Polarized synchrotron emission at meter to centimeter wavelengths provides an effective tracer of the Galactic magnetic field. Calculating Faraday depth, the most useful parameter for mapping the line-of-sight magnetic field, requires observations covering wide frequency bands with many channels. As part of the Global Magneto-Ionic Medium Survey (GMIMS), we have observed polarized emission spanning 350–1030 MHz over the northern sky, in the declination range −20° ≤ δ ≤ 90°. We used the 15 m telescope at the Dominion Radio Astrophysical Observatory (DRAO), equipped to receive orthogonal circular polarizations, with the Onsala Space Observatory band 1 feed developed for the SKA Project. Angular resolution varies across the band from 1:3 to 3:6. A digital spectrometer provided 42 kHz frequency resolution. Data were taken with the telescope moving rapidly in azimuth and are absolutely calibrated in intensity. Approximately 25% of the data were lost due to radio-frequency interference. The resolution in Faraday depth is ∼6 rad m−2, and features as wide as ∼38 rad m−2 are represented. The median sensitivity of the Faraday depth cube is 11 mK. Approximately 55% of sight lines in this survey show Faraday complexity. This dataset, called “DRAO GMIMS of the Northern Sky,” is the first to probe Faraday depth of the northern sky in its frequency range and will support many scientific investigations. The data will be used to calibrate surveys with higher angular resolution, particularly Galactic foreground maps from the Canadian Hydrogen Intensity Mapping Experiment, and to provide information on large structures for aperture-synthesis telescopes, particularly the DRAO Synthesis Telescope. The data are available through the Canadian Astronomy Data Centre.
", "doi": "10.3847/1538-4365/ae2471", "issn": "0067-0049", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Supplement Series", "publication_date": "2026-02", "series_number": "2", "volume": "282", "issue": "2", "pages": "53" }, { "id": "authors:c0jv6-n8j96", "collection": "authors", "collection_id": "c0jv6-n8j96", "cite_using_url": "https://authors.library.caltech.edu/records/c0jv6-n8j96", "type": "conference_item", "title": "DSA-2000 Feed and Antenna System Performance", "book_title": "2025 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)", "author": [ { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" } ], "abstract": "The Deep Synoptic Array (DSA-2000) will be a world-leading radio astronomical survey telescope with unprecedented survey speed and sensitivity. It is based on an array of 2000 reflector antennas each with 5 m diameter and will span an area of 15 km x 19 km in Nevada, USA (G. Hallinan et al., Astro2020 51(7), 2019). Each antenna will be equipped with a high-sensitivity, low-cost feed package covering 0.7-2 GHz based on a ground-breaking ambient temperature low-noise amplifier (LNA) with 11 K noise temperature (J. Shi & S. Weinreb, IEEE-MTT 2023, pp. 1540\u20131543). The predicted system noise temperature is less than 25 K.", "doi": "10.23919/usnc-ursinrsm66067.2025.10907103", "isbn": "9798331513979", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication": "2025 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM)", "publication_date": "2025-01-07/2025-01-10", "pages": "412" }, { "id": "authors:hd43t-79q37", "collection": "authors", "collection_id": "hd43t-79q37", "cite_using_url": "https://authors.library.caltech.edu/records/hd43t-79q37", "type": "conference_item", "title": "Wideband Low-Loss Feed Design for the DSA-2000 Ambient Temperature Array in Radio Astronomy", "book_title": "2024 IEEE International Symposium on Antennas and Propagation and INC/USNC\u2010URSI Radio Science Meeting (AP-S/INC-USNC-URSI)", "author": [ { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" } ], "abstract": "The Deep Synoptic Array (DSA-2000) is the next generation ground-based radio astronomical array that will consist of 2000×5 m reflectors equipped with an ambient temperature feed package and electronics covering 0.7-2 GHz. The quad-ridge choke horn (QRCH) feed developed for the DSA-2000 is a wideband, low-loss, and low-cost design providing a wide radiation pattern to illuminate the deep prime-focus reflector. We present the predicted noise temperature contributions for the feed, low-noise amplifiers, and surrounding brightness - resulting in a remarkable 25 K system noise at ambient temperature.
", "doi": "10.1109/ap-s/inc-usnc-ursi52054.2024.10686435", "isbn": "9798350369915", "publisher": "IEEE", "place_of_publication": "Piscataway, N . J.", "publication": "2024 IEEE International Symposium on Antennas and Propagation and INC/USNC\u2010URSI Radio Science Meeting (AP-S/INC-USNC-URSI)", "publication_date": "2024-07-14/2024-07-19", "pages": "5-6" }, { "id": "authors:01fgt-32j85", "collection": "authors", "collection_id": "01fgt-32j85", "cite_using_url": "https://authors.library.caltech.edu/records/01fgt-32j85", "type": "conference_item", "title": "Wideband Feed and Reflector Ground Shield for the Deep Synoptic Array (DSA-2000)", "book_title": "2023 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (USNC-URSI)", "author": [ { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" }, { "family_name": "Woody", "given_name": "David P.", "clpid": "Woody-D-P" } ], "abstract": "We present the low-cost, dual-polarized, wideband quad-ridge choke horn (QRCH) feed with a low-loss dielectric lid optimized for the Deep Synoptic Array (DSA-2000) in radio astronomy. The ridges and dielectric lid allows for a compact feed diameter with small blockage of the 5-meter-diameter axially-symmetric prime-focus reflector. A wide feed pattern suitable for applications with f/D below 0.35 is achieved over the frequency range 0.7-2 GHz. The band-average aperture efficiency in simulation is 66 % in the unshaped reflector including blockage. An extension of the reflector rim reduces the spillover noise contribution to less than 1 K at zenith pointing. Together with an excellent ambient temperature low-noise amplifier developed for DSA-2000 the predicted system noise temperature is 25 K.", "doi": "10.1109/usnc-ursi52151.2023.10237516", "isbn": "9781665442299", "publisher": "IEEE", "place_of_publication": "Piscataway, N. J.", "publication": "2023 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (USNC-URSI)", "publication_date": "2023-07-23/2023-07-28", "pages": "761-762" }, { "id": "authors:t8tpz-zh473", "collection": "authors", "collection_id": "t8tpz-zh473", "cite_using_url": "https://authors.library.caltech.edu/records/t8tpz-zh473", "type": "conference_item", "title": "Beam holography of OVRO-LWA antennas using the OVRO 40-m telescope", "book_title": "2023 IEEE Radio and Antenna Days of the Indian Ocean (RADIO)", "author": [ { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" } ], "abstract": "The OVRO-LWA radio telescope is an array of 352 dipole antennas optimized for high red-shift 21-cm cosmology and the detection of magnetospheric radio emission from exoplanets. These scientific cases impose some strict calibration requirements including a very accurate knowledge of the beam for each antenna in the array. This paper outlines a conceptual design to map the beams using pulsar holography. The technique will use the 40-m dish with a feed similar to a single dipole pair in the array, which will drastically increase the sensitivity. Another method is also discussed where the phased array beam is used instead of the dish potentially giving better results.", "doi": "10.1109/radio58424.2023.10146052", "isbn": "9798350347920", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2023-05-01/2023-05-04", "pages": "1-2" }, { "id": "authors:3hbyn-ebp52", "collection": "authors", "collection_id": "3hbyn-ebp52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210202-095231043", "type": "article", "title": "Galactic Radio Explorer: An All-sky Monitor for Bright Radio Bursts", "author": [ { "family_name": "Connor", "given_name": "Liam", "orcid": "0000-0002-7587-6352", "clpid": "Connor-Liam-D" }, { "family_name": "Shila", "given_name": "Kiran A.", "orcid": "0000-0003-4652-7038", "clpid": "Shila-Kiran-A" }, { "family_name": "Kulkarni", "given_name": "Shrinivas R.", "orcid": "0000-0001-5390-8563", "clpid": "Kulkarni-S-R" }, { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Li", "given_name": "Dongzi", "orcid": "0000-0001-7931-0607", "clpid": "Li-Dongzi" }, { "family_name": "Lu", "given_name": "Wenbin", "orcid": "0000-0002-1568-7461", "clpid": "Lu-Wenbin" }, { "family_name": "Ravi", "given_name": "Vikram", "orcid": "0000-0002-7252-5485", "clpid": "Ravi-Vikram" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" } ], "abstract": "We present the Galactic Radio Explorer (GReX), an all-sky monitor to probe the brightest bursts in the radio sky. Building on the success of STARE2, we will search for fast radio bursts emitted from Galactic magnetars as well as bursts from nearby galaxies. GReX will search down to ~ ten microseconds time resolution, allowing us to find new super giant radio pulses from Milky Way pulsars and study their broadband emission. The proposed instrument will employ ultra-wide band (0.7\u20132 GHz) feeds coupled to a high-performance (receiver temperature <10 K) low noise amplifier originally developed for the DSA-110 and DSA-2000 projects. In GReX Phase I (GReX-I), unit systems will be deployed at Owens Valley Radio Observatory and Big Smoky Valley, Nevada. Phase II will expand the array, placing feeds in India, Australia, and elsewhere in order to build up to continuous coverage of nearly 4\u03c0 steradians and to increase our exposure to the Galactic plane. We model the local magnetar population to forecast for GReX, finding the improved sensitivity and increased exposure to the Galactic plane could lead to dozens of FRB-like bursts per year.", "doi": "10.1088/1538-3873/ac0bcc", "issn": "0004-6280", "publisher": "Astronomical Society of the Pacific", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2021-07-01", "series_number": "1025", "volume": "133", "issue": "1025", "pages": "Art. No. 075001" }, { "id": "authors:2pd4j-qt987", "collection": "authors", "collection_id": "2pd4j-qt987", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181213-154116277", "type": "book_section", "title": "Cryogenic 1.2 to 116 GHz receiver for large arrays", "book_title": "12th European Conference on Antennas and Propagation (EuCAP 2018)", "author": [ { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Mani", "given_name": "Hamdi", "clpid": "Mani-H" }, { "family_name": "Zhong", "given_name": "Weiye", "clpid": "Zhong-Weiye" }, { "family_name": "Flygare", "given_name": "Jonas", "orcid": "0000-0002-0204-2891", "clpid": "Flygare-Jonas" }, { "family_name": "Billade", "given_name": "Bushan", "clpid": "Billade-B" }, { "family_name": "Akgiray", "given_name": "Ahmed", "orcid": "0000-0002-7373-4158", "clpid": "Akgiray-A" }, { "family_name": "Dong", "given_name": "Li", "clpid": "Dong-Li" } ], "abstract": "Current and future large arrays for radio astronomy are compared and the Next Generation Very Large Array, ngVLA, is introduced. Receiver requirements are described and a 4-feed system covering 1.2 to 116 GHz, in a single vacuum cryogenic enclosure is presented followed by description of the reflector optics, the wide-band feeds, and the expected system performance.", "doi": "10.1049/cp.2018.0821", "isbn": "978-1-78561-815-4", "publisher": "IEEE", "place_of_publication": "Piscataway, NJ", "publication_date": "2018-04", "pages": "1-4" } ]