Antenna Surface Measurement Techniques
Richard Prestage (Green Bank Observatory)
The ability to quickly and precisely measure the figure (shape) and alignment of antenna reflector surfaces is critical for the characterization, commissioning and operation of radio telescopes. One traditional technique, which has been used for many years, is with-phase holography: the amplitude and phase of the far-field antenna pattern is measured, and the aperture plane amplitude and phase distributions are obtained via a Fourier transform. A complimentary technique which has been used with great success at a variety of telescopes in recent years is “phase-retrieval” holography: far field power patterns are measured at a number of different telescope focus positions, and the aperture plane amplitude and phase distributions are obtained by numerical inversion. Finally, terrestrial laser scanners show great promise for making large-scale measurements of reflector surfaces. In this talk, I will present the principles of each of these techniques, describe their use at the Green Bank Telescope, and review their relative merits and complimentary aspects.
Real-time, Commensal, Fast Transient Surveys with the Very Large Array
Casey Law (Berkeley)
Radio interferometers have the ability to precisely localize and better characterize the properties of sources. This ability is having a powerful impact on the study of fast radio transients such as Fast Radio Bursts, where a few milliseconds of data is enough to pinpoint a source at cosmological distances. However, recording interferometric data at millisecond cadence produces a terabyte-per-hour data stream that strains networks, computing systems, and archives. The realfast project is building the capability for thousands of hours of fast radio transient surveys through novel data distribution system and a dedicated GPU cluster integrated with the WIDAR correlator at the Jansky Very Large Array. This commensal system can detect transients in real time to trigger the recording of data for those rare, brief instants when the transient occurs. This makes it possible to search rapidly and commensally on a data stream that would otherwise be impossible to record. In this talk, I will describe the development of realfast at the VLA, its science scope, and expected outcomes.
Fast Radio Bursts
Matthew Bailes (Swinburne)
Fast Radio Bursts (FRBs) are a remarkable new class of radio transient discovered serendipitously during searches for single pulses from relatively nearby neutron stars. Their pulses last for typically 1–5 milliseconds and exhibit the cold plasma dispersion law seen in radio pulsars. It is yet to be firmly established as to what causes them. There are now over 50 FRBs known, and it has been firmly established that they come from cosmological distances with the localisation of the only FRB seen to repeat, FRB 121102. In this talk I will describe how FRBs were discovered and the latest results from Parkes and the UTMOST facility at Molonglo, along with future upgrades to make a “CHIME-