2019 Western Conference Program and Abstracts

2019 Western Conference

Program and Abstracts


Monitoring Low Frequency Propagation with a Software Defined Radio Receiver

Part I ~ Propagation Concepts and Part II ~Observations

Whitham D. Reeve


The effects of a solar flare on terrestrial radio propagation may be detected by monitoring variations in the signals received from a low frequency transmitter. The signal variations caused by a flare are called a sudden ionospheric disturbance or SID.


Part I reviews low frequency propagation and how monitoring low frequency communication signals may be used to indirectly observe solar flares through SID detection, and Part II discusses the instrumentation and shows examples of signals received at Cohoe Radio Observatory in Alaska from low frequency transmitters around the world.  For purposes of this paper, low frequencies refer to frequencies in the VLF band (3 to 30 kHz) and lower part of the LF band (30 to 300 kHz) up to approximately 50 kHz. These low frequencies most often are used in secure one-way military submarine communications, and the transmitters typically use very large antenna systems requiring thousands of square kilometers land area and output powers up to slightly more than one megawatt.


CRO uses a software defined radio (SDR) receiver and a square loop antenna with balanced feed. The propagation examples in this paper were produced in the second half of 2018 as the solar cycle approached its minimum. Although the receiver and antenna system were built to detect sudden ionospheric disturbances, it is not surprising that no SIDs were detected at the time because of the low point in the solar cycle and the paucity of significant flares during the measurement period. However, the setup and observations described here provide a path for future investigations during the next solar cycle.


Preliminary Earth’s Orbital Position in the Milky Way

using HI Measurements

Richard A. Russel

Deep Space Exploration Society


The Sun moves in an almost circular path around the Milky Way. The Earth orbits the Sun at one astronomical unit in an elliptical orbit. The goal of this study is to determine if HI measurements using the Haswell, Colorado 60-foot dish and the SpectraCyber system can be used to determine the Earth’s orbit orientation with reference to the Milky Way center. Multiple observations were taken of HI at the same galactic longitude degrees. The different Doppler shifts correspond to the Earth’s position at the times of observation. A Monte-Carlo model was developed to explore the Earth orbital parameters in order to match the observed Doppler shifts with the expected model. The measured results showed that the 60-degree angle of the Earth’s orbit to the galactic plane showed good correlation. The date the Earth’s orbit has the closest approach to the galactic center at galactic longitude 0, was measured as July 12 versus the expected June 22, 2018.


Milky Way Rotation Rate and Mass Estimation

Using HI Measurements:

Latest Updates

Richard A. Russel

Deep Space Exploration Society


The measurement of the Milky Way rotation rate is a basic for HI radio astronomy. The Deep Space Exploration Society’s 60-foot dish in Haswell, Colorado has recently come online with a 1420 MHz feed and SpectraCyber system. This paper documents the conduct of the HI measurements that resulted into the production of a galactic rotation curve and a good estimate of galactic mass. This is an update to the paper in the Nov-Dec 2018 SARA Radio Astronomy Journal. Extra observations were taken to fill in the rotation curve especially closer to the galactic center.


Simultaneous and Associated Pulses Observed

 with Synchronized and Distant Radio Telescopes

Skip Crilly



A system of two GPS-synchronized radio telescopes has been utilized to search for celestial pulses, hypothetically due to ETI transmissions. One telescope is the Forty Foot Educational Telescope in Green Bank, West Virginia, while the other telescope is the Sixty Foot Paul J. Plishner Telescope near Haswell, Colorado. During the period of late 2017 through late 2018, in multiple synchronized observation runs, we recorded pulses while attempting to falsify a hypothesis of the presence of ETI-sourced modulated signals. This paper presents the RFI problem in SETI, concepts compelling the two-telescope system, simultaneous and associated pulse observations, the working hypothesis and plans for system improvement.


The Little Thompson Observatory 21cm radio telescope

Terry Bullett, Dave Eckhardt, Jay Wilson, Kevin McManus, Ted Cline,

Meinte Veldhuis, and Glenn Hetchler

Little Thompson Observatory, Berthoud, Colorado


This presentation provides a detailed description of the hardware, software, calibration methods and data processing used at Little Thompson Observatory (LTO) for 21cm radio astronomy. First light for this telescope was 16Feb17 for narrow band data and 05Aug18 for broadband hydrogen line data. This presentation focuses on the broadband hydrogen line data.


