RADIO ASTRONOMY FOR AMATEURS
Paul HydeBAA Radio Astronomy Group([email protected])
Norfolk Amateur Radio Club2016 September 14
Po
wer
Flu
x D
en
sit
y (W
m-2
Hz
-1)
10-15
Broadcast signals
10-17
10-19
10-21
10-23
10-25
Supernova remnants
Radio galaxies
Pulsars
Communications Receiver
Courtesy Dr David Morgan
A million times weaker still!
10-13
Reference level
10,000 x sensitivity
Radio signals are weak
Background noise is high
To observe a source, we have to be able to distinguish it from the background noise, i.e. achieve a reasonable Signal to Noise Ratio
What can amateurs observe
1. Use INDIRECT observations
Look at the effects of an event, not the event itself
a) Sudden Ionospheric Disturbances (SIDs)
b) Meteor Scatter
2. Look at sources closer to home
a) Jupiter – Io emissions
b) Solar radio bursts
3. More advanced applications
a) Hydrogen Line reception
b) Interferometry
Sudden Ionospheric Disturbances
Very Low Frequency (VLF) radio signals (15 – 25 kHz) are guided between the conducting ground and the ionosphere
The ionosphere responds quickly to changes in solar X-ray and UV emissions associated with flares
Sudden Ionospheric Disturbances
Sunrise Sunset
Red trace 19.6 kHz Anthorn, CumbriaGreen trace 20.9 kHz St Assise, FranceBlue trace 22.1 kHz Skelton, Cumbria
Radio SkyPipe software
Sudden Ionospheric Disturbances
Zotac Z-box mini pc
Antenna
(multicore cable with cores daisy-chained together)
VLF Receiving SystemMark Edwards, Coventry
Connected to MIC input of a PC
Sudden Ionospheric Disturbances
Spectrum Lab software
Approx 2 hours
X-class event observed by Mark EdwardsCoventry
www.qsl.net/dl4yhf/spectra1.html
Meteor Scatter
24-hour visibility – day or night, in cloud or sunshine, with moon or light pollution
NASA
GRAVES Space Surveillance Radar
High power radar system located near to Dijon, France
Transmit frequency 143.05 MHz
Four antenna arrays producing individual beams stepping across the sky
Meteor Scatter
Rapidly moving meteor 'head'
500 Hz change in frequency is equivalent to 1,000 m/s change in Line of Sight (LOS) velocity
Radio source is GRAVES Space Radar at 143 MHz
10 secs
Frequency =
LOS velocity
Meteor Scatter
Extended plasma trail lasting tens of seconds(time is proportional to mass)
Shows 'beam switching' at GRAVES transmitter
FUNcube Dongle Software Defined Radio
Developed to receive the FUNcube-1 satellite
Expected to sell about 50 units but has sold > 10,000
£150 including p&p
Can also be used to receive:
Weather satellites & meteorological balloons
Hydrogen Line
Jupiter emissions
Meteor Scatter
Encouraging participation
“How to …” article in June and July 2014 editions
Positive feedback from Sky at Night editorial team
Further article requested for later this year
Articles available for download from the BAA RAG website www.britastro.org/radio/
Still talking £200 for a complete installation
Meteor Scatter
Interesting detail in the trail as it splits into different layers moving at different velocities (frequencies)
10
15
20
25
30
35
40
45 90 135 180 225
E
l
e
v
a
t
i
o
n
Azimuth
Moon position for EME
13-Jul
22-Jun
20-Jun
19-Jun
18-Jun
17-Jun
16-Jun
Moonbounce
Indicative of power of the GRAVES radar system
Position of Moon when moonbounce signals seen
Moonbounce signal
Spectrum Lab software
Freeware audio analysis software
Displays 'pings'
Automated save of .jpg images and .wav sound files
Logs time, duration, intensity, frequency
Data can be uploaded to a comparison site
Meteor Scatter
What can amateurs observe
1. Use INDIRECT observations
Look at the effects of an event, not the event itself
a) Sudden Ionospheric Disturbances (SIDs)
b) Meteor Scatter
2. Look at sources closer to home
a) Jupiter – Io emissions
b) Solar radio bursts
3. More advanced applications
a) Hydrogen Line reception
b) Interferometry
Jupiter Emissions
NASA's 'Radio Jove' antenna and kit receiver
Jupiter emissions can be picked up with an ordinarycommunications receiver at around 20 MHz
Solar radio bursts
Laptop with Terminal Emulator and FITS file reader
Outdoor antenna(3 ele wire Yagi)
R75 Receiver and PIC-based Controller
Solar radio bursts37.50
38.25
MHz
UTC0700 0900 1100 1300 1500
Narrowband terrestrial interferers
Broadband terrestrial interferers
?
Solar radio bursts
37.50
38.25
MHz
Space Weather Prediction Center report:
0942 0949 RSP 025-180 V/3 ?Start End Sweep-
frequency
Radio
Burst
Type V burst
Intensity = Major
Enlarged detail
Solar radio bursts
e-CALLISTO receiver from ETH Zürich
Scans 45 - 870 MHz using a cable-TV tuner
30 units deployed across professional observatories around the world
Courtesy ETH Zurich
Advanced stuff ...
'Weak signal' work is possible for the serious amateur:
1. Total Power instruments
Use a single antenna to obtain direct measurements of source- Hydrogen Line at 1421 MHz- Broadband Black Body- Synchrotron radiation
Brian Coleman’s Redenham Observatory
http://myweb.tiscali.co.uk/g4nns/radast.html
Hydrogen Line
Charts courtesy of John McKay3 Peaks Observatory
Galactic Longitude 180°
Galactic Longitude 70°
Galactic Longitude 220°
Rest frequency = 1,420 MHz
www.3peaks.org.uk/
Hydrogen Line
David Morgan's Monmouth Observatory
Hydrogen Line Observing Group
Doppler Shift Intensity
www.dmradas.co.uk/http://myweb.tiscali.co.uk/g4nns/HLOG.html
Hydrogen Line
Peter East’s £200 H-LineTelescope
• 4 off 22-ele Yagis
• £15 Budget TV Dongle
http://y1pwe.co.uk/RAProgs/
index.html
Raspberry PiSingle Board Computer
Future opportunities
Consumer electronicsfront-ends
£15
£30
£20 £5
Raspberry PiSingle Board ComputerConsumer
electronicsfront-ends
… with software defining the instrument
Meteor scatter Hydrogen Line Jupiter Solar radio bursts
SID receiver
Future opportunities
InterferometryAdd signals from two widely spaced antennas- Much higher resolution than single antenna- Ability to distinguish between small sources
and background noise
30 metres
West arm East arm
www.dmradas.co.uk/
Interferometry
Virgo A = M87
Giant elliptical galaxy with a supermassive Black Hole at the core
Distance = 53.5 million light years
www.dmradas.co.uk/
Conclusions
There are applications which are relatively straight forward and suitable for non-radio experts
Man-made interference is an increasing problem – we need to find radio-quiet sites
The more dedicated amateur can observe 'deep-sky' radio objects: Hydrogen Line, Radio Galaxies, Supernova remnants
A possible way forward is collaboration between Astronomical Societies, Amateur Radio Clubs and software 'hackers'
Resources
TutorialsBasics of Radio AstronomyExcellent introduction to the concepts that lie at the heart of radio astronomy
Radio Astronomy TutorialsMore advanced tutorials from MIT Haystack observatory.
NJIT Course notes by Prof. Dale E. GaryAnother advanced series of lectures covering all aspects of radio astronomy
See www.britastro.org/radio/
ByJeff Lashley
By John Fielding
Burlington HousePiccadillyLondon
W1J 0DU
(+44) 207 734 4145 [email protected]
Registered Charity No. 210769
British Astronomical AssociationRadio Astronomy Group