BIRO Spectrograph Files

April 28, 2008 UTC

The following images are from an Io-C storm observed at the Big Island Radio Observatory by Jim Sky.
Longitude: 155.75 W   Latitude: 19.2 N
Receiver: SDR-14
Antenna: 8 element wire Log Periodic
Software: Modified version of the Radio-Sky Publishing Spectrograph software.

Times are in UTC. Notice not all charts have exactly the same duration.  Also note that charts after 15:51 display a lower frequency range. Io-C storms are known to occur at lower frequencies.  There are some gaps in time between some charts as a software problem required restarting the program many times. Corresponding comments appear below some charts. This storm seemed to occur primarily in narrow bands of drifting emission, except during the last hour when wider bands were observed. The occasional thin vertical spikes across the charts are distant lightning (example; about 15:19:13). The smooth darker region below about 20 MHz is due primarily to greater sensitivity of the system in that region.


Strong narrow band emission. Perhaps, 'N' bursts.

Radio station interference begins just above 17 MHz. The sun is rising and supporting this type of signal. This station is present as a very straight line through the rest of the storm. Do not confuse this with less regularly shaped Jupiter emissions.

Broader regions of emission are clear in this portion of the storm.

Notice these broad regions of emission are descending at about 3kHz/sec.

Another station begins to pop into view just below 18 MHz.

Last vestiges of descending emission die out around 1700 UTC.