The LTO 21cm telescope system consists of a 12x14 foot off-center focus parabolic dish, 3.8m effective
 diameter, with limited manual pointing capability. The antenna is typically pointed due south with an allowed range of elevation angles between 10 and 90 degrees. The feed point consists of a resonant loop antenna in front of a 12" splash plate, two low-noise preamps, a front end 1 GHz high pass filter to reduce interference from nearby cell phone transmitters, and a pass-band filter of 1420-1470 MHz. The feed point is connected to the receiver by 100 ft of low-loss heliax coaxial cable. The feed point electronics are powered using the coax and a bias tee. The receiver consists of a bias tee, another gain stage, DC power and an Airspy software defined receiver (SDR) inside a small refrigerator for thermal stability. The Airspy receiver is connected to a Windows 7 computer running SDR# and Radio Sky Pipe.  The SDR# configuration is augmented with software plugins which allow frequency lock and broadband IQ data recording.


The IQ data recording feature allows the saving of  In-phase and Quadrature (IQ) raw data samples at the 10 MHz sampling rate of the Airspy receiver. These are saved as .WAV format data files with a maximum size of 2048 MB. The software automatically closes one file and opens another when the specified file size is exceeded. Data are saved in either 16 bit integers or 32 bit floating point and files contain approximately 60 or 30 seconds of broadband data. A 6TB disk drive on the collection computer offers many hours of continuous data recording. Data are manually transferred by Gigabit Ethernet to a multi-processor Linux server with a 32TB disk array.


The Level 0 Raw Data Records are processed by a custom FORTRAN program to compute spectra, perform calibrations, remove artifacts and compute spectral characteristics. These Level 2 Sensor Data Records, along with extensive metadata, are stored in a compact binary format with one averaged spectrum per file.


Plots of these spectra versus time are our basic drift scan product. Hydrogen line emissions, continuum radiation and HI absorption lines have been observed. The time series of spectra are further analyzed by a Python program to identify regions of HI emissions and measure total HI power.


The LTO 21cm hydrogen line telescope was used by the 2018 Berthoud High School Science, Technology, Engineering and Math (STEM) students to observe the region around the center of the Milky Way Galaxy.


Saturday Dinner

and Visit to Little Thompson Observatory


Saturday dinner will be at the Three Margaritas restaurant, 2350 Main St, Longmont, CO 80501. The restaurant is a casual setting and they offer a varied menu of Mexican, Tex-Mex and American entrees, along with complete beverage service.   Website:  http://3margaritasrestaurants.com/longmont-menu


Following dinner, at about 7:30 p.m. SARA attendees are invited to travel another eight miles north to the Little Thompson Observatory in the town of Berthoud for a welcoming address by Meinte Veldhuis, President of the Little Thompson Science Foundation, and a tour of the facility including telescope domes and the radio telescope installation.  Dr. Terry Bullett, David Eckhardt and Jay Wilson will provide introductions to the various radio astronomy experiments currently being conducted, and members of the Berthoud High School STEM program will be available to discuss their radio astronomy projects. 


If the skies are clear, LTO volunteers will open the two domes for spectacular viewing through 24-inch and 18-inch telescopes.


For more information about the observatory, including driving directions, please visit:  www.starkids.org


The Future of Radio Astronomy:

The SKA and ngVLA


Dayton Jones

Space Science Institute, Boulder (part-time)

Jet Propulsion Laboratory, California Institute of Technology, Pasadena (retired)

Former US representative to the SKA Science and Engineering Steering Committee and

officer of the US SKA Consortium



The Square Kilometer Array (SKA), currently in the detailed design phase, and the Next Generation Very Large Array (ngVLA), expected to be proposed in the early 2020s, will together provide a vast increase in radio astronomy capabilities at frequencies from 50 MHz to 116 GHz.  These future facilities will be sited in southern Africa, western Australia, and the southwestern US.  Along with the existing Atacama Large Millimeter Array (ALMA) in Chile we will have an orders-of-magnitude increase in sensitivity, survey speed, and imaging quality at all radio wavelengths observable from the surface of the Earth.  This will revolutionize a wide range of key scientific areas from our solar system to the earliest epochs of the universe and fundamental questions of cosmology.  In addition, the SKA will potentially change the sociology of radio astronomy by providing, at low and mid-frequencies, a number of simultaneous, independently steerable beams each having the full array sensitivity.  This flexibility could allow a broader base of users to have access to a forefront instrument, and riskier types of observations to be attempted.


