Monitoring Solar flares by Radio Astronomy Presented at the RASC Sunshine Coast Centre, February 8th, 2013, 7:30 pm Mike Bradley, RASC Sunshine Coast Centre
Solar flares Solar flares occur when sunspots with very complex magnetic fields become unstable and start to untangle themselves. This process releases very large quantities of energy. Unstable sunspot group The X-ray and UV energy released by these solar flares makes its way to Earth and interacts with the upper atmosphere to create a SID.
Ionospheric Layers
Ionospheric Layers Topside From F2 layer to 500/1000km transition O+ less than H+ & He+ F Layer Above 150km, reflecting F2 layer, ions NO+ to O+ E ELayer 95 150km, ions are mainly O++, also thick E2, thin sporadic E D Layer 75 95km, weak ionisation, absorbs HF
Understanding the ionospheric response When the X-ray and UV energy reaches the upper levels of our atmosphere it rapidly increases the ionisation levels of the ionosphere levels that are responsible for refracting terrestrial radio signals. Terrestrial radio signals at very low frequencies (below 30kHz) propagate as guided d waves between the earths surface and the D layer. They can also penetrate seawater to about 10m. During a solar flare the ionisation of the layer increases dramatically and its height rapidly reduces. After the flare, through recombination, its ionisation gradually returns to normal and the layer gradually rises to its original level.
Sudden Ionospheric Disturbance (SID) A sudden ionospheric disturbance is an abnormally high ionization/plasma density in the D region of the ionosphere caused by a solar flare. The SID results in a sudden increase in radio-wave absorption that is most severe in the upper medium frequency (MF) and lower high frequency (HF) ranges, and as a result often interrupts or interferes with telecommunications systems. * * Federal Standard 1037C, Glossary of Telecommunications Terms
Quiet Sun Very Low Frequency (VLF) radio signals (3...30kHz) are guided between the conducting ground and the D-layer. The D-layer is a region of the ionosphere that is ionised directly by solar radiation. It is present only during the day, and responds quickly to changes in solar radiation.
Night time At night, solar radiation cannot ionise the D-layer. Very Low Frequency radio signals cannot propagate efficiently. The E-layer is responsible s e for reflecting ect higher frequency radio signals, which often rise in strength at night.
Active sun Solar flares produce UV and X-rays, increasing the ionisation (electron density) of the D-layer. The Sudden Ionospheric Disturbances (SIDs) alter VLF propagation, producing rapid and distinctive changes in received signal strength.
Very Low Frequency (VLF) radio The VLF signals we are interested are the submarine signals used by all countries with naval submarines. Typically 3-30 30 khz. VLF wavelength penetrate a short distance into seawater so subs don t need to surface to communicate. Monitoring i these signals is legal, l the coded d information content is of no interest, it s only the signal strength th we monitor.
Jim Creek, WA, US Navy transmitter
About 24.8 khz Amplitude (Peak-to-Peak) Radio Signal 11 Cycle = 12 km Distance traveled over time How to make this Computation? Speed of light: c = 300,000 km/sec Frequency: f = 24,800 Cycles/Sec Wave Length: λ = c / f km / Cycle
The VLF signals I monitor Jim Creek WA La Moure ND Jim Creek is so close (150 km) that the ground wave signal dominates. La Moure gives better results (2500 km)
Detecting the signal The frequencies we are trying to monitor are similar wavelengths to audio waves, but they are electrical, not sound pressure waves. A microphone converts sound pressure variations into electrical signals. An antenna converts electrical waves into electrical signals. Simply connecting an antenna to the soundcard of a computer is the simplest way to digitise and capture the signals we want. Even on cloudy days, from your basement!
Detecting the signal Alternatively a dedicated very low frequency (VLF) receiver can be used Several designs, most not too difficult to build Amateur and Educational commercial units available
Continuously recording the signal Save the output from the PC soundcard as a file, analogue or digital. or Capture the average signal strength as a voltage on a chart recorder or an analogue to digital converter Observe and analyse
Flat file structure UTC 24800 25000 25200 00.00.01 95.52 112.59 112.26 00.00.21 95.66 112.79 112.28 00.00.41 95.7 7 112.83 112.33 00.01.01 95.76 113.03 112.19 00.01.21 95.9 113.07 112.28 00.01.41 95.97 113.25 112.37 23.59.01 97.75 113.73 114.14 23.59.21 21 97.75 75 113.91 114.29 23.59.41 97.64 114.15 114.95
Software Spectrum Lab is a full featured audio analysis program, it performs frequency analysis and spectrum sampling, ideal for SID. It is also free. The frequency analysis is done using the Fast Fourier Transform rather than discrete filters and therefore the Nyquist sampling limit apply This means the PC soundcard must be able to sample at a minimum of twice the highest frequency being observed i.e. 25.2kHz 2kH -> 50.4 khz -> 96kHz
Spectrum Lab Audio spectrum screen Audio spectrum Waterfall chart
Spectrum Lab FFT detail Jim Creek WA 24.8 khz La Moure ND 25.5 khz Unknown, Russian Federation 25.0 khz Spectrum Lab can be configured to save the values of these peaks to a simple text file or to simply draw a chart.
