through the aurora propagation), affecting signals from space". Events in October and November 93 have totally destroyed that view. With up to 10 29MHz satellite orbits over the Arctic on a single day, being heard 2000 kms or more beyond the UK northern horizon. A situation which if you add up the UK RS12 horizon of 3300 kms, plus a 2000 kms extension via a hop through the Auroral oval, to a satellite which can then see a further 3300 kms from its position up at 1000 kms height, you get a reach of over 8000 kms from UK inside which RS12 DX is possible. The actually geographic coverage depends on the satellite track , but in the course of one Auroral afternoon and evening, DX possibilities covered Japan, Korea, Siberia, All USA, Alaska and Canada plus Northern Mexico . The 18th Nov 93 was a typical day. There was no warning except that the October solar disturbance which gave several good "Auroral " days was coming around again , when at :- 1417 RS10's 29.358 beacon was heard off the North shore of Alaska. At 1540 ut GB7LER VHF beacon on Shetland went auroral . 1549 RS12 came up from 70N 106W ie seeing Chicago, St Louis, Oregon , all Canada and Alaska. 1723 the next RS12 pass was heard from 63N 135W ie seeing Western USA, Mid and Western Canada and all Alaska. By contrast the 1923 ut pass of RS12 had no sub horizon extension - a blank which appears to occur in Auroras of this Kp4 Kp3 size at around this time, which may be related to the unfavourable position of the Harang discontinuity in the pattern of the Auroral circulation currents. 2104 ut RS12 appeared when over 72N 183W ie seeing Alaska, Siberia and Northern Japan. Then at 2247 an orbit which came nowhere near UK was none the less heard as it tracked from Asia 66N 216W to USA 50N 65W. This continuous track covered everything from Northern Japan , up past Alaska and the down into Canada and Central USA as far as the northern provinces of Mexico. So what does this add up to for would be sat DXers. We had similar aurora and similar blocks of useful DX orbits on Oct 25, and November 14th and 18th, while Oct 26 and 27 plus November 1 and 4, had weaker aurora Kp3 at best and produced one or two extended orbits.The rules seem to be that :- 1. Operate during and after terrestrial vhf propagating aurora, any time of day after 1400 local. 2. Use CW. THe signal is rarely good enough for SSB . 3. Listen for RS10 29.358 and RS12 29.408 MHz beacons even when the satellites are up to 22 degrees below your polar horizon. 4. Be clear in your mind that Auroral hop only works when you view the satellite through the auroral oval. 5. On most nights even when previous orbits had good extensions, orbits around 1930 local usuallly lack any sort of extension. But by about 2000 orbit extensions begin again and can be very good around midnight even on orbits which never come within 1000 kms of UK. 6. Be aware this afternoon and evening Auroral Hop is quite a different propagation mode from the "midday" HF F layer plasma injection propagation discovered by Bob NM7M Checks of terrestrial beacons to your north inside the auroral oval can be useful OH9TEN is the best Auroral hopper at GM4IHJ. If you want to see graphic tracks of Auroral hop sat orbit. SASE me QTHr. 73 GM4IHJ@GB7SAN