CHIME/FRB Outriggers: KKO Station System and Commissioning Results

CHIME/FRB Outriggers: KKO Station System and Commissioning Results

May 30, 2024 | Adam E. Lanman, Shion Andrew, Mattias Lazda, Vishwangi Shah, Mandana Amiri, Arvind Balasubramanian, Kevin Bandura, P. J. Boyle, Charanjot Brar, Mark Carlson, Jean-François Cliche, Nina Guisinskaia, Ian T. Hendrickson, J. F. Kaczmarek, Tom Landecker, Calvin Leung, Ryan Mckinven, Juan Mena-Parra, Nikola Milutinovic, Kenzie Nimmo, Aaron B. Pearlman, Andre Renard, Mubdi Rahman, J. Richard Shaw, Seth R. Siegel, Rick J. Smegal, Tomas Cassanelli, Shami Chatterjee, Alice P. Curtin, Matt Dobbs, Fengqiu Adam Dong, Mark Halpern, Hans Hopkins, Victoria M. Kaspi, Kholoud Khairy, Kiyoshi W. Masui, Bradley W. Meyers, Daniele Michilli, Emily Petroff, Tristan Pinsonneault-Marotte, Ziggy Pleunis, Masoud Rafiei-Ravandi, Kaitlyn Shin, Kendrick Smith, Keith Vanderlinde, and Tarik J. Zegmott
The CHIME/FRB Outriggers program aims to enhance the localization of fast radio bursts (FRBs) by adding VLBI capabilities to the CHIME telescope. The first outrigger, KKO, is located 66 km west of CHIME and is designed to achieve arcsecond-scale resolution while avoiding ionospheric effects. KKO's performance was evaluated during its commissioning phase, and it demonstrated the ability to produce full-sky images, map the angular and frequency structure of the primary beam, and measure feed positions. The KKO-CHIME baseline was used to localize 20 pulsars to within 5 arcseconds, achieving the desired precision. The next two outriggers are expected to be commissioned in 2024, enabling subarcsecond localizations for hundreds of FRBs annually. The KKO system is similar to CHIME in design, with a cylindrical paraboloid reflector 20 meters wide and 40 meters long. It has a 5-meter focal length and is aligned to see the same sky as CHIME. The system includes a receiver chain with dual-polarization feeds, amplifiers, and filters. A custom bandstop filter was installed to suppress LTE signals in the 710-757 MHz range. The digital backend is an FX correlator, with an F-engine for sampling and frequency channelization, and an X-engine for data processing and cross-correlation. The X-engine is a 128-input correlator with a 2-node cluster, capable of handling high data throughput. The KKO system includes a clocking system for timing and synchronization, with a GPS-disciplined crystal oscillator and a Rubidium clock for stability. The system also has a real-time data processing pipeline for triggered baseband recording and visibility calculations. The KKO system has demonstrated stability and robustness during its commissioning phase, with occasional power outages being resolved quickly. The system has recorded data for 85% of the year and completed over 1000 triggered baseband dumps. The KKO system has been characterized for its performance as a standalone telescope, with measurements of system noise, RFI environment, and correlation strengths. The primary beam was mapped during a solar transit, showing the hour angle and frequency structure. The RFI environment was analyzed, and a static RFI mask was constructed to remove contaminated channels. The system equivalent flux density (SEFD) was characterized, showing consistent results with CHIME. The system has also been tested with a radiometer test, confirming the expected behavior of the autocorrelation power. Overall, the KKO system has proven to be a valuable addition to the CHIME/FRB program, enabling more precise localization of FRBs and enhancing our understanding of their origins.The CHIME/FRB Outriggers program aims to enhance the localization of fast radio bursts (FRBs) by adding VLBI capabilities to the CHIME telescope. The first outrigger, KKO, is located 66 km west of CHIME and is designed to achieve arcsecond-scale resolution while avoiding ionospheric effects. KKO's performance was evaluated during its commissioning phase, and it demonstrated the ability to produce full-sky images, map the angular and frequency structure of the primary beam, and measure feed positions. The KKO-CHIME baseline was used to localize 20 pulsars to within 5 arcseconds, achieving the desired precision. The next two outriggers are expected to be commissioned in 2024, enabling subarcsecond localizations for hundreds of FRBs annually. The KKO system is similar to CHIME in design, with a cylindrical paraboloid reflector 20 meters wide and 40 meters long. It has a 5-meter focal length and is aligned to see the same sky as CHIME. The system includes a receiver chain with dual-polarization feeds, amplifiers, and filters. A custom bandstop filter was installed to suppress LTE signals in the 710-757 MHz range. The digital backend is an FX correlator, with an F-engine for sampling and frequency channelization, and an X-engine for data processing and cross-correlation. The X-engine is a 128-input correlator with a 2-node cluster, capable of handling high data throughput. The KKO system includes a clocking system for timing and synchronization, with a GPS-disciplined crystal oscillator and a Rubidium clock for stability. The system also has a real-time data processing pipeline for triggered baseband recording and visibility calculations. The KKO system has demonstrated stability and robustness during its commissioning phase, with occasional power outages being resolved quickly. The system has recorded data for 85% of the year and completed over 1000 triggered baseband dumps. The KKO system has been characterized for its performance as a standalone telescope, with measurements of system noise, RFI environment, and correlation strengths. The primary beam was mapped during a solar transit, showing the hour angle and frequency structure. The RFI environment was analyzed, and a static RFI mask was constructed to remove contaminated channels. The system equivalent flux density (SEFD) was characterized, showing consistent results with CHIME. The system has also been tested with a radiometer test, confirming the expected behavior of the autocorrelation power. Overall, the KKO system has proven to be a valuable addition to the CHIME/FRB program, enabling more precise localization of FRBs and enhancing our understanding of their origins.
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