Wow@Home

Introduction

A network of small radio telescopes offers several distinct advantages compared to large professional observatories. These systems are low-cost and can operate autonomously around the clock, making them ideal for continuous monitoring of transient events or long-duration signals that professional telescopes cannot commit to observing full-time.

Their geographic distribution enables global sky coverage and coordinated observations across different time zones, which is especially valuable for validating repeating or time-variable signals. Coincidence detection across multiple stations helps reject local radio frequency interference (RFI), increasing confidence in true astrophysical or technosignature candidates.

These networks are also highly scalable, resilient to single-point failures, and capable of rapid response to external alerts. Furthermore, they are cost-effective, engaging, and accessible, ideal for education, citizen science, and expanding participation in radio astronomy.

However, these systems also come with notable limitations when compared to professional telescopes. They have significantly lower sensitivity, limiting their ability to detect faint or distant sources. Their angular resolution is poor due to smaller dish sizes and wide beamwidths, making precise source localization difficult.

Calibration can be inconsistent across stations, and frequency stability or dynamic range may not match the performance of professional-grade equipment. Additionally, without standardized equipment and protocols, data quality and interoperability can vary across the network. Despite these constraints, when thoughtfully coordinated, such networks can provide valuable complementary observations to professional facilities.

The Wow@Home Radio Telescope

This page presents a test of our first Wow@Home Radio Telescope hardware and software configuration (Figure 1). The system is tested for a network of small radio telescopes designed to emulate, as closely as possible, the observation protocol of the meridian radio telescope Big Ear used by the Ohio SETI project in the 1970s. As in the original setup, we use a 10 kHz channel width and a 12-second integration time. However, our system differs in several ways: it features 256 channels instead of 50, a much larger beam size, but significantly lower sensitivity.

The telescope is fixed at a constant elevation, pointed south, and scans a specific celestial declination over the course of one or more days using a wide field of view of approximately 25° (HPBW or its beamwidth). As the Earth rotates, this configuration allows the telescope to capture a continuous 360° strip of the sky at that declination. After completing three or more full-sky passes, the telescope is adjusted to a new elevation to begin scanning a different declination, gradually building up full-sky coverage over time.

While optimized for educational use, this configuration also yields valuable data on RFI near the H I line in urban environments, helping us assess the likelihood of RFI mimicking a Wow!-like signal. Additionally, it serves as a practical platform for a wide-field search for strong transient events, whether of astrophysical origin or potential technosignatures.

For events that persist longer than a day, multiple observing passes can be used to validate their presence, detect weaker features, improve overall sensitivity, and help distinguish them from RFI. Additionally, simultaneous observations by two or more telescopes pointed at the same location can further aid in rejecting local interference and confirming the reality of signals that last less than 24 hours.

The Wow@Home Radio Telescope operates autonomously, 24/7, as a meridian-style instrument, conducting a continuous all-sky survey for transient events. The hardware required to build these telescopes is both inexpensive and widely accessible, relying on readily available components. The critical element lies in the software, which must be capable of analyzing data effectively, whether from a single station or across a coordinated network of telescopes.

Future expansions could include the integration of multibeam systems to enable simultaneous ON–OFF observations to improve sensitivity, tracking capability to perform targeted observations of specific sources, multi-site detection for signal validation, higher sensitivity, and RFI discrimination, interferometric capabilities for improved angular resolution, and phased array configurations to enhance sensitivity and enable electronic beam steering.

Figure 1: Components of our first Wow@Home Radio Telescope. The Easy Radio Astronomy (ezRA) software is an excellent starter package for getting this configuration up and running for radio astronomy. We plan to test additional configurations in the coming months, including the Discovery Dish, which integrates the frontend into the antenna, and the Airspy Mini as the backend, offering a 12-bit ADC for improved dynamic range.

The Wow@Home Software

The Wow@Home Software is the core of our project. It serves as the data acquisition and analysis platform designed to search for transient events caused by astrophysical phenomena, potential technosignatures, and RFI characterization, using data from any small radio telescope. The software is built on the analysis methods we are developing to detect Wow-like signals in the archive data of professional observatories, as part of our Arecibo Wow! Project. We are currently developing the software in IDL, with example outputs shown in Figures 2, 3, and 4. It will later be translated to Python to ensure cross-platform compatibility and broader accessibility.

Figure 2: This is a test run of the Wow@Home Radio Telescope. The top panel shows the relative power as a function of time. The next panel is the signal-to-noise ratio (SNR). Most RFI here originates from continuum sources, which are relatively easy to filter out. The following dynamic spectra images show three different ways to analyze the data, depending on the type of signal of interest. The broadband SNR is suitable for detecting continuum sources, but RFI heavily contaminates it. A second telescope at a different location could be used to cross-correlate astronomical signals. The mediumband SNR is good for highlighting the Galactic center transiting after 6 hours and the Galactic anticenter about 12 hours later. The narrowband SNR is more sensitive to signals occurring in only one channel. The horizontal line at channel 224 is an injected test signal spanning the telescope’s beamwidth. An actual narrowband RFI event is visible near channel 0 after 15 hours.

Figure 3: Neutral Hydrogen (H I) spectral profile of the Galactic center, extracted from the data in Figure 2 at 6.5 hours. Error bars represent the 1σ uncertainty in each frequency channel.

Figure 4: In addition to the modern analysis tools available with today’s radio telescopes, we also aim to incorporate into our software the ability to generate a live preview of the data in the style of the original Ohio State SETI project printouts. This feature is intended to provide historical context and connect current efforts to the legacy of early SETI research. Above is an example using the original Wow! Signal data.

For more information, contact [email protected].