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

2. 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

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

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

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

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

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

8. 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

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

10. Starbase Observatory Software

11. My Natural Radio Spectrum Set-up
Antenna
Soundcard

12. 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

13. 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

14. VLF receivers currently monitored

15. 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
W/m2 M
W/m2 C
W/m2 B
W/m2 A
W/m2
Increasing Energy
A text book SID
Importance = 2+
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+

16. 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

17. SID

18. Raw Data can be a little confusing

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

20. SIDs come in many shapes

21. Results

22. 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

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