Very Low Frequency Astronomy Or how to observe at work on a cloudy day!

The Radio Spectrum The VLF frequency range covers the same set of frequencies as our ears, except it is electromagnetic waves not air pressure waves

The Ionosphere VLF are opaque to the ionosphere Therefore VLF Astronomy is by its nature an indirect method of observing E Layer D Layer

Low level of Sky-wave signal Vs. ground-wave Quiet Sun Low level of Sky-wave signal Vs. ground-wave

Erratic level of Sky-wave signal Vs. Constant ground-wave At Night Erratic level of Sky-wave signal Vs. Constant ground-wave

High level of Sky-wave signal received during flare Active Sun High level of Sky-wave signal received during flare

Most people think radio astronomy think is complicated Colin Clements 4Ghz Radio Telescope But it doesn’t have to be...

Radio Equipment Antenna Receiver Recorder PC Larger the better More turns the better I have three 128 turns 400x400 square tuned antenna 25 turns 600mm Diameter circle un-tuned 150 turns 600mm diameter circle untuned Receiver Two approaches radio receiver tuned to a specific station, outputs signal strength PC sound card Recorder Two approaches Data logger PC

Data logger/controller My UKRAA VLF Receiver Antenna Aerial Tuning Unit Receiver Data logger/controller

Starbase Observatory Software

My Natural Radio Spectrum Set-up Antenna Soundcard

Live power spectrum, peaks are radio transmitters Waterfall shows how the power changes with time SpectrumLab Freeware Running on an old laptop Win98 (first Edition) 192MB RAM Pentium II 400MHz processor 6GB Harddisk Up to 100 plotters can be set to record the power at specific frequencies / bands of frequency

Radio Stations 19.6kHz GBZ, Anthorn,UK 20.27kHz ICV, Isola di Tavolara, Italy 20.9kHz FTA, Sainte-Assise, France 21.75kHz HWU, Rosnay, France 22.1kHz GQD, 22,.1kHz Skelton, UK 23.4kHz DHO38 Rhauderfehn, Germany 24Khz NAA, Cutler, Maine, USA 37.5kHz, NRK/TFK Grindavik, Iceland 62.6kHz, La Regine, France 81kHz, Inskip, UK

VLF receivers currently monitored

Recording & Interpreting Results Amplitude of event Corresponds (usually) to the flare class, but will be specific to conditions and observer Start, Peak & End of event Recorded as an importance level Class Energy X 10-4-10-3W/m2 M 10-5-10-4W/m2 C 10-6-10-5W/m2 B 10-7-10-6W/m2 A 10-8-10-7W/m2 Increasing Energy A text book SID Importance = 2+ 2011-02-28 12:46 – 12:54 – 13:48 Corresponded to a M1 event Duration Importance <18 min 1- 19-25 min 1 26-32 min 1+ 33-45 min 2 46-85 min 2+ 86 – 125 min 3 >126 min 3+

Transmitter is turned off at 07:00 – 08:00 every day Typical Quiet Day Transmitter is turned off at 07:00 – 08:00 every day

SID

Raw Data can be a little confusing

Removing signals after sunset and the signals that are not showing useful information can make it easier to see what is going on.

SIDs come in many shapes

Results

Next Steps for VLF Get laptop set-up in shed and connected via wifi to main PC Get lap-top controlling UKRAA controller Build VLF set-up for CMHAS observatory Experiment with different antenna configurations Automate logging and access via web

Future Projects for Radio Astronomy Meteor Detection Solar activity monitor (21Mhz) Radio Jove (21Mhz) Radio Imaging