One talk by Alex Pettit describes how to build a radio telescope from a an umbrella and some "Faraday fabric" which is copper cloth. The results show more than adequate performance for the cost, making this an affordable and easy entry to radio astronomy.
Alex Pettit - Umbrella Antennas
Another video presented by Dr. Wolfgang describes building small to medium sized radio telescopes. He explains how small radio telescopes less than 3 meters in size can work well for receiving the 21cm Hydrogen line, and how SDRs are the best choice of receiver for them. Many examples of small dish installations are shown.
Dr. Wolfgang Herrmann: Building Small/Medium Size Radio Telescopes
Back in January 2020 we posted a tutorial showing how it's possible to detect and measure the galactic Hydrogen line using a simple 2.4 GHz WiFi dish, RTL-SDR Blog V3 and a filtered LNA. Since then many people have used the same setup with great results.
Over on YouTube user stoppi who is one such person who is using the same steps from our tutorial, and he has uploaded a video showing his setup and results. If you're thinking of getting started with Hydrogen Line reception, his video slide show tutorial would be a good complimentary overview to go along with our text tutorial.
Detection of the galactic hydrogen - the 21 cm radiation - Wasserstoffstrahlung der Milchstrasse
In his most recent work Job has managed to detect the W3 star forming region at the Hydroxyl (OH) frequency of 1665.405 MHz.
W3 is an enormous stellar nursery about 6200 light-years away in the Perseus Arm, one of the Milky Way galaxy's main spiral arms, that hosts both low- and high-mass star formation. - Source
Hydroxyl (OH) can be observed both in emission and absorption. Emission frequently manifests itself as maser emission which is of specific interest. Energy Levels of OH Diatomic molecules like OH have numerous energy levels as they not only have electronically excited levels, but they can also vibrate and rotate. Both rotation and vibration are quantized and give rise to the large number of levels. Because of the wealth of energy levels, OH can be observed at various wavelength in the optical, infrared and radio regime. - Source
Over on the RTL-SDR Facebook group (not affiliated with this blog), Job has described his experiment in more detail (link requires a Facebook account and membership). He writes:
As you may know or not...., I have been busy the last few weeks trying to detect maser W3(OH) with my 1.5-1.9 dish. The W3 complex lies in a darkened part of the Perseus galactic arm, at a distance of ∼2.2 kpc, and is one of the most intensively studied star-forming regions in the Milky Way Galaxy. Quite a challenge! It looks like I have a hit now after all.
Adjusting the Feed, calibrating the position of the dish and a lot of trial and error and a lot of patience seem to be leading to a result after all.... For now, I will keep this as my W3(OH) registration at 1665.405 MHz. Taking into account the Vlsr of currently 17 km/s (speed of earth and rotation around the sun), the final result comes close to the correct measurement. 1665.789 MHz = -32.22 km/s. Vlsr according to my calculations in terms of location and time is 17 km/s. -32-17=49 km/s. I think and hope that -49 km/s is the correct velocity of W3(OH) also considering the reasonably clear peak in the measured values in the graph.
These W3(OH) results were done with a special 1665 bandpass filter and 2 mini circuits lna/s. I will keep measuring for a while in the coming days, but soon I will switch back to another Feed over, namely the now under construction 611 MHz Feed with associated bandpass filter to once again 'capture' pulsar B0329+54. My ultimate goal with this dish!
I was very close last six months, but after extensive research with fellow radio amateurs we unfortunately could not confirm with 100% (!) certainty that the pulsar was detected at 1420 MHz with the 1.9 dish.
Also that research continues with longer exposure times and now research at 611 MHz, there is still some soldering and drilling and sawing to be done..... But first things first. Glad with this result anyway. Takes a lot of perseverance and patience.
Job's Radio Telescope detects Maser W3(OH).Job's Radio Telescope detects Maser W3(OH).
During September 26 - 30 GNU Radio Conference 2022 was held in Washington DC. GNU Radio Conference (aka GRCon) is an annual conference centered around the GNU Radio Project and community, and is one of the premier software defined radio industry events. GNU Radio is an open source digital signals processing (DSP) tool which is used often with SDRs.
A few days ago videos of all the presentations were released on their YouTube channels, and all the talks can be found on this playlist. The videos contain a mix of in person and remote talks. A schedule of all talks can be found on the GNU Radio website.
NASA's Radio Jove is a project that enables students and amateur scientists from around the world to observe and analyze the HF radio emissions from Jupiter, our Sun and our galaxy using easy to construct HF radio telescopes that receive spectrographs from 16-24 MHz. The project has existed for more than two decades, and these days the telescope builds mostly make use of low cost software defined radios.
In a presentation for the Society of Amateur Radio Astronomers (SARA) Richard Flagg & Jim Sky talk about what sort of hardware is used these days for the Radio Jove project. They note that SDRs like the Softrock, Funcube Dongle Pro+, SDR-IQ, SDR-14, RTL-SDR, and RASDR have been used. They go on to discuss some of the spectrograph logging software that is used with the project as well.