Normal 24 Hr. Day (No flares) 3 2.5 2 Local Noon 1.5 1 0.5 0 05:27: 06:03: 06:38: 07:00: 07:35: 08:10: 08:46: 09:21: 09:57: 10:32: 11:08: 11:43: 12:19: 12:54: 13:30: 14:05: 14:41: 15:16: 15:52: 16:27: 17:03: 17:38: 18:13: 18:49: 19:24: 20:00: 20:35: 21:11: 21:46: 22:22: 22:57: 23:33: 00:08: 00:44: 01:19: 01:55: 02:30: 03:05: 03:41: 04:16: 04:52: 50 18 46 03 31 59 27 56 24 52 20 48 16 44 12 40 08 36 04 32 00 28 56 24 53 21 49 17 45 13 41 09 37 05 33 01 29 57 25 53 21 Nighttime Sunrise Daytime Time in UT Sunset Nighttime
5 4.5 4 3.5 3 2.5 2 Detecting Solar Flares SID(s) () SID Events! Local Nighttime Sunrise Daytime Local Nighttime 07:00:03 07:31:26 08:02:48 08:34:11 09:05:34 09:36:56 10:08:19 10:39:42 11:11:05 11:42:27 12:13:50 12:45:13 13:16:35 13:47:58 14:19:21 14:50:44 15:22:06 15:53:29 16:24:52 16:56:14 17:27:37 17:59:00 18:30:23 19:01:45 19:33:08 20:04:31 20:35:53 21:07:16 21:38:39 22:10:01 22:41:24 23:12:47 23:44:10 00:15:32 00:46:55 01:18:18 01:49:40 02:21:03 02:52:26 03:23:49 03:55:11 04:26:34 04:57:57 05:29:19 06:00:42 06:32:05 However, not all SID events are explainable. Research is needed to help answer What are these events?
Connecting SID to GOES X-ray satellite data 5 4.5 C4.5 C5.9 9 C3.8 M1.3 4 3.5 3 2.5 2 Local Nighttime Sunrise Daytime Local Nighttime 07:00:03 07:31:26 08:02:48 08:34:11 09:05:34 09:36:56 10:08:19 10:39:42 11:11:05 11:42:27 12:13:50 12:45:13 13:16:35 13:47:58 14:19:21 14:50:44 15:22:06 15:53:29 16:24:52 16:56:14 17:27:37 17:59:00 18:30:23 19:01:45 19:33:08 20:04:31 20:35:53 21:07:16 21:38:39 22:10:01 22:41:24 23:12:47 23:44:10 00:15:32 00:46:55 01:18:18 01:49:40 02:21:03 02:52:26 03:23:49 03:55:11 04:26:34 04:57:57 05:29:19 06:00:42 06:32:05
Flare Classifications Class Energy 6 X 10-4..10-3 W/m 2 5 M 10-5..10-4 W/m 2 3 C 10-6..10-5 W/m 2 2 B 10-7..10-6 W/m 2 1 0 A 10-8..10-7 W/m 2 4 A B C M X Logarithmic scale, each class can be further divided by 10, ie C 5.6 or M1.5 Typical quiet sun produces energy in the A or B class, Most flares fall into theborcclass class. VeryenergeticflaresareMorXclass energetic class. Extremely energetic flares can exceed X9.9, ie X20!!!
Solar activity varies from day to day Animation courtesy Moore Observatory, Kentucky
Nov 13 th from Roberts Creek -90-95 -100-105 -110-115 -120 00.00.01 00.28.21 00.56.41 01.25.01 01.53.21 02.21.41 02.50.01 03.18.21 03.46.41 04.15.01 04.43.21 05.11.41 05.40.01 06.08.20 06.36.40 07.05.00 07.33.20 08.01.40 08.30.00 08.58.20 09.26.40 09.55.00 10.23.20 10.51.40 11.20.00 11.48.20 12.16.40 12.45.00 13.13.20 13.41.40 14.10.00 14.38.20 15.06.40 15.35.00 16.03.20 16.31.40 17.00.00 17.28.20 17.56.41 18.25.01 18.53.21 19.21.41 19.50.01 20.18.21 20.46.41 21.15.01 21.43.21 22.11.41 22.40.01 23.08.21 23.36.41 UTC
Nov 13 th from Roberts Creek -105 NML VLF (N.Dakota) X Class flare 6.1e-3, Event 2410-106 db -107-108 21.54.01 21.56.21 21.58.41 22.01.01 22.03.21 22.05.41 22.08.01 20.32.21 20.34.41 20.37.01 20.39.21 20.41.41 20.44.01 20.46.21 20.48.41 20.51.01 20.53.21 20.55.41 20.58.01 21.00.21 21.02.41 21.05.01 21.07.21 21.09.41 21.12.01 21.14.21 21.16.41 21.19.01 21.21.21 21.23.41 21.26.01 21.28.21 21.30.41 21.33.01 21.35.21 21.37.41 21.40.01 21.42.21 21.44.41 21.47.01 21.49.21 21.5 1.41 UTC
Sunspot AR1613, Event 2410 Solar image courtesy HeliumFusion channel, YouTube
Conclusions Strictly speaking this is not a radio telescope. We are not detecting radio waves directly from space. Instead we are detecting the effect of solar activity indirectly, so it is certainly radio astronomy! A A simple, low cost, interesting ti project for a rainy afternoon
A proper Radio Telescope! Dominion Radio Astrophysical Observatory (DRAO) at White Lake in the Okanagan. The area is federally protected from radio interference.
Thank you for your attention!
Questions?
Tuning the Antenna (not essential) 25.2kHz