The map is auto-refreshed approximately once per minute. It’s generated by the application LiveMUF by Dave Edwards, G7RAU. This application is available to licenced radio amateurs to produce their own propagation maps.
Yellow arcs signify auroral reflection zones for the stations reporting auroral contacts.
White closely spaced arcs = “Iso Reflections”
White parallel lines crossing the map = day/night terminator
Yellow star = Sub-solar point
The data block in the bottom left corner includes the date and the start/end times for the 30 minute period of the current map in UTC.
[ Short link to this page: http://bit.ly/1NLKB18 ]
When an auroral radio contact is reported by an amateur radio operator via the DX Cluster network (a network of packet radio and Telnet internet connections), the report is received by my Live MUF sotware in the form
[ SPOTTER CALLSIGN ] [ FREQ in kHz ] [ DX CALLSIGN ] [ SPOTTER LOC’N ]
(PROPAGATION MODE > [ DX LOC’N ] [ SIGNAL REPORT ] [ TIME-DATE ]
Once logged into the system, the operator only sends the DX callsign, frequency, mode and signal report. The software can look up the locations of both operators and fill in the time. The following is a real DX Cluster report of auroral mode propagation received on Oct 12th 2015:
GM4JJJ 144300.0 GM0HTT IO86GB(AUR>IO89JC 57A 1852 12 Oct 2015
The Live MUF software evaluates the report as an auroral contact, and calculates the likely reflection “point” and suitable angles based on the locations and relative distances between the SPOTTER and the DX locations. Locations used are based on the Maidenhead locator system, which is widely used by radio amateurs.
On the map we see red dots denoting SPOTTERS and DX locations, and red lines joining them – not directly, but via an estimated “reflection point” which will be the rough location of the auroral curtain.
A broad yellow arc will also be drawn on the map for each contact, which, based on the current data, shows the extent of the auroral influence. As more contacts are added over a period of a few minutes, the arcs will begin to overlap, giving a better idea of how widespread the aurora is. The shapes of the arc may vary as more data becomes available.
Additionally some white arcs (called iso-reflections) are drawn on the map. (I am awaiting a fuller explanation of what an iso-reflection is in this context before writing it here). It presents what looks like a “wave-front” which might suggest the most southerly edge from where aurora might be observed or used or have some influence over radio signals. I’m experimenting with these settings and they may change as I learn more about them.