The presentation slides in PDF form can be found here.
Richard Flagg & Jim Sky: Radio Jove Spectrograph Hardware and Software (RJ10/11)
Over on YouTube the Society of Amateur Radio Astronomers have recently uploaded talks from their SARA 2022 online conference. Two of the talks we've seen focus on describing results produced by small and cheap WiFi Grid RTL-SDR radio telescopes.
Back in early 2020 we first published an article about how it is possible to use get into amateur radio astronomy cheaply using off the shelf WiFi grid dishes, combined with a 1420 MHz LNA + filter, an RTL-SDR and the SDR# software with IF average plugin to measure the galactic hydrogen line.
In the SARA conference we've seen two talks expanding on the use of WiFi grids for radio astronomy. In the first talk Alex Pettit discusses how he's used a WiFi grid attached to an equatorial telescope mount, and a custom modified feed in his setup. In his talk he explains how to use the IF average plugin, and how he uses a MATLAB script to process and plot the saved data.
Alex Pettit: Galactic Hydrogen 1.42 GHz RF Emission Radio Astronomy for $300
In the second talk Charles Osborne describes his "Scope-In-A-Box" which consists of the WiFi Grid, LNA, Filter and RTL-SDR combination and compare the setup versus the same hardware used on a larger 3.7m dish.
Charles Osborne: Comparing Scope-in-A-Box to a 3.7m Dish
If you were interested in those talks, you might also want to check out the other talks from the conference, many of which also involve the use of software defined radios in the receive chain for various amateur radio astronomy experiments.
Job's latest work has seen him detect Pulsar B0329+54 with his 1.9m dish and an RTL-SDR. He writes:
A pulsar is the rapidly spinning and pulsating remnant of an exploded star.
PSR B0329+54 is a pulsar approximately 3,460 light-years away in the constellation of Camelopardalis. It completes one rotation every 0.71452 seconds and is approximately 5 million years old
Everything indicates that I may have been able to detect the pulsar B0329+54 with JRT [Job's Radio Telescope]. This dish has a diameter of 1.9 meters, which would make it the first time (!) this pulsar has been detected with a dish of this size as far as I can tell. This result was obtained thanks to the good help and software of Michiel Klaassen.
Job has also provided a PDF file that documents his setup and results in more detail, which we have uploaded to our server here.
Over on Facebook Job Geheniau has recently described his success in detecting interstellar high-velocity clouds with his telescope consisting of a 1.8 meter dish, amplifiers, band pass filters, and an RTL-SDR.
High-velocity clouds or HVC's are areas of interstellar gas that are moving at very high velocities relative to that of the galactic rotation.
His latest post about detecting high velocity clouds reads:
CIII High Velocity Cloud detected with 1.8 meter JRT.
The receiver was a RTLSDR connected to some amplifiers, band pass filter and a 1.8 meter dish.
HIGH VELOCITY CLOUD CIII with JRT (Job’s Radio Telescope)
Wikipedia: “High-velocity clouds (HVCs) are large collections of gas found throughout the galactic halo of the Milky Way. These clouds of gas can be massive in size, some on the order of millions of times the mass of the Sun and cover large portions of the sky. They have been observed in the Milky Way's halo and within other nearby galaxies.
HVCs are important to the understanding of galactic evolution because they account for a large amount of baryonic matter in the galactic halo. In addition, as these clouds fall into the disk of the galaxy, they add material that can form stars in addition to the dilute star forming material already present in the disk. This new material aids in maintaining the star formation rate (SFR) of the galaxy.
The origins of the HVCs are still in question. No one theory explains all of the HVCs in the galaxy. However, it is known that some HVCs are probably spawned by interactions between the Milky Way and satellite galaxies, such as the Large and Small Magellanic Clouds (LMC and SMC, respectively) which produce a well-known complex of HVCs called the Magellanic Stream. Because of the various possible mechanisms that could potentially produce HVCs, there are still many questions surrounding HVCs for researchers to study.”
My detection:
For JRT the High Velocity Clouds are pretty hard to detect.
The Anti Center Complex is the easiest which I detected earlier last year.
This week I tried C III. It’s at Galactic Coordinates 120 50 and has a Vlsr of -140 km/s. You can find it on the chart:
In the simulation it looks like this:
Pay attention the low Brightness Temperature (0.3 Kelvin) compared for instance with Deneb (80 Kelvin)! Pretty hard to detect with my dish.
With JRT I did a 4 hour exposure (also 4 hours of Darks in the neighborhood) at 1420.405 MHz.
The new Feed I built is very good and has a perfect ‘pitch’ at gain 25 dB.
The final result for High Velocity Cloud CIII with my 1.8 meter dish:
