Willowbank Observatory

located at Pennyghael on the Isle of Mull

56°22'45N  6°00'07"W


Weather Instruments

The weather station is a Davis Vantage Pro 2 weather station. The anemometer and wind vane are mounted on a short mast attached to a chimney about 5 m agl. The USB webcam is a Logitech 9000 Pro, using 1600x1200 resolution . The webcam and all website uploads are handled by a Raspberry Pi 2. A RPi model A is used as a local NTP server for all systems.

I use WeatherDisplay software, which allows the weather web pages to be automatically generated.

Both the weather station, associated PCs, and the SAM magnetometer have mains supplies via UPS; in the event of a protracted supply outage then everything with the exception of the SAM instrument is shut down. The SAM system is kept powered for as long as possible, using a seperate battery to keep the sensors stable.


SAM: Simple Auroral Magnetometer

The Northern Lights (or Aurora) are a stunningly beautiful, and moderately rare natural phenomena. They are ultimately driven by events on the Sun, the frequency and severity of which vary over an approximately eleven year cycle. These solar disturbances can interact with the Earth's magnetic field as part of the process which produces auroral displays. Thus monitoring small changes in the field can help to predict auroral activity. This is of interest to radio amateurs as such events are often accompanied by HF radio propagation disturbances, and enhanced VHF propagation is possible by using the aurora as a reflector.

Some good hints on predicting the probability of a visual aurora at your own location can be found at this NASA site.

The SAM magnetometer was designed by Karsten Hansky, DL3HRT and Dirk Langenbach, DG3DA and was described in DUBUS magazine issue 2/03. It can measure small changes in one, two or all three components of the Earth's field, using fluxgate sensors that are made by Speake. For more details, see the SAM website and the SAM International website. These contain both construction information, details of kits and access to real-time data from a number of stations across Europe and the world.

The installation at Willowbank now uses three sensors, one for the vertical component (Hz), one for the E-W component (Hy) and one for the N-S component (Hx), arranged at right anles to each other. My SAM magnetometer has been modified to accept a third sensor. The magnetometer software records changes from the midnight value, in units of nanoTesla (nT) for each axis. The resulting graph is uploaded every 15 minutes. On the graph you will see a series of K values, such as K=3. This is a measure of magnetic disturbance. A knowledge of the local K value, together with your magnetic latitude, can be used to judge the likelhood of an auroral display, as the link above describes. Because the fluxgate sensors used are sensitive to temperature, they are buried some 1.7 m below ground. They are about 65 m from the house and 80 m from the road, so the effects of (the occasional) passing traffic are negligable. Records are archived and stored, so if you are interested in the magnetic records for any day since December 2006, they are easily available, just contact me via the e-mail link below.

My modifications to the SAM Magnetometer design, made to improve the performance with long cables are described here.


Sudden Ionospheric Disturbance (SID) Recorders

Solar (X-ray) flares, amongst other events, can cause changes in the ionosphere which result in enhanced received signal strengths during daylight hours at low frequencies (up to 100 kHz or so). The SID monitoring systems record the received signal strength of LF transmitters.

The single channel system is a dedicated Gyrator II receiver, with an active E-field antenna (details here). The receiver output is passed to a Labjack U3-HV A/D converter and laptop running RadioSkypipeII software. A User Data Source (UDS) written in Visual Basic allows data from the Cosmic Watch instruments (see below) to be graphed as well.

The multi-channel receiver uses the same active antenna connected to a EE-MU 0202 USB soundcard and Raspberry Pi4. This runs Paul Nicholson's VLF tools, producing individual plots for each VLF station of interest, updated every 15 minutes.
Currently under development.

Images of the charts are automatically uploaded to this site using a Raspberry Pi, which also controls the webcam. A dedicated Raspberry Pi is used as a local NTP server for all instrumernts.


Muon Counter Experiment

This experiment uses two UKRAA 'Cosmic Watch' solid-state scintillation detectors which are located one above the other. They have been slightly modified to allow pulses for total master (background) and coincidence (muon) counts to be fed to two counter channels on the LabJack U3-HV. The idea is to detect muons from cosmic rays. Although only 30 minute rolling averages are displayed for both counter channels, the data is collected and recorded in counts in 1 minute bins. More details to follow soon.

More information on the Cosmic Watch project can be found here.


Past data is freely available, email me at the address below.  
Comments, or suggestions for changes, are welcome.  

Please send them to me at : marsport@marsport.org.uk

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