The passes of the Transit or Navy Navigation Satellite System (NNSS) satellites have been recorded at stations operated by the University of Queensland Space Physics Group for some years. The development of digital recording systems and computer controlled processes have enabled the group to collate a significant store of information, the period June 1992 to June 1996 of which has been analysed. The data may be requested by interested parties by e-mailing the group care of Dr. Lech Hajkowicz.
The catalogue of recorded passes has been broken into year groupings. A
labelling system has been devised to describe the approximate location of the irregularities
thought to be responsible for the scintillations that is numerically based.
The use of the labelling system is correlated with the descriptors for
mid-latitude scintillations that has been described elsewhere in these pages.
Briefly, the labelling system has three numbers:
The first number stands for the type of scintillation (4 - QP type, 3 - N or P type,
2 - PS type, 1 - S type), the second number is relatively meaningless and
the third indicates the relative distance from the magnetic zenith point.
Some examples are
321 = scintillation patch close to magnetic zenith
322 = scintillation patch north further from zenith, 323 etc. indicate patches further north
221 = scintillation patch close to zenith but south
119 = scintillation region well south of Brisbane (just visible over the southern horizon)
118,117,116 indicate scintillation regions extending further towards Brisbane
421= QP scintillation
Furthermore, the records have been catagorized to evaluate the relative disturbance in the received signal using the SI index. The numbers are roughly equivalent to percentage disturbance figures ie. 0 = 0%, 1 = 20%, .., 5 = 100%.
Passes: June 1992 to June 1993
Passes: June 1993 to June 1994
Passes: June 1994 to June 1995
Passes: June 1995 to June 1996
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Last updated 29/12/1997 by Mark Keir