This talk will review the major science goals for the SKA and ngVLA, describe the current designs, and discuss some of the technical challenges that remain.


Rebuilding Public-access astronomy in Puerto Rico

Eric Muhs

Guest speaker and award-winning science teacher



In September 2017, Hurricane María made a direct hit on Puerto Rico. The damage was catastrophic, and the worst natural disaster in Puerto Rico’s history. Recovery efforts since are widely acknowledged to have been grossly inadequate. Even the official death toll is in dispute, with notoriously low numbers recently revised upwards, and now estimated close to 10,000.


Approximately 10 percent of the survivors have left the island, likely permanently. The electrical grid remains fragile; even a common afternoon thunderstorm is likely to cause an outage. Many traffic lights and street lights are still unrepaired, and a significant portion of pre-hurricane housing is still not usable. Of course, the priority after the hurricane was to restore necessities, like food, water, shipping, and transportation. San Juan, among the 35 largest cities in the United States, did not get to above 90% electricity restoration until 6 months after the disaster, and some rural areas are still not fully restored, 18 months later. Non-emergency projects like education could not be advanced until many months later.


Puerto Rico is uniquely situated in the political orbit of the United States. Citizens can’t vote in national elections, and thus have little influence over the politicians and policies that guide development and investment on the island. The mainland United States, therefore, bears a very significant responsibility for the island’s welfare. It is in that spirit that AEwPR (Astronomy Education with Puerto Rico) was created.


Eric Muhs, an award winning educator from Seattle, is working with AEwPR on the construction of a modest public-access observatory on the campus of Ana G. Méndez University in San Juan. This project was in talks before the disaster, and can finally move forward again. The observatory will be run in partnership with the PRAS (Puerto Rico Astronomy Society), which is well-positioned for the management of this project. University staff are excited as well: the university was recently awarded the contract for all outreach work for the Arecibo Radio Observatory, Puerto Rico’s most well-known and significant major astronomical research facility.


Improving the Low-Cost RTL-SDR 1420 MHz Receiver

Hans Gaensbauer

Deep Space Exploration Society



Several systems for measuring hydrogen spectra using an RTL-SDR have been described which allow astronomers to study galactic neutral hydrogen without needing expensive equipment. While RTL-SDR offers many advantages including low cost, ease of use, and minimal setup, the limited hardware means that observations made with RTL-SDR are susceptible to errors from temperature drift. Additionally, a lack of dedicated software makes coordinated and consistent data acquisition difficult. Here, we present solutions to the problems with RTL-SDR-based receivers, with an emphasis on simplicity and affordability. The final setup requires only the dongle, low-cost wideband amplifiers, and a custom built SI5332A-based clock generator which can be used to lock the SDR clock to an external signal or temperature controlled external oscillator. The entire system costs less that $50, and allows much smaller and lower cost antennas to be used with increased resolution.


Drift-scan imaging with the Plishner radiotelescope:

Preliminary Results

Tony Bigbee

Deep Space Exploration Society


This paper presents preliminary results from continuum drift scan imaging performed by the Deep Space Exploration Society Plishner 18-meter radiotelescope in Haswell, CO. The goal of the research is to explore drift scan planning, pointing, and post-processing techniques for image map construction.  Since tracking services are not yet available, current collection consists of a "point and shoot" approach to build raster lines by drift scanning in right ascension, and repointing to another declination at the end of each raster line.  A primary consideration of this technique is spatial (over)sampling.  Right ascension collection and spatial resolution derives from the constant rate of the earth's revolution, while declination collection and spatial resolution is a function of both pointing precision/accuracy and a choice about beam pattern overlap in declination.