[ { "id": "https://authors.library.caltech.edu/records/2yfx1-j5d74", "eprint_id": 119502, "eprint_status": "archive", "datestamp": "2023-08-20 08:59:12", "lastmod": "2023-10-25 14:42:34", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ravi-Vikram", "name": { "family": "Ravi", "given": "Vikram" }, "orcid": "0000-0002-7252-5485" }, { "id": "Catha-Morgan", "name": { "family": "Catha", "given": "Morgan" } }, { "id": "Chen-Ge", "name": { "family": "Chen", "given": "Ge" }, "orcid": "0000-0003-2867-4544" }, { "id": "Connor-Liam-D", "name": { "family": "Connor", "given": "Liam" }, "orcid": "0000-0002-7587-6352" }, { "id": "Cordes-James-M", "name": { "family": "Cordes", "given": "James M." }, "orcid": "0000-0002-4049-1882" }, { "id": "Faber-Jakob-T", "name": { "family": "Faber", "given": "Jakob T." }, "orcid": "0000-0001-9855-5781" }, { "id": "Lamb-James-W", "name": { "family": "Lamb", "given": "James W." }, "orcid": "0000-0002-5959-1285" }, { "id": "Hallinan-G", "name": { "family": "Hallinan", "given": "Gregg" }, "orcid": "0000-0002-7083-4049" }, { "id": "Harnach-Charlie", "name": { "family": "Harnach", "given": "Charlie" } }, { "id": "Hellbourg-Gregory", "name": { "family": "Hellbourg", "given": "Greg" }, "orcid": "0000-0002-8191-3885" }, { "id": "Hobbs-Rick", "name": { "family": "Hobbs", "given": "Rick" } }, { "id": "Hodge-David-C", "name": { "family": "Hodge", "given": "David" } }, { "id": "Hodges-Mark-W", "name": { "family": "Hodges", "given": "Mark" } }, { "id": "Law-Casey-J", "name": { "family": "Law", "given": "Casey" }, "orcid": "0000-0002-4119-9963" }, { "id": "Rasmussen-Paul", "name": { "family": "Rasmussen", "given": "Paul" } }, { "id": "Sharma-Kritti", "name": { "family": "Sharma", "given": "Kritti" }, "orcid": "0000-0002-4477-3625" }, { "id": "Sherman-Myles-B", "name": { "family": "Sherman", "given": "Myles B." } }, { "id": "Shi-Jun", "name": { "family": "Shi", "given": "Jun" }, "orcid": "0000-0003-1647-7762" }, { "id": "Simard-Dana", "name": { "family": "Simard", "given": "Dana" }, "orcid": "0000-0002-8873-8784" }, { "id": "Somalwar-Jean-J", "name": { "family": "Somalwar", "given": "Jean J." }, "orcid": "0000-0001-8426-5732" }, { "id": "Squillace-Reynier", "name": { "family": "Squillace", "given": "Reynier" } }, { "id": "Weinreb-S", "name": { "family": "Weinreb", "given": "Sander" }, "orcid": "0000-0002-9353-6204" }, { "id": "Woody-David-P", "name": { "family": "Woody", "given": "David P." } }, { "id": "Yadlapalli-Nitika", "name": { "family": "Yadlapalli", "given": "Nitika" }, "orcid": "0000-0003-3255-4617" } ] }, "title": "Deep Synoptic Array science: a 50 Mpc fast radio burst constrains the mass of the Milky Way circumgalactic medium", "ispublished": "unpub", "full_text_status": "public", "note": "The authors thank staff members of the Owens Valley Radio Observatory and the Caltech radio group, including Kristen Bernasconi, Stephanie Cha-Ramos, Sarah Harnach, Tom Klinefelter, Lori McGraw, Corey Posner, Andres Rizo, Michael Virgin, Scott White, and Thomas Zentmyer. Their tireless efforts were instrumental to the success of the DSA-110. The DSA-110 is supported by the National Science Foundation Mid-Scale Innovations Program in Astronomical Sciences (MSIP) under grant AST-1836018. We acknowledge use of the VLA calibrator manual and the radio fundamental catalog. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. \n\nFacility: Hale \n\nSoftware: astropy, CASA, heimdall, pypeit, Prospector, wsclean\n\n
Submitted - 2301.01000.pdf
", "abstract": "We present the Deep Synoptic Array (DSA-110) discovery and interferometric localization of the so far non-repeating FRB 20220319D. The FRB originates in a young, rapidly star-forming barred spiral galaxy, IRAS 02044+7048, at just 50 Mpc. Although the NE2001 and YMW16 models for the Galactic interstellar-medium (ISM) contribution to the DM of FRB 20220319D exceed its total observed DM, we show that uncertainties in these models accommodate an extragalactic origin for the burst. We derive a conservative upper limit on the DM contributed by the circumgalactic medium (CGM) of the Milky Way: the limit is either 28.7 pc cm\u207b\u00b3 and 47.3 pc cm\u207b\u00b3, depending on which of two pulsars nearby on the sky to FRB 20220319D is used to estimate the ISM DM. These limits both imply that the total Galactic CGM mass is <10\u00b9\u00b9 M_\u2299, and that the baryonic mass of the Milky Way is \u227260% of the cosmological average given the total halo mass. More stringent albeit less conservative constraints are possible when the DMs of pulsars in the distant globular cluster M53 are additionally considered. Although our constraints are sensitive to possible anisotropy in the CGM and to the assumed form of the radial-density profile, they are not subject to uncertainties in the chemical and thermal properties of the CGM. Our results strongly support scenarios commonly predicted by galaxy-formation simulations wherein feedback processes expel baryonic matter from the halos of galaxies like the Milky Way.", "date": "2023-02-28", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20230224-200149560", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230224-200149560", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1836018" }, { "agency": "W. M. Keck Foundation" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" }, { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.48550/arXiv.2301.01000", "primary_object": { "basename": "2301.01000.pdf", "url": "https://authors.library.caltech.edu/records/2yfx1-j5d74/files/2301.01000.pdf" }, "pub_year": "2023", "author_list": "Ravi, Vikram; Catha, Morgan; et el." }, { "id": "https://authors.library.caltech.edu/records/xtsmm-q9f51", "eprint_id": 114963, "eprint_status": "archive", "datestamp": "2023-08-20 07:43:19", "lastmod": "2023-10-24 15:16:32", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Connor-Liam-D", "name": { "family": "Connor", "given": "Liam" }, "orcid": "0000-0002-7587-6352" }, { "id": "Ravi-Vikram", "name": { "family": "Ravi", "given": "Vikram" }, "orcid": "0000-0002-7252-5485" } ] }, "title": "The observed impact of galaxy halo gas on fast radio bursts", "ispublished": "unpub", "full_text_status": "public", "note": "Attribution 4.0 International (CC BY 4.0).\n\nWe first the referees, whose careful consideration and suggestions were invaluable. We thank Cameron Hummels, Wenbin Lu, J. Michael Shull, and the Caltech FRB group for a helpful discussions. We also thank Calvin Leung, Kiyoshi Masui, and Mohit Bhardwaj for valuable comments on the manuscript. This research was partially supported by the National Science Foundation under grant AST-1836018.\n\nAccepted Version - 2107.13692.pdf
", "abstract": "Galaxies and groups of galaxies exist in dark-matter halos filled with diffuse gas. The diffuse gas represents up to 80% of the mass in baryonic matter within the halos, but is difficult to detect because of its low density (particle number densities of \u2272 10\u207b\u2074 cm\u207b\u00b3) and high temperature (mostly greater than 10\u2076 K). Here we analyze the impact of diffuse gas associated with nearby galaxies using the dispersion measures (DMs) of extragalactic fast radio bursts (FRBs). FRB DMs provide direct measurements of the total ionized-gas contents along their sightlines. Out of a sample of 474 distant FRBs from the CHIME/FRB Catalog 1, we identify a subset of events that likely intersect the dark-matter halos of galaxies in the local Universe (< 40 Mpc). The mean DM of the galaxy-intersecting FRBs is larger than the non-intersecting DMs with probability > 0.99 and the excess DM is > 90 pc cm\u207b\u00b3 with > 95% confidence. The excess is larger than expected for the diffuse gas surrounding isolated galaxies, but may be explained by additional contributions from gas surrounding galaxy groups, including from the Local Group. This result demonstrates the predicted ability of FRBs to be used as sensitive, model-independent measures of the diffuse-gas contents of dark-matter halos.", "date": "2023-02-15", "date_type": "published", "id_number": "CaltechAUTHORS:20220531-161251395", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220531-161251395", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST-1836018" } ] }, "local_group": { "items": [ { "id": "Astronomy-Department" }, { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.48550/arXiv.2107.13692", "primary_object": { "basename": "2107.13692.pdf", "url": "https://authors.library.caltech.edu/records/xtsmm-q9f51/files/2107.13692.pdf" }, "pub_year": "2023", "author_list": "Connor, Liam and Ravi, Vikram" }, { "id": "https://authors.library.caltech.edu/records/ar7f2-qem77", "eprint_id": 119268, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:50", "lastmod": "2024-01-15 21:30:31", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Analog Signal Path Analysis for Fiber-Connected Antennas of LWA352", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo13.pdf
", "abstract": "The OVRO LWA is subject to strong RFI at frequencies outside the nominal observing\nband, 20-85 MHz. This includes FM radio (88-108 MHz) and HF communication (<20 MHz).\nIntermodulation among these RFI signals can produce undesired signals in the observing band.\nThe current design of the signal path includes strong filtering of the out-of-band signals,\nbut that filtering occurs after the front end electronics (FEE, 36 dB gain) and after the first\namplifier stage of the analog receiver (ARX, 23 dB). For the fiber-coupled antennas, it is also\nafter the optical link. These amplifiers and the optical link are not perfectly linear, so they can\nproduce intermodulation. They are designed to tolerate the known RFI, but some\nintermodulation still occurs. To minimize this residual intermodulation, signal levels at these\ncomponents should be small. On the other hand, the signal path must have sufficient gain,\nproperly distributed, to avoid having downstream components add significantly to the system\nnoise temperature.\nThis memo provides a quantitative analysis of the trade-off between intermodulation and\nnoise temperature. It concentrates on the fiber-connected antennas. The coax-connected\nantennas have a similar issue, but whereas the coax cable can be considered completely linear\nthere is less intermodulation and the ARX has sufficient gain to keep the noise impact small,\neven for the longest cables.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-222614049", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-222614049", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/ayx8-9r19", "primary_object": { "basename": "memo13.pdf", "url": "https://authors.library.caltech.edu/records/ar7f2-qem77/files/memo13.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/c3jxf-zsw71", "eprint_id": 119260, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:15", "lastmod": "2024-01-15 21:30:19", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bowman-Judd", "name": { "family": "Bowman", "given": "Judd" }, "orcid": "0000-0002-8475-2036" } ] }, "title": "Cable Reflections in Autocorrelation Delay Spectra", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo7.pdf
", "abstract": "For the Cosmic Dawn key science goal of detecting the redshifted 21cm signal around redshift z=17 with\nOVRO-LWA-352, we wish to minimize spectral structure in the uncalibrated bandpass of the instrument.\nAn effective method to quantify bandpass spectral structure is to use the delay spectrum of the bandpass.\nThe delay spectrum is the Fourier transform along frequency of the bandpass. In this memo, we briefly\nreview the delay spectrum as it pertains to redshifted 21cm Cosmic Dawn measurements and then analyze\nexisting OVRO-LWA autocorrelation spectra as a proxy for bandpass information of the current system.\nAny uncorrected bandpass structure in the telescope, whether from the chromaticity in the antenna beams\nor from the signal chain, will convolve with the intrinsic foreground delay spectrum, spreading the\nforegrounds to higher delay modes and causing more contamination with the 21cm signal. Thus, one of\nthe primary goals for 21cm instrument design is to minimize the instrument's bandpass structure. While\nsky-based calibration can correct some bandpass structure, minimizing the instrument's intrinsic structure\nalleviates burden on the calibration.\nWe expect the 21cm fluctuations to be ~50 dB below the total foreground power during Cosmic Dawn,\nalthough this is dependent on the frequencies and spatial scales that will be probed. Some explanations for\nthe EDGES absorption profile predict larger 21cm fluctuations. Nevertheless, we would ideally set a\nrequirement that instrumental bandpass structure be suppressed be at the -60 dB level on the spectral scales\nthat correspond to 21cm fluctuations.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-202430822", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-202430822", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/zsgn-fe82", "primary_object": { "basename": "memo7.pdf", "url": "https://authors.library.caltech.edu/records/c3jxf-zsw71/files/memo7.pdf" }, "pub_year": "2023", "author_list": "Bowman, Judd" }, { "id": "https://authors.library.caltech.edu/records/msdqc-y5045", "eprint_id": 119271, "eprint_status": "archive", "datestamp": "2023-10-09 22:02:07", "lastmod": "2024-01-15 21:30:37", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Woody-David-P", "name": { "family": "Woody", "given": "David" } } ] }, "title": "Calculation of LWA Antenna Beams and Close Packing Effects", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo16-Woody.pdf
", "abstract": "Improving our knowledge of the LAW antenna beam pattern and the effect of nearby antennas is an\nimportant step to improving the calibration and image fidelity of the OVLWA (Owens Valley Long\nWavelength Array). Previous LWA studies carried out a MoM (method of moments) calculation of the\nbeam pattern and produced analytic approximations to the E- and H-plane beam patterns which are currently\nused for the image processing [LWA memos 175 and 178]. A MoM model has been developed using the\nGRASP and HFSS analysis programs to calculate other beam properties, such as the beam pattern in nonprinciple directions and Stokes parameters, and to explore the effect of nearby antennas and ground plate\nconfigurations.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-223418058", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-223418058", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/351y-xf54", "primary_object": { "basename": "memo16-Woody.pdf", "url": "https://authors.library.caltech.edu/records/msdqc-y5045/files/memo16-Woody.pdf" }, "pub_year": "2023", "author_list": "Woody, David" }, { "id": "https://authors.library.caltech.edu/records/rzmbw-jfz44", "eprint_id": 119232, "eprint_status": "archive", "datestamp": "2023-10-09 22:00:27", "lastmod": "2024-01-15 21:30:18", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "L." } } ] }, "title": "ADC Cross-Talk: Initial Measurements with Test Board", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo6.pdf
", "abstract": "A PCB has been constructed for testing analog-to-digital converter ICs and their input\ncircuits. It includes two Analog Devices HMDAC1511 (called devices B and D) and two Texas\nInstruments ADS5296A devices (A and C), each of which can digitize 4 signals at 200 MSa/s. They\nprovide 8b per sample and 10b per sample, respectively. For each IC type, one is connected to its\nanalog inputs using differential signaling via an ARJ45 connector, and the other is connected using\nsingle-ended (coax) signaling via four MMCX connectors and on-board baluns. The baluns use 1:2\nimpedance-ratio transformers and all signals are terminated in 100 ohms (differential) at the ADC\ndevice. The board layout allows for selecting any of several balun circuit topologies by replacing\nresistors.\nThe board design is based on that of the CASPER ADC16x250. It has the same form factor\nand its digital outputs and power use a ZDOK connector, compatible with the ROACH2 FPGA\nboard. Differences include providing bit clock and frame clock from one HMDAC1511 and one\nADS5296A (vs. bit clock only), and supporting the ADS5296A's register readback feature.\nThis report gives some initial test results. Crosstalk among the 8 signals into the two\nHMDAC1511 devices was measured. Tests involving the ADS5296A devices await necessary\nmodifications to the available FPGA code.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230213-230407858", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230213-230407858", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/r0xe-9519", "primary_object": { "basename": "memo6.pdf", "url": "https://authors.library.caltech.edu/records/rzmbw-jfz44/files/memo6.pdf" }, "pub_year": "2023", "author_list": "D'Addario, L." }, { "id": "https://authors.library.caltech.edu/records/hhfsw-txc80", "eprint_id": 119269, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:55", "lastmod": "2024-01-15 21:30:33", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Time and Synchronization for OVRO LWA352", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo14.pdf
", "abstract": "For many reasons, it is desirable for the outputs of a telescope to be labeled with the\ntimes of the observations; we call this time tagging. It requires some sort of clock, along with a\nmechanism for assigning clock readings to telescope outputs. If generating the outputs involves\ncombining multiple signals, as in a radio telescope array, and especially if that processing is\ndistributed across multiple devices, there is also a need to synchronize the timing among the\nsignals. That is, we want to ensure that the time tag assigned to an output applies in the same\nway to all signals, not just one of them or an average of them.\nThese two objectives, time tagging and synchronization, usually have very different\nrequirements for accuracy and precision. For example, for a telescope that generates outputs\nevery few seconds, time tagging with a precision of 1 s may be sufficient. But if it is combining\nsignals in a band near 1 GHz, synchronization precision must be << 1 ns. For time tagging, but\nnot for synchronization, there may be an additional requirement for accuracy with respect to an\nexternal measure of time, such as UTC; the basic requirement is with respect to time on a local\nclock (\"telescope time\"). Some telescope designs have conflated these three requirements \u2013\nsynchronization precision, time tagging precision with respect to telescope time, and time\ntagging accuracy with respect to external time \u2013 and attempted to accomplish all with a common\nimplementation, concentrating on the last item to the detriment of the others.\nWhen multiple devices must know something about time, the timing information must be\ndistributed to them from the telescope clock. The information is distributed using timing signals.\nAny timing signal can be described by two fundamental parameters, its accuracy and it\nambiguity. For example, we could use a 10 MHz tone as a timing signal. If its signal-to-noise\nratio is such a receiver can measure its phase to .01 cycle, then it has an accuracy of 1 ns; and,\nsince each cycle is indistinguishable from the next, it has an ambiguity of 100 ns. Or consider\ntransmitting periodic pulses at a rate of 1 per second (1 PPS, which is a traditional choice in\nradio astronomy, introduced in VLBI practice more than 50 years ago). If its SNR is such that a\nreceiver can measure the rising edge to 10 ns, then that is its accuracy; its ambiguity is 1 s. Or\nconsider transmitting a 64b number that is proportional to time with its LSB representing 1 ns.\nIts ambiguity is 584 years. In principle its accuracy is 1 ns, but in practice it is difficult to build a\ndigital receiver that can measure the number's arrival time to 1 ns, and to build a digital network\nwhose latency is stable and known to 1 ns. The point is that there are practical limits to the\nambiguity-to-accuracy ratio that can be achieved with a single signal. To achieve a higher ratio,\nmultiple timing signals can be used in a hierarchy. A fast signal is used to obtain the required\naccuracy, but with low ambiguity; a slower signal then has just enough accuracy to resolve the\nambiguity of the fast signal, but larger ambiguity. We continue in this way with additional\nsignals until the desired ambiguity is achieved, retaining the first signal's accuracy. The key is\nthat each signal must resolve the ambiguity of its predecessor, and of course all signals must be\nconsistent with each other (all derived from the same clock). Some telescopes have been\ndesigned with fast and slow timing signals but without paying attention to these principles.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-222841553", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-222841553", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/ve46-gx54", "primary_object": { "basename": "memo14.pdf", "url": "https://authors.library.caltech.edu/records/hhfsw-txc80/files/memo14.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/28e1j-z4n82", "eprint_id": 119270, "eprint_status": "archive", "datestamp": "2023-10-09 22:02:01", "lastmod": "2024-01-15 21:30:35", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "LWA352 Digitizers: Design Concept", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo15.pdf
", "abstract": "The first stage of digital signal processing for LWA352 will use SNAP2 FPGA boards\n[1]. Each SNAP2 is expected to be capable of handling at least 64 LWA signals sampled at\nabout 200 MHz, but it is a challenge to get that many digitized signals into the board. Our\ndesign will achieve this by using both of the SNAP2's FPGA Mezzanine Card high-pin-count\n(FMC-HPC) connectors to accommodate daughter cards carrying the analog-to-digital\nconverters. It is the design of those Digitizer Boards that we discuss here..\nII. CONSTRAINTS\nAnalog signal processing for LWA352 will be accomplished in a separate rack from the\ndigital processing, and each signal will be connected to the digital rack on a coaxial cable.\nAvailable ADC integrated circuits for our sampling rate have differential inputs, so baluns is\nrequired on the Digitizer Boards.\nA survey of available ADC ICs identified only two devices having at least 4 channels and\nat least 8 bits of resolution at 200 MHz sampling: the Analog Devices HMCAD1511 and the\nTexas Instruments ADS5296A. The HMCAD1511 has been used in some Casper ADC boards\n[2], including those of the first- and second-phase implementations of LWA-OVRO. We have\nselected the ADS5296A because it claims better isolation among channels, has finer resolution\n(10b), and has additional useful features (including synchonization among devices and register\nreadback).\nThe FMC interface is a VITA/ANSI industry standard [3] that specifies the connectors in\nsome detail, including functional assignments of pins [4]. The SNAP2 closely conforms to the\nstandard pinout, although some pins are unconnected. The standard also specifies the form\nfactor and other details of the daughter (\"mezzanine\") cards [5], making them rather small; all\nare 69 mm wide and the longest is 84 mm. This is not enough space for a large number of coax\nconnectors, balun transformers, and ADC ICs. To get 64 signals into the SNAP2, we need 32\nper FMC connector, requiring 8 of the ADS5296A quad-ADC devices. We will use a nonstandard form factor, but the width is still constrained by the spacing of the connectors on the\nSNAP2 board (Figure 1) to a maximum of 76 mm. The SNAP2 is designed to fit a standard\nFMC card that is 76.5 mm long, but ours will have to be longer, so they will extend over the\nfront edge of the SNAP2.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-223113634", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-223113634", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/0903-2x44", "primary_object": { "basename": "memo15.pdf", "url": "https://authors.library.caltech.edu/records/28e1j-z4n82/files/memo15.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/3k1hq-s0640", "eprint_id": 119267, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:44", "lastmod": "2024-01-15 21:30:29", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Optical Link Tests", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo12.pdf
", "abstract": "This report describes measurements to characterize an RF-over-fiber link using a\nYiGuDian laser diode (LD, Part Number GLD-PSA2-D3160B-2GR, Serial Number 180516-002) and a YiGuDian photodiode (PD, PN GPD-PSA1-55BR, SN 180511-002). The objective is\nto characterize the phototonic components alone, without any other circuitry. It complements\nand extends the results in [1], which were measured on the same units. For RF tests, the laser\ndiode was driven directly from a 50-ohm source, and the photodiode was connected directly to a\n50 ohm load. DC bias was supplied through high RF impedances. This means that the source\nand load were highly mismatched, since the RF impedance of the laser is 4 to 5 ohms and that of\nthe photodiode is many thousands of ohms. However, all measurements were below 100 MHz\nand connections were via wires no more than 2 cm long.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-214424637", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-214424637", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/drym-g468", "primary_object": { "basename": "memo12.pdf", "url": "https://authors.library.caltech.edu/records/3k1hq-s0640/files/memo12.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/x3xrg-krq84", "eprint_id": 119261, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:22", "lastmod": "2024-01-15 21:30:21", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Filter Designs for Next-Generation Analog Receivers", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo8.pdf
", "abstract": "A preliminary design for bandpass filters in the next-generation analog receivers of OVRO-LWA is described in [3] and was presented at the Preliminary Design Review of June 2019. The plan was to provide three remotely-selectable filters, all of which are intended to suppress high-power RFI in the bands below 20 MHz and above 88 MHz. One filter (\"Wide\") extends the bandwidth as much as practical on each end, while accepting some risk that observations will be RFI-contaminated or that gain and SNR will have to be reduced to avoid intermodulation. Another (\"Safe\") is intended to have low risk of RFI contamination and to maximize sensitivity in the center of the observing band, while accepting lower total bandwidth. The third (\"Smooth\") is designed to have a maximally-smooth bandpass, requiring still smaller total bandwidth to achieve adequate RFI suppression. The designs included selection of specific, available components and detailed simulations of performance, taking into account non-ideal behavior of practical inductors and parasitic effects of PC board layout. Since then, additional studies have been done via simulation of the performance of the selected filters in the measured RFI environment at OVRO, and some adjustments to the cutoff frequencies have been explored. This is partly in response to a suggestion in the PDR report of the Technical Advisory Committee [2] that frequency coverage be extended to lower frequencies than had previously been considered. This has led to changes in the filter selection topology and\nin the details of the filter responses. This memo describes the current design (\"ARX filters revision 2\") and the considerations that led to it. The new designs include specific component selection and detailed simulation, and they have been implemented on a test printed circuit board. Results of simulations and testing are reported here.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-202832954", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-202832954", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/351s-5q40", "primary_object": { "basename": "memo8.pdf", "url": "https://authors.library.caltech.edu/records/x3xrg-krq84/files/memo8.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/dm0zq-mdb45", "eprint_id": 119264, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:33", "lastmod": "2024-01-15 21:30:25", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "FMC Daughter Board Stacking on SNAP2: Signal Integrity Tests For LWA352 Digitizers", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo10.pdf
", "abstract": "The digital processing design for LWA352 includes use of SNAP2 FPGA boards [1] for the initial processing stage, including the F engine and cosmic ray detection. Calculations and benchmarking show [2] that the Xilinx Ultrascale XCKU115FLVF1924 FPGA on the SNAP2 board has sufficient processing and I/O capacity to handle at least 64 separate signals. However, creating enough digitizer channels to accept 64 analog signals and to deliver their quantized samples to the SNAP2 is challenging. ADC chips capable of nearly 200 MHz sampling rate can handle at most 4 signals each, so 16 such chips are needed. On the analog side, connectors for delivering those signals to the ADCs necessarily occupy significant PCB area, especially since they must be kept well separated to avoid cross-talk. For available ADC chips, the digitized output is provided via multiple high-speed LVDS streams. For such signals, the most suitable digital interface from digitizer boards to the SNAP2 is the FPGA Mezzanine Card (FMC) connector. The SNAP2 has two high-pin-count FMC connectors, each with 400 pins. We have verified that each of these has sufficient LVDS pairs routed to the FPGA to support 32 signals. The FMC concept is that a daughter board (\"mezzanine card\") plugs into the mother board (\"carrier card\"). Figure 1 includes a photograph of a SNAP2 board showing its two FMC connectors with no mezzanine cards, and with a card plugged into the \"left\" connector. That mezzanine card (from the Chinese Institute of Automation, IoA) has size 69.0 x 84.2 mm and fits within the space allowed for it on the SNAP2. There are standard form factors for FMC-compliant mezzanine cards, but we are designing our own digitizer boards and we are not constrained to use those form factors. Nevertheless, the SNAP2 layout limits the width of FMC cards to 76 mm if both connectors are used. The length can be considerably larger than that of the card shown in Fig 1 if we are willing to have it cantilevered beyond the edge of the SNAP2. We will do that for our boards. With these constraints, we find that we are unable to handle more than 16 signals on a single digitizer board, even when it is constructed as a 10-layer board. A preliminary rendering of such a board is shown in Figure 2. It uses 16 MMCX coax connectors for its analog inputs, and 4 Texas Instruments ADS5296A quad-ADC chips. To deliver 32 digitized signals to one FMC connector, we plan to stack two such boards, with the upper and lower boards using different FMC pins for their output LVDS streams and clocks but common pins for power and control. The lower board requires an FMC carrier-card connector on its upper side and an FMC mezzanine-card connector on its lower side, with selected pins connected directly from one side to the other. A concern with this arrangement is whether the integrity of the high-speed LVDS signals can be maintained across two mated FMC connector pairs and through the lower board. This report describes tests that demonstrate satisfactory performance in that situation.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-212556098", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-212556098", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/fr0g-k578", "primary_object": { "basename": "memo10.pdf", "url": "https://authors.library.caltech.edu/records/dm0zq-mdb45/files/memo10.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/7yhtp-vk519", "eprint_id": 119266, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:39", "lastmod": "2024-01-15 21:30:27", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Requirement for Maximum Intermodulation-Produced RFI", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo11.pdf
", "abstract": "The LWA is subject to strong RFI outside our desired observing band of 20-85 MHz, including FM radio at 88-108 MHz and HF radio at 3-20 MHz. FM radio signals are primarily\nlocal and nearly line-of-sight; the power level is stable. The HF radio signals are primarily distant and arrive by reflections from the ionosphere; the power level is highly variable. The out-of-band signals are suppressed by filtering in the analog signal path so that by the time the entire signal is digitized it is well within the dynamic range of the digitizer [1]. However, non-linearity anywhere in the analog signal path can produce intermodulation among the RFI signals such that the intermodulation products fall within the observing band; these cannot be suppressed by filtering. Therefore non-linearity must be small enough to keep the inband products sufficiently small. What is sufficiently small? This memo proposes a design criterion to achieve an acceptable level.", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-214113131", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-214113131", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/kmgv-7423", "primary_object": { "basename": "memo11.pdf", "url": "https://authors.library.caltech.edu/records/7yhtp-vk519/files/memo11.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/1h4y9-gbn42", "eprint_id": 119262, "eprint_status": "archive", "datestamp": "2023-10-09 22:01:27", "lastmod": "2024-01-15 21:30:23", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry R." } } ] }, "title": "Next Generation Analog Receiver Design: Amplifier Selection", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo9.pdf
", "abstract": "This memo discusses design considerations for the new Analog Receivers (ARXs), focusing on the choice of amplifiers. The main concern is avoiding intermodulation from the very strong RFI that accompanies the signal received by the ARX from the antenna. The strongest RFI is outside observing band, but there is little filtering ahead of the ARX. Measurements have shown that the total RFI power is nearly 1000 times larger than the total power in the observing band [4].", "date": "2023-02-14", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230214-203235708", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230214-203235708", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/h5yy-4r03", "primary_object": { "basename": "memo9.pdf", "url": "https://authors.library.caltech.edu/records/1h4y9-gbn42/files/memo9.pdf" }, "pub_year": "2023", "author_list": "D'Addario, Larry R." }, { "id": "https://authors.library.caltech.edu/records/pp9ff-v6692", "eprint_id": 119231, "eprint_status": "archive", "datestamp": "2023-10-09 21:23:59", "lastmod": "2024-01-15 21:30:16", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "L." } } ] }, "title": "Spectra of OVRO-LWA signals at correlator: predicted vs. observed", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo5.pdf
", "abstract": "The variation with frequency of the power spectral density (PSD) of OVRO-LWA signals is significantly different than expected within the 25-85 MHz observing band, both for the core antennas (coax-connected) and the expansion antennas (fiber-connected). We observe that the peak of the spectrum is at 33 MHz and the minimum is at 85 MHz; this much is as expected. At the antenna (front end output), the ratio of PSDs at these frequencies is predicted to be 8.1 dB. At the correlator, it should be the same for fiber-connected antennas, and it should be 9.6 to 18.2 dB for coax-connected antennas, depending on cable length. We actually observe a\nmuch steeper dropoff. The range is 11.1 to 17.7 dB for fiber-connected antennas (median 14.7 dB) and 11.4 to 20.7 dB for coax-connected antennas (median 18.6 dB).", "date": "2023-02-13", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230213-225911200", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230213-225911200", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/8wws-ap55", "primary_object": { "basename": "memo5.pdf", "url": "https://authors.library.caltech.edu/records/pp9ff-v6692/files/memo5.pdf" }, "pub_year": "2023", "author_list": "D'Addario, L." }, { "id": "https://authors.library.caltech.edu/records/rr40s-65d46", "eprint_id": 119223, "eprint_status": "archive", "datestamp": "2023-10-09 21:23:42", "lastmod": "2024-01-15 21:30:10", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "L." } }, { "id": "Hodges-Mark-W", "name": { "family": "Hodges", "given": "Mark" } } ] }, "title": "RFI Environment at the OVRO LWA: Quantitative Measurements", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo2.pdf
", "abstract": "Measurements of the power spectral density of signals received by a few selected OVRO LWA antennas were collected for at least 24 hours over the frequency range 0 to 165 MHz. The objective was to quantify the RFI environment, concentrating primarily on the signals outside the target observing band of 25 to 85 MHz. Those out-of-band signals are subject to suppression by filtering. Significant filtering is practical only after the signals are delivered to the processing shelter, so these results can be used to set the dynamic range requirements for the RF-over-fiber links from outer antennas and for the pre-filtering analog signal processing at the shelter, as well as the amount of filtering needed to keep the signals within the dynamic range of the digitizers. It is found that the total power below 20 MHz (HF communication) is highly variable with peaks about 16 dB above the total power in the observing band, and that the total power above 88 MHz (primarily FM radio) is very stable at about 29 dB above the minimum power in the observing band. Sporadic in-band RFI is also seen.", "date": "2023-02-13", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230212-023120138", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230212-023120138", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/z6b6-7k39", "primary_object": { "basename": "memo2.pdf", "url": "https://authors.library.caltech.edu/records/rr40s-65d46/files/memo2.pdf" }, "pub_year": "2023", "author_list": "D'Addario, L. and Hodges, Mark" }, { "id": "https://authors.library.caltech.edu/records/t32q2-r7g25", "eprint_id": 119230, "eprint_status": "archive", "datestamp": "2023-10-09 21:23:53", "lastmod": "2024-01-15 21:30:14", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "L." } } ] }, "title": "Effective Dynamic Range of Digitizers in the OVRO-LWA Telescope", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo4.pdf
", "abstract": "In radio astronomy, very coarse signal quantization is acceptable because of the noise-like nature of the signals [1]. Thus, 2-level (1 bit) quantization was used in early spectrometers and VLBI, 3-level quantization was used in the original VLA, 4-level (2 bit) is still used in VLBI, and 8-level (3 bit) quantization is used in wide-bandwidth modes of the current JVLA and ALMA. This limits quantization noise to a small fraction of the system noise, provided that the signal level to the digitizer is optimally set [1]. However, additional resolution is sometimes needed, for three reasons. First, a wide-bandwidth receiving system may have gain and noise temperature that vary considerably with frequency, making the spectrum at the digitizer non-flat. This requires a digitizer whose voltage range accommodates a higher total power than if the spectrum were flat, while still providing enough resolution at the weakest-signal frequency. Consequently, more quantization levels (bits) are needed. Second, the desired signal (system noise, including instrumental and astronomical noise) may be accompanied by undesired signals (\"RFI\"). If the total power in RFI is comparable to or greater than the total power in the desired signal, then the digitizer voltage range must be even larger to avoid saturation when the RFI is present. Third, the system noise power and receiver gain may vary with time, making it difficult to maintain the optimum level at the digitizer input. In this memo, the implications for the OVRO LWA telescope are investigated. The telescope has a desired frequency range of 20 to 85 MHz, and the over that range the signal from one antenna has a significant spectral dynamic range because of both the sky brightness variation and the antenna gain variation. Outside that range, there is substantial RFI due to FM radio (88-108 MHz) and HF communication signals reflected from the ionosphere (5-20 MHz, mostly). The out-of-band RFI can be suppressed by filtering, so this study is partly for the purpose of determining how much suppression is needed.", "date": "2023-02-13", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230213-225325158", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230213-225325158", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/k0q2-xb59", "primary_object": { "basename": "memo4.pdf", "url": "https://authors.library.caltech.edu/records/t32q2-r7g25/files/memo4.pdf" }, "pub_year": "2023", "author_list": "D'Addario, L." }, { "id": "https://authors.library.caltech.edu/records/m1am6-51k11", "eprint_id": 119224, "eprint_status": "archive", "datestamp": "2023-10-09 21:23:48", "lastmod": "2024-01-15 21:30:12", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Atwater-Jackson", "name": { "family": "Atwater", "given": "Jackson" } }, { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "Larry" } }, { "id": "Kocz-Jonathon", "name": { "family": "Kocz", "given": "Jonathon" }, "orcid": "0000-0003-0249-7586" } ] }, "title": "ADC Crosstalk Measurements with SNAP for OVRO-LWA", "ispublished": "unpub", "full_text_status": "public", "note": "Accepted Version - memo3.pdf
", "abstract": "The LWA (Long-Wavelength Array), located at Owens Valley Radio Observatory, is a powerful and sensitive radio telescope. OVRO-LWA needs very good signal transmission with minimal spurious emissions carried through its signal chain. \n\nThe telescope receives analog radio signals from space, then interprets them as digital data that can be computationally analyzed to gain a better understanding of what that data means. A high-level description of the flow of information in the LWA is as follows: \n\nAnalog receiver \u2192 analog-to-digital conversion (ADC) \u2192 short-timescale FPGA processing \u2192 long-timescale GPU processing \n\nIn order to minimize unwanted effects, some parts of the signal chain are being redesigned. This includes possible changes in the ADCs employed, the FPGA used, or the circuitry linking the two. A variety of options are available for the new hardware, including several boards from the CASPER1 collaboration. Currently, the LWA uses CASPER ADC16x250-8 RJ45 rev 1 boards with HMCAD1511 ADC chips. A different CASPER board, or a new combination of ADC and FPGA hardware from multiple platforms, may be used. Among the candidate replacement boards is SNAP2 (Smart Network ADC Processor). In order to determine the viability of retooling the SNAP board for this purpose, the performance characteristics of its ADC hardware have been tested.", "date": "2023-02-13", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20230212-023805143", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230212-023805143", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" }, { "id": "Owens-Valley-Radio-Observatory-Memos" } ] }, "doi": "10.7907/pn4x-gn76", "primary_object": { "basename": "memo3.pdf", "url": "https://authors.library.caltech.edu/records/m1am6-51k11/files/memo3.pdf" }, "pub_year": "2023", "author_list": "Atwater, Jackson; D'Addario, Larry; et el." }, { "id": "https://authors.library.caltech.edu/records/s031f-n3r08", "eprint_id": 97315, "eprint_status": "archive", "datestamp": "2023-08-19 16:48:06", "lastmod": "2024-01-14 21:50:27", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Hallinan-G", "name": { "family": "Hallinan", "given": "G." }, "orcid": "0000-0002-7083-4049" }, { "id": "Ravi-Vikram", "name": { "family": "Ravi", "given": "V." }, "orcid": "0000-0002-7252-5485" }, { "id": "Weinreb-S", "name": { "family": "Weinreb", "given": "S." }, "orcid": "0000-0002-9353-6204" }, { "id": "Kocz-Jonathon", "name": { "family": "Kocz", "given": "J." }, "orcid": "0000-0003-0249-7586" }, { "id": "Huang-Y", "name": { "family": "Huang", "given": "Y." } }, { "id": "Woody-David-P", "name": { "family": "Woody", "given": "D. P." } }, { "id": "Lamb-James-W", "name": { "family": "Lamb", "given": "J. W." }, "orcid": "0000-0002-5959-1285" }, { "id": "D'Addario-Larry-R", "name": { "family": "D'Addario", "given": "L." } }, { "id": "Catha-Morgan", "name": { "family": "Catha", "given": "M." } }, { "id": "Shi-Jun", "name": { "family": "Shi", "given": "J." }, "orcid": "0000-0003-1647-7762" }, { "id": "Law-Casey-J", "name": { "family": "Law", "given": "C. J." }, "orcid": "0000-0002-4119-9963" }, { "id": "Kulkarni-S-R", "name": { "family": "Kulkarni", "given": "S. R." }, "orcid": "0000-0001-5390-8563" }, { "id": "Phinney-E-S", "name": { "family": "Phinney", "given": "E. S." }, "orcid": "0000-0002-9656-4032" }, { "id": "Eastwood-Michael-W", "name": { "family": "Eastwood", "given": "M. W." }, "orcid": "0000-0002-4731-6083" }, { "id": "Bouman-K-L", "name": { "family": "Bouman", "given": "K. L." }, "orcid": "0000-0003-0077-4367" }, { "id": "McLaughlin-Maura-A", "name": { "family": "McLaughlin", "given": "M. A." }, "orcid": "0000-0001-7697-7422" }, { "id": "Ransom-Scott-M", "name": { "family": "Ransom", "given": "S. M." }, "orcid": "0000-0001-5799-9714" }, { "id": "Siemens-Xavier", "name": { "family": "Siemens", "given": "X." }, "orcid": "0000-0002-7778-2990" }, { "id": "Cordes-James-M", "name": { "family": "Cordes", "given": "J. M." }, "orcid": "0000-0002-4049-1882" }, { "id": "Lynch-Ryan-S", "name": { "family": "Lynch", "given": "R. S." }, "orcid": "0000-0001-5229-7430" }, { "id": "Kaplan-David-L", "name": { "family": "Kaplan", "given": "D. L." }, "orcid": "0000-0001-6295-2881" }, { "id": "Chatterjee-Shami", "name": { "family": "Chatterjee", "given": "S." }, "orcid": "0000-0002-2878-1502" }, { "id": "Lazio-T-Joseph-W", "name": { "family": "Lazio", "given": "J." }, "orcid": "0000-0002-3873-5497" }, { "id": "Brazier-Adam", "name": { "family": "Brazier", "given": "A." }, "orcid": "0000-0001-6341-7178" }, { "id": "Bhatnagar-S", "name": { "family": "Bhatnagar", "given": "S." } }, { "id": "Myers-Steven-Theodore", "name": { "family": "Myers", "given": "S. T." } }, { "id": "Walter-Fabian", "name": { "family": "Walter", "given": "F." }, "orcid": "0000-0003-4793-7880" }, { "id": "Gaensler-Bryan-M", "name": { "family": "Gaensler", "given": "B. M." }, "orcid": "0000-0002-3382-9558" } ] }, "title": "The DSA-2000 - A Radio Survey Camera", "ispublished": "unpub", "full_text_status": "public", "note": "Submitted - 1907.07648.pdf
", "abstract": "We present the DSA-2000: a world-leading radio survey telescope and multi-messenger discovery engine for the next decade. The array will be the first true radio camera, outputting science-ready image data over the 0.7 - 2 GHz frequency range with a spatial resolution of 3.5 arcsec. With 2000 x 5 m dishes, the DSA-2000 will have an equivalent point-source sensitivity to SKA1-mid, but with ten times the survey speed. The DSA-2000 is envisaged as an all-sky survey instrument complementary to the ngVLA, and as a counterpart to the LSST (optical), SPHEREx (near-infrared) and SRG/eROSITA (X-ray) all-sky surveys. Over a five-year prime phase, the DSA-2000 will image the entire sky above declination -30 degrees every four months, detecting > 1 unique billion radio sources in a combined full-Stokes sky map with 500 nJy/beam rms noise. This all-sky survey will be complemented by intermediate and deep surveys, as well as spectral and polarization image cubes. The array will be a cornerstone for multi-messenger science, serving as the principal instrument for the US pulsar timing array community, and by searching for radio afterglows of compact object mergers detected by LIGO and Virgo. The array will simultaneously detect and localize ~10,000 fast radio bursts each year, realizing their ultimate use as a cosmological tool. The DSA-2000 will be proposed to the NSF Mid-Scale Research Infrastructure-2 program with a view to first light in 2026.", "date": "2019-07-22", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20190722-100036103", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190722-100036103", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Astronomy-Department" }, { "id": "Division-of-Geological-and-Planetary-Sciences" }, { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.48550/arXiv.1907.07648", "primary_object": { "basename": "1907.07648.pdf", "url": "https://authors.library.caltech.edu/records/s031f-n3r08/files/1907.07648.pdf" }, "pub_year": "2019", "author_list": "Hallinan, G.; Ravi, V.; et el." }, { "id": "https://authors.library.caltech.edu/records/rajb3-ydp06", "eprint_id": 47221, "eprint_status": "archive", "datestamp": "2023-08-19 04:16:07", "lastmod": "2024-01-13 16:06:41", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Read-R-B", "name": { "family": "Read", "given": "Richard Bradley" } } ] }, "title": "Accurate Measurement of the Declinations of Radio Sources", "ispublished": "unpub", "full_text_status": "public", "note": "The author wishes to take this opportunity to thank the following: T. A.\nMatthews, for many helpful discussions on the measurement of the positions of radio sources and the problems involved in identifying them. R. Griffin, for making available the very accurate measurements he made of the optical positions of identified radio sources. P. Maltby and A. Moffet, for making available the results of their angular size measurements well in advance of publication. The\ngraduate students and observatory staff members who assisted in the making of the observations and in the reduction of the data.\nThe material for this paper formed a part of the author's thesis. The research\nwas supported by the Office of Naval Research under Contract Nonr 220(19).\n\nAccepted Version - 382084.pdf
", "abstract": "The two 90-foot steerable paraboloids of the Owens Valley Radio Observatory\nwere used as a two-element interferometer at 960 Mc/s with various separations\nalong a north-south baseline to measure accurately the declinations of a number of\nradio sources, most of which were of small diameter. The measured values of declination\nare tabulated for 110 sources with right ascensions between 0 hours and\n14 hours 10 minutes. The standard errors of the measured values range from \u00b1 2.6\nseconds of arc to \u00b1 46 seconds of arc with an average of \u00b1 13 seconds of arc. A\ndiscussion of the sources of error is included.", "date": "2014-07-15", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140715-103952810", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140715-103952810", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/7hw7-ay35", "primary_object": { "basename": "382084.pdf", "url": "https://authors.library.caltech.edu/records/rajb3-ydp06/files/382084.pdf" }, "pub_year": "2014", "author_list": "Read, Richard Bradley" }, { "id": "https://authors.library.caltech.edu/records/y8mqg-kd226", "eprint_id": 47106, "eprint_status": "archive", "datestamp": "2023-08-19 03:24:01", "lastmod": "2024-01-13 16:06:33", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bolton-J-G", "name": { "family": "Bolton", "given": "J. G." } } ] }, "title": "The Discrete Sources of Cosmic Radio Emission", "ispublished": "unpub", "full_text_status": "public", "note": "Introductory talk at the session on discrete sources at the U.R.S.I. General Assembly, London, September, 1960.\n\nI am indebted to the staff and student members of the California\nInstitute of Technology Radio Observatory for much of the unpublished\ndata used in this paper. The work of this observatory is supported by\nthe United States Office of Naval Research under Contract Nonr 220(19).\nI wish to thank Dr. Rudolph Minkowski for contributing optical data and\nfor discussion on many points.\n\nAccepted Version - The_discrete_sources_of_cosmic_Radio_Emission.pdf
", "abstract": "One of the principal problems in the radio astronomy of the\ndiscrete sources is their identification with visible objects.\nIdentification is necessary in . most instances to determine the distance\nof a source and thus its intrinsic luminosity. It is of assistance\nin deciding the probable mechanism for the radio emission.\nIdentification of a reasonable sample of radio sources should be made\nprior to speculations from statistical studies of the radio sources\nas a class.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-103849543", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-103849543", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/01hm-wr42", "primary_object": { "basename": "The_discrete_sources_of_cosmic_Radio_Emission.pdf", "url": "https://authors.library.caltech.edu/records/y8mqg-kd226/files/The_discrete_sources_of_cosmic_Radio_Emission.pdf" }, "pub_year": "2014", "author_list": "Bolton, J. G." }, { "id": "https://authors.library.caltech.edu/records/6jt73-abd65", "eprint_id": 47099, "eprint_status": "archive", "datestamp": "2023-08-19 03:40:39", "lastmod": "2024-01-13 16:06:29", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Moffet-A-T", "name": { "family": "Moffet", "given": "Alan T." } } ] }, "title": "Brightness Distribution in Discrete Radio Sources I. Observations with an East-West Interferometer", "ispublished": "unpub", "full_text_status": "public", "note": "The material in this paper forms a portion of a thesis submitted\nto the Faculty of the California Institute of Technology in partial fulfillment\nof the requirements for the Ph.D. degree. The author has held a\nNational Science Foundation Predoctoral Fellowship during the cource of\nthis work. The assistance of D. Morris, V. Radhakrishnan, and D. E. Harris\nin taking the observations is gratefully acknowledged, as are the discussions\nand criticisms of P. Maltby, T. A. Matthews, R. B. Leighton, G. J.\nStanley, and J. G. Bolton. Thanks are due to Matthews and to R. W. Wilson\nfor making available the results of their observations in advance of publication.\nThe program in radio astronomy at the California Institute of Technology\nis supported by the United States Office of Naval Research under\nContract Nonr 220(19).\n\nAccepted Version - Brightness_distribution_in_discrete_radio_sources_I._Observations_with_an_east-west_interferometer.pdf
", "abstract": "The Caltech variable baseline interferometer has been used in a program\nof brightness distribution measurements on 195 discrete radio sources at a wave length of 31.3 cm. This paper reports measurements, made with an east- west\ninterferometer baseline, of the complex visibility functions of 127 sources.\nThe amplitude and phase of the visibility functions were measured at transit\nwith antenna spacings of 195\u03bb, 389\u03bb, 779\u03bb and 1557\u03bb. Using these same basic\nspacings, and by observing at large hour angles, the visibility amplitude was\nmeasured at ten other effective spacings between 126\u03bb and 1363\u03bb. Not all sources\nare observed at all spacings. The data are presented in tabular form, and\ngraphs of the visibility amplitude as a function of antenna spacing are given\nfor 51 of the more interesting sources. The interpretation of these data in\nterms of source brightness distributions will be given in another paper.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-095442913", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-095442913", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" }, { "agency": "National Science Foundation Predoctoral Fellowship" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/czpy-yr69", "primary_object": { "basename": "Brightness_distribution_in_discrete_radio_sources_I._Observations_with_an_east-west_interferometer.pdf", "url": "https://authors.library.caltech.edu/records/6jt73-abd65/files/Brightness_distribution_in_discrete_radio_sources_I._Observations_with_an_east-west_interferometer.pdf" }, "pub_year": "2014", "author_list": "Moffet, Alan T." }, { "id": "https://authors.library.caltech.edu/records/0nhmd-26d46", "eprint_id": 47091, "eprint_status": "archive", "datestamp": "2023-08-19 03:23:50", "lastmod": "2024-01-13 16:06:27", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kellermann-K-I", "name": { "family": "Kellermann", "given": "K. I." }, "orcid": "0000-0002-0093-4917" }, { "id": "Harris-D-E", "name": { "family": "Harris", "given": "D. E." } } ] }, "title": "7.960 MC/S Observations of Radio Sources in the Sydney Catalogue", "ispublished": "unpub", "full_text_status": "public", "note": "We wish to express our appreciation to Drs. Mills, Slee,\nand Hill who kindly provided us with the latest results of their\nsurvey in advance of publication . We are grateful to Professor\nJ . G. Bolton for his constant guidance throughout the course of\nthis program . We would also like to thank Dr. D. Morris and Mr.\nJ. F . Bartlett for their assistance during the observations, Mr.\nA. T. Moffet for the use of unpublished results, and Mr . V.\nRadhakrishnan for his comments on the manuscript . This work was\nperformed under U. S . Office of Naval Research Contract Nonr 220(19).\n\nAccepted Version - 960_MCS_observations_of_radio_sources_in_the_Sydney_catalogue.pdf
", "abstract": "During March and September 1960, observations were made\nwith the Caltech interferometer of 739 sources listed in the\ntwo catalogues of Mills, Slee and Hill^1,^2. The primary purpose\nof the investigation was to provide this observatory\nwith a 960 Mc/s \"finding list\" for future measurements of\nsource sizes and precise positions.\n\nThe area covered in these observations was:\n0: -50\u00b0 to -20\u00b0 a: 17 to 5 hours\no: -20\u00b0 to +10\u00b0 a: O to 24 hours.\n\nIn general, the observations were restricted to sources in the\nMSH catalogues whose flux density at 86 Mc/s was greater than\n15 x l0^(-26) watts m^-2 (c/s)^-l. All sources down to this level\nwere examined with the exception of those in the region 18h to\n24h, between o^o and -10\u00b0 .\nMost sources were observed near transit for at least four\nor five minutes at the position given in the Sydney catalogues.\nThis allowed us to observe one 10-degree declination zone each\nnight. The flux density of each source was measured relative to\nthe standard source Hydra A ( 09-14), which was observed each\nnight when possible. When Hydra A was not available, 22-11 was used as a secondary calibrator. All observations were made at\nnight to avoid effects of solar radiation.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-090040103", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-090040103", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/nsy9-9s64", "primary_object": { "basename": "960_MCS_observations_of_radio_sources_in_the_Sydney_catalogue.pdf", "url": "https://authors.library.caltech.edu/records/0nhmd-26d46/files/960_MCS_observations_of_radio_sources_in_the_Sydney_catalogue.pdf" }, "pub_year": "2014", "author_list": "Kellermann, K. I. and Harris, D. E." }, { "id": "https://authors.library.caltech.edu/records/9btvw-aja20", "eprint_id": 47105, "eprint_status": "archive", "datestamp": "2023-08-19 03:23:56", "lastmod": "2023-10-26 20:18:58", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harris-D-E", "name": { "family": "Harris", "given": "D. E." } }, { "id": "Roberts-J-A", "name": { "family": "Roberts", "given": "J. A." } } ] }, "title": "Radio Source Measurements at 960 MC/S", "ispublished": "unpub", "full_text_status": "public", "note": "This investigation formed part of the program of the\nOwens Valley Radio Observatory and was carried out under U.S.\nOffice of Naval Research Contract Nonr 220(19). We are grateful\nto Professor J. G. Bolton for his guidance and encouragement in\nthis work; to Mr. G. J. Stanley, who was responsible for the\nreceiving equipment; to Mr. B. G. Clark for his help in examining\nthe Schmidt plates; and to our several colleagues for their\nassistance in the observational program.\n\nSubmitted - Radio_source_measurements_at_960_MCS.pdf
", "abstract": "The major surveys of radio sources made at meter wavelengths\nhave shown a disquieting lack of agreement, and an\nindependent study of these sources using as simple an antenna\nas possible seems to be desirable. As a partial step in this\ndirection, we report here a study of 106 radio sources made\nwith one of the equatorially-mounted 90-foot paraboloids of\nthe Owens Valley Radio Observatory. This investigation was\nmade at a frequency of 960 Mc/s.\nThe primary result of the study is a reliable catalog of\nsources which will be used as a 'finding list' for precise position\nmeasurements which are currently being undertaken with the\ntwo antennas operating as an interferometer. In addition,\nhowever, the results provide valuable information on the spectra\nof the sources, and have also been used in a search for optical\ncounterparts to the sources.\nNinety of the objects observed were taken from the Third\nCambridge Survey (3C), which was kindly made available to us by\nthe authors prior to publication. The remaining 16 objects in\nthe present list were either taken from other catalogs or were\ndiscovered in the course of the present investigation.\nThe equipment is briefly described in Section II, and in\nSections III and IV the methods of determining the position and\nintensity of the sources are outlined. In Section V suggested\noptical identifications are discussed, while Section VI is\ndevoted to a consideration of the spectra of the sources. The\npositions, intensities, spectral indices, and other pertinent\ndata for the 106 sources are collected in Table I.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-103025594", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-103025594", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/ytt8-a898", "primary_object": { "basename": "Radio_source_measurements_at_960_MCS.pdf", "url": "https://authors.library.caltech.edu/records/9btvw-aja20/files/Radio_source_measurements_at_960_MCS.pdf" }, "pub_year": "2014", "author_list": "Harris, D. E. and Roberts, J. A." }, { "id": "https://authors.library.caltech.edu/records/adpmr-svm06", "eprint_id": 47108, "eprint_status": "archive", "datestamp": "2023-08-19 03:40:49", "lastmod": "2024-01-13 16:06:35", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Harris-D-E", "name": { "family": "Harris", "given": "D. E." } } ] }, "title": "The Radio Spectrum of Supernova Remnants", "ispublished": "unpub", "full_text_status": "public", "note": "It is a pleasure to thank Gordon Stanley for his critical reading\nof this manuscript and his many helpful suggestions. I would also like\nto express my gratitude to the staff and graduate students for their\nhelp in obtaining the observations and to R. Minkowski for his comments\non the optical features of the sources and for the deep red plates reproduced in Appendix III. Much of this paper would have been impossible\nwithout access to the Manchester work on the Cygnus Loop and I am indebted\nto D. Mathewson for sending that in advance of publication.\nSpecial thanks are also due G. Westerhout for the 400 Mc/s flux densities\nof several sources. Finally, I would like to acknowledge the Consultants\nBureau Inc., who kindly provided pre-publication translations of\nShklovsky's papers. The observations reported here were carried out\nunder Office of Naval Research Contract Nonr 220(19).\n\nAccepted Version - The_radio_spectrum_of_supernova_remnants.pdf
", "abstract": "960 Mc/s observations of thirteen galactic sources generally\nassumed to be supernova remnants, are coupled with previous observations at other frequencies to derive spectral indices. Although\nseveral values of spectral index are found in the neighborhood\nof zero, arguments are presented that free-free transitions\nare not the primary cause of the radio emission.\nAn interpretation of the relatively large range of spectral\nindices is suggested on the basis of an evolutionary sequence in\nwhich young, bright objects with relatively steep spectra gradually\nevolve into old, faint objects with flat or inverted spectra.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-112339494", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-112339494", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/r6cj-a204", "primary_object": { "basename": "The_radio_spectrum_of_supernova_remnants.pdf", "url": "https://authors.library.caltech.edu/records/adpmr-svm06/files/The_radio_spectrum_of_supernova_remnants.pdf" }, "pub_year": "2014", "author_list": "Harris, D. E." }, { "id": "https://authors.library.caltech.edu/records/e6dkf-3sa21", "eprint_id": 47103, "eprint_status": "archive", "datestamp": "2023-08-19 03:40:44", "lastmod": "2024-01-13 16:06:31", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maltby-P", "name": { "family": "Maltby", "given": "P." } } ] }, "title": "Brightness Distribution in Discrete Radio Sources. II Observations with a North-South Interferometer", "ispublished": "unpub", "full_text_status": "public", "note": "The program of research in radio astronomy at the California Institute\nof Technology is supported by the United States Office of Naval Research under\nContract Nonr 220(19). The author wishes to thank G. J. Stanley, Acting\nDirector of the Observatory, and A. T. Moffet for helpful discussions, and\nseveral colleagues for their assistance in the observational program. The\nauthor is a recipient of a Fulbright Travel Grant and a grant from the Norwegian\nResearch Council for Science and the Humanities.\n\nAccepted Version - Brightness_distribution_in_discrete_radio_sources._II._Observations_with_a_north-south_interferometer.pdf
", "abstract": "Information about the brightness distribution in 165 radio sources\nhas been obtained at a wavelength of 31. 3 cm. The measurements were made\nwith the variable spacing interferometer at the Owens Valley Radio Observatory\nusing a north-south baseline. Primary sets of observations, giving\nthe visibility amplitude and the phase, were taken at transit at four different\nantenna spacings. Additional information about the brightness distribution\nwas obtained from observations at large hour angles, using the\nsame physical antenna separations. The results of the observations are\ngiven in tabular form and several visibility curves are show.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-102355101", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-102355101", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220(19)" }, { "agency": "Fulbright Travel Grant" }, { "agency": "Norwegian Research Council for Science and the Humanities" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/r5tq-cj19", "primary_object": { "basename": "Brightness_distribution_in_discrete_radio_sources._II._Observations_with_a_north-south_interferometer.pdf", "url": "https://authors.library.caltech.edu/records/e6dkf-3sa21/files/Brightness_distribution_in_discrete_radio_sources._II._Observations_with_a_north-south_interferometer.pdf" }, "pub_year": "2014", "author_list": "Maltby, P." }, { "id": "https://authors.library.caltech.edu/records/xq4ta-dw967", "eprint_id": 47109, "eprint_status": "archive", "datestamp": "2023-08-19 03:58:03", "lastmod": "2024-01-13 16:06:37", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maltby-P", "name": { "family": "Maltby", "given": "P." } }, { "id": "Moffett-A-T", "name": { "family": "Moffett", "given": "A. T." } } ] }, "title": "Brightness Distribution in Discrete Radio Sources III. The Structure of the Sources", "ispublished": "unpub", "full_text_status": "public", "note": "The authors wish to thank G. J. Stanley , Director of the Observatory,\nfor his interest in this work. One of us (P.M.) is the recipient\nof a Fulbright Travel Grant and a grant from the Norwegian Research\ncouncil for Science and the Humanities. The other (A.T.M.) has held a\nNational Science Foundation Fellowship during the course of this work.\nThe program of research in radio astronomy at the California Institute\nof Technology is supported by the United States Office of Naval Research\nunder Contract Nonr 220 (19).\n\nAccepted Version - Brightness_Distribution_in_Discrete_Radio_Sources__III._The_Structure_of_the_Sources.pdf
", "abstract": "The visibility functions of 195 radio sources are interpreted\nin terms of the structure of these sources. Of the 195 sources, 174\nare known or presumed to be extragalactic. Seventy-five of these\nextragalactic sources are resolved with the interferometer spacings\nused, and complex structure is found in all but 13. In the sources\nshowing complex structure, two similar components with nearly equal\nintensities are found in 15, 40 show two or more components of unequal\nintensities, while 7 appear to be a bright core surrounded by a halo.\nIt is suggested that the majority of all extragalactic sources have\ncomplex structure.\nData are also given on the brightness distributions in the 21\ngalactic sources observed. In contrast to the extragalactic sources,\nemission from the galactic sources is typically confined to a single\nregion.", "date": "2014-07-09", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20140709-113317664", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140709-113317664", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Office of Naval Research (ONR)", "grant_number": "Nonr 220 (19)" }, { "agency": "Norwegian Research Council for Science and the Humanities" }, { "agency": "NSF" }, { "agency": "Fulbright Travel Grant" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/36ky-5s81", "primary_object": { "basename": "Brightness_Distribution_in_Discrete_Radio_Sources__III._The_Structure_of_the_Sources.pdf", "url": "https://authors.library.caltech.edu/records/xq4ta-dw967/files/Brightness_Distribution_in_Discrete_Radio_Sources__III._The_Structure_of_the_Sources.pdf" }, "pub_year": "2014", "author_list": "Maltby, P. and Moffett, A. T." }, { "id": "https://authors.library.caltech.edu/records/qxz9g-dsj37", "eprint_id": 28840, "eprint_status": "archive", "datestamp": "2023-08-19 01:31:33", "lastmod": "2023-10-24 18:11:12", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Barnhill-R-C", "name": { "family": "Barnhill", "given": "R. C." } } ] }, "title": "Data on the Suitability of the White Mountains of California as an Observatory Site, [July 1949]", "ispublished": "unpub", "full_text_status": "public", "note": "Published - Robinson_Lab_Jul_1949_1_.pdf
", "abstract": "Monthly Report on Research Conducted Under Office of Naval Research Contract N6 ONR 24421", "date": "2012-01-18", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20120118-140449651", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120118-140449651", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "primary_object": { "basename": "Robinson_Lab_Jul_1949_1_.pdf", "url": "https://authors.library.caltech.edu/records/qxz9g-dsj37/files/Robinson_Lab_Jul_1949_1_.pdf" }, "pub_year": "2012", "author_list": "Barnhill, R. C." }, { "id": "https://authors.library.caltech.edu/records/gmc1s-axq39", "eprint_id": 28839, "eprint_status": "archive", "datestamp": "2023-08-19 01:26:14", "lastmod": "2023-10-24 18:11:10", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Earll-E", "name": { "family": "Earll", "given": "Elliott" } } ] }, "title": "Data on the Suitability of the White Mountains of California as an Observatory Site, [November 1948]", "ispublished": "unpub", "full_text_status": "public", "note": "Published - Robinson_Lab_Nov_1948_1_.pdf
", "abstract": "Monthly Report on Research Conducted Under Office of Naval Research Contract N6 ONR 24421", "date": "2012-01-18", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20120118-135659793", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120118-135659793", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "primary_object": { "basename": "Robinson_Lab_Nov_1948_1_.pdf", "url": "https://authors.library.caltech.edu/records/gmc1s-axq39/files/Robinson_Lab_Nov_1948_1_.pdf" }, "pub_year": "2012", "author_list": "Earll, Elliott" }, { "id": "https://authors.library.caltech.edu/records/ehrb5-cm855", "eprint_id": 35046, "eprint_status": "archive", "datestamp": "2023-08-19 10:46:18", "lastmod": "2023-10-19 23:41:56", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Leighton-R-B", "name": { "family": "Leighton", "given": "Robert B." } } ] }, "title": "A 10-Meter Telescope for Millimeter and Sub-Millimeter Astronomy", "ispublished": "unpub", "full_text_status": "public", "note": "Any complex technical enterprise, even a relatively modest one like this,\nrequires the substantial participation of many skilled persons and might not\nsucceed at all without the essential contributions of a special few. Extending\nas it did over several years from concept to completion, the present project\ninvolved so many persons directly or indirectly, that it would be most difficult\nto acknowledge all the individuals who contributed significantly to it. The\nfollowing partial list recognizes some of those who made special contributions.\nProfessional:\nEngineering and Design:\nBruce Rule:\nVictor Ehrgott:\nRobert Lyon:\nWalter Schaal:\nDish and mounting design concepts\nMount design layout\nFabrication concepts and initial tooling\nDetail design\nMechanical and Fabrication:\nDavid Vail:\nWalter Schaal:\nDish fabrication and technical supervision\nMount fabrication\nComputer Hardware and Software:\nMartin Ewing:\nH. Wayne Hammond:\nBarbara Zimmerman:\nTechnical:\nJoseph Lyvers:\nLarry Van Stone:\nJeffrey Clark:\nOVRO Staff:\nComputer system concepts\nComputer operating system software\nFORTH Language software\nPrototype dish fabrication\nPrototype dish fabrication\nDISH 1 fabrication and surface measurements\nTelescope Assembly, Wiring, and Adjustment:\nO. Wayne Hutton:\nChick O. Lackore:\nRonald E. Allen:\nMechanical and supervision\nMechanical and assembly\nElectrical layout and wiring\nStudent Technicians:\nJohn Bean:\nRaymond Waldo:\nMichael Norman:\nDonald Macglashen:\nEric Tollestrup:\nKurt Tollestrup:\nRobert Calvet:\nIsabella Lewis:\nNorman Murray:\n\n3-meter dish and early 10-meter prototype parts\nPrototype dish fabrication\nPrototype dish fabrication\nPrototype dish fabrication\nDISH 1 fabrication\nDISH 1 fabrication\nDISH 1 and DISH 2 fabrication\nDISH 2 fabrication\nDISH 2 fabrication\nFaculty and Research Investigators:\nCo-investigators\nAlan Moffet:\nGerry Neugebauer:\nResearch Investigators:\nThomas Phillips:\nPeter Wannier:\nElectrical system design\nInfrared instrumentation\n(Bell Laboratories) Receiver design and 1 millimeter\nmeasurements\nReceiver design and fabrication\n\nSubmitted - Leighton_Robert-AST_73-04908.pdf
", "abstract": "The design and construction of a prototype 10.4 meter, f/0.4 telescope\nintended for millimeter- and submillimeter-wave astronomy is described,\nwith particular emphasis on design features, fabrication techniques, and\nerror sources. The surface accuracy attained on a prototype dish was about\n50 \u00b5m rms; on the first of four \"production\" dishes, about 25 \u00b5m rms; the goal\nfor at least one of the four dishes is to be 10 \u00b5m rms or less. The reflecting\nsurface is sheet aluminum cemented to accurately machined honeycomb panels.\nThe 84 demountable panels are supported on a tubular steel- framework which is\nitself disassemblable into a few easily transportable pieces. A notable feature\nis that the dish may be disassembled and reassembled without significant loss\nof accuracy and without need for later readjustment, although the means for readjustment\nare provided. The mount is of the altazimuth fork type and has an\ninitial absolute pointing accuracy of 6 - 10\" and a tracking accuracy of\n1 - 2\" in the absence of strong wind gusts, which degrade the tracking accuracy\nsomewhat. The telescope, operated in an f/4.2 cassegrain mode at 230 GHz, has\na system effeciency greater than 50 percent. Three such telescopes are to be\ninstalled at Owens Valley Radio Observatory and used as a millimeter-wave\naperture synthesis radio interferometer. A fourth telescope, of especially\nhigh dish accuracy, is to be built and tested at OVRO and later moved to a\nhigh, dry mountain site for submillimeter infrared and radio astronomy.", "date": "1977-08", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20121023-144727561", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121023-144727561", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "AST 73-04908" } ] }, "local_group": { "items": [ { "id": "Owens-Valley-Radio-Observatory" } ] }, "doi": "10.7907/75rd-4h66", "primary_object": { "basename": "Leighton_Robert-AST_73-04908.pdf", "url": "https://authors.library.caltech.edu/records/ehrb5-cm855/files/Leighton_Robert-AST_73-04908.pdf" }, "pub_year": "1977", "author_list": "Leighton, Robert B." } ]