Satgen105    Aurora and Satellites  by GM4IHJ     2nd April 91

At the Magnum rally at Irvine on 24th March , Doug GM4DJS mentioned that
there had been a monster magnetic storm at 0300ut that day, and he warned
of the high possibility of a big aurora that night . As most folks will
know the big aurora duly appeared . I saw the best visual aurora I have
seen in 4 years , and even though the Polar Front had moved south of my
56N latitude ( which reduces auroral performance from GM ) I was able to
indulge my continuing study of the effects of aurora on satellites on both
the big event of the 24th and the smaller event of pm 25th. Results here
in GM for these and other auroras of the last 14 years show that:-

1. If an HF or a VHF sat is south of me when the polar front is south of
my station, I get double signals from the sat beacons and users . One
signal nearly clear T7 or 8, the other, about 100Hz separation at 29MHz or
400Hz separation at 145MHz T2 to 4 at best. Sats to my north have
completely clear signals plus a displaced T2 to T4 signal.

2.  Normally aurora is well to my north, but if the aurora comes above my
horizon it again provides a duet, one clear one and one T3 or T4 signal
provided the satellite is south of the aurora. If however the satellite is
north of the aurora ie its signal reaches me through the aurora as is
often the case with Fuji Oscar 20 on 70cms , I get a very mangled signal
which scintillates very badly and despite have a reasonably clear T8 tone
the signal is so chopped up , that CW is almost impossible to read.

3. Even when the polar auroral oval is quiet and there is no auroral sign
above  my northern horizon , I can still get only poor quality signals
from Fuji Oscar 20, but at times I get freak reception of AO13 from
Canada, getting nothing direct from AO13 mode B on my receive antenna
unless I aim 30 or 40 degrees off the satellite  at which point I
sometimes get a very T3 signal.

4. Looking south from my northern station I used to think I was too far
north to get the Equatorial FAI mode T4 to T5 signals reported between SV
and ZS , and, KP and LU. But after a lot of HF listening around 1986 and
since then I seem to get "Middle latitude T4 signals " on quite a number
of RS 29MHz signals, although I have'nt noticed this on southerly VHF sats

So whether you have a local aurora or not , please listen for , and make a
note of any of these rough note signals you hear from satellites. The
Propagation and the Experiment sections of the forthcoming RSGB Space
Radio Handbook ( publishing 28 April) has lots more detail on these
phenomena.

DOVE.  I do not presently know what has happened to Dove . After getting a
megabyte of Dove Arctic passes for G3ZCZ/W3 up to 23rd March , I have lost
it on 145.825. Must remember to look on 2401MHz to see if it is there.
73 de John GM4IHJ @ GB7SAN