Intro to Amateur Radio Astronomy
Nathan Butts – KQ4TIV
Wannabe Astronomer
SOKY-RAD
Licensed under GNU GPL 3.0
Abstract
My name is Nathaniel Butts, KQ4TIV, and I am a 2009 graduate of WKU in Mechanical Engineering. I have loved astronomy since my earliest days, and studied astronomy at WKU for a brief time, where I was introduced to Radio Astronomy.
This is intended to be a short introduction to Radio Astronomy is, the basic mechanisms of the Physics, example projects, and an example of projects I am currently working on.
Licensed under GNU GPL 3.0
Radio Wave Basics
Radio waves are photons of electromagnetic radiation generated by charged particles undergoing acceleration.
This acceleration can be caused by time-varying electric currents (the radio that may or may not still be in your car), close to magnetically dense objects like large planets, stars, spinning black holes, or galaxies, or from natural quantum processes.
Licensed under GNU GPL 3.0
Where do these waves come from?
Licensed under GNU GPL 3.0
Magnetosphere of Jupiter. Trapped particles from volcanic activity of Io is often accelerated to magnetic poles, creating waves.
Supermassive black holes. The Milky Way black hole in Sagittarius A was the first radio object discovered in space, in 1932 by Karl Jansky.
Random quantum mechanical processes like spin-flip photon emissions of neutral Hydrogen caused when electron and proton spins become parallel.
Others:
- Pulsars caused by neutron stars emitting synchrotron radiation
- Fast radio bursts – source currently unknown
- Star forming regions
- Cosmic microwave background radiation – remnants of Big Bang
- ET - maybe
Radio Spectrum
Licensed under GNU GPL 3.0
Credit: NASA https://www.nasa.gov/directorates/somd/space-communications-navigation-program/radio-vs-optical-spectrum/
The radio spectrum covers a wide part of the electromagnetic spectrum; about the same amount as infrared, visible, ultraviolet, X-ray, and Gamma-Ray combined.
Because of the properties of our atmosphere, a large part of spectrum is blocked (thankfully in some cases) from the earth’s surface. Radio waves are detectable through our atmosphere from approximately 20MHz to 14GHz.
By NASA (original); SVG by Mysid. - Vectorized by User:Mysid in Inkscape, original NASA image from File:Atmospheric electromagnetic transmittance or opacity.jpg., Public Domain, https://commons.wikimedia.org/w/index.php?curid=5577513
Why Radio vs. Visual
Why Radio Astronomy at All?
My Projects
Licensed under GNU GPL 3.0
Equipment
Licensed under GNU GPL 3.0
Waveguide
Neutral Hydrogen
Waveguide
Licensed under GNU GPL 3.0
Open End
¼ λ
Processing Data
Half the battle is getting the signal, the real science starts with spectroscopy.
Radio emissions from space objects are very weak, and creating spectroscopy data from these signals would be impossible without this handy formula:
Called the Fast Fourier Transform, this is used to break down a signal into its constituent cosine waves. Thank you Mr. Laplace!
Watch these videos if you really want to nerd out on the math:
Licensed under GNU GPL 3.0
Map of Galactic H1 in RaDec
Licensed under GNU GPL 3.0
Not the cleanest scan data. I thought I had the striations eliminated (originally caused by a change in waveguide construction) but it is still present. However, you can see the galactic hydrogen and how it compares with professional plots
Will work in future to process find my missing data (I know it’s there), and still clean up the striations.
Map of Galactic H1 in Mercator
Licensed under GNU GPL 3.0
Same data, plotted in Mercator projection. Data shows more pronounced difference between lower and highest values.
This is taking the RaDec values and modifying the projection so the galactic arms are more in-line.
Areas in white are not viewable from my position on Earth.
12/5-ran ezSky again, but masking areas without data.
Possible Galactic Hydrogen
Licensed under GNU GPL 3.0
Scutum-Centaurus Arm
Perseus Arm
Sagittarius Arm
(not viewable)
Outer Arm
This shows possible detected Hydrogen, plotted at distances from galactic center. Essentially an “overhead” view. Black area is not accessible from my location (Northern Hemisphere).
12/5-updated arrows to correct arms
Possible Galactic Hydrogen
Licensed under GNU GPL 3.0
Overlaid ezGal580galArmsGC.png plot over NASA/JPL artwork.
For such rough data, it lines up really well.
Interpolated Velocity
Licensed under GNU GPL 3.0
Galactic longitude view of the galaxy, with longitude across x axis.
This tends to show that material in Q2 is the Perseus Arm moving slower relative to our position. Q1 material in Perseus Arm possibly the Scutum-Centaurus Arm is moving at same speed or slightly faster than our relative position. Q3 shows material moving faster away from our relative position in the tail of Perseus.
12/5-removed spurious image and added description on relative velocities.
Professional Data
Velocity at Galactic Longitude
Licensed under GNU GPL 3.0
Looks like an album cover I remember…..
The removal of top and bottom 5% of data in the processing portion created some distinct cut off lines.
However, it does show the change in spectrum nicely, but without the detail I would prefer.
Comparing these with larger telescope data show me the limitations of this method.
Measured Gas Velocity
Licensed under GNU GPL 3.0
After mild cleanup, got it to 106% (started at 151% originally) of the value provided by Kafle, Sharma, Lewis, Bland-Hawthon in “Kinematics of the Stellar Halo and the Mass Distribution of the Milky Way Using Blue Horizontal Branch Stars.”
Ran with arguments:
-ezGalVelGLonEdgeLevelL 1.03 40 140
Measured Mass of Galactic H1
Licensed under GNU GPL 3.0
After some cleanup, it changed 1.84e+11 to 1.12e+11, now within 3%.
Dr. Angela Collier, "Dark matter is not a theory, it's a list of observations showing missing mass."
Other Projects
Licensed under GNU GPL 3.0
ScintPi with University of Texas Dallas
Low cost ionospheric scintillation and total electron content
Part of the University of Texas Dallas Upper Atmosphere Research Program. https://labs.utdallas.edu/rodrigues/
Using GPS constellations and a GNSS receiver, measuring the changes in scintillation and total electron count from these satellites to measure the thickness and changes in the Ionosphere.
Other Projects
Licensed under GNU GPL 3.0
Sudden Ionospheric Disturbances – measuring affects of geomagnetic storms on ionosphere
Sudden Ionospheric Disturbances (SIDs) are sudden increases in the opaqueness of the D, E, and F layers of the ionosphere caused by electromagnet radiation generated from solar flares. By monitoring VLF stations used to send communications to submarines, you can measure the changes in the signal strengths of these stations and calculate the intensity of the solar flare with high precision.
Thank you!
Thank you for making it this far.
Questions?
Licensed under GNU GPL 3.0
Appendix
Licensed under GNU GPL 3.0
Dimensions
Horn
Waveguide
Licensed under GNU GPL 3.0
Software
Licensed under GNU GPL 3.0
ezRA - Easy Radio Astronomy
Free 1420 MHz Galactic hydrogen data collection and analysis
https://github.com/tedcline/ezRA
Windows and Linux
Examples of projects with costs
Super SID
Scope in a Box
SOKYRAD Pyrmid Horn
Why Radio Astronomy at All?
dspira
Sdr#
Velocity at Galactic Longitude
Quadrant 1
Quadrant 2
Licensed under GNU GPL 3.0
Velocity at Galactic Longitude
Quadrant 3
Quadrant 4
Licensed under GNU GPL 3.0
Measured Mass of Galactic H1
Licensed under GNU GPL 3.0
My measured value of 1.84x10^11 is within 16% of the value provided by Kafle, Sharma, Lewis, Bland-Hawthon in “Kinematics of the Stellar Halo and the Mass Distribution of the Milky Way Using Blue Horizontal Branch Stars.”
Not great, but it does not follow Keplarian motion, meaning this is further observational evidence of missing visible mass from the galaxy.
Dr. Angela Collier, "Dark matter is not a theory, it's a list of observations showing missing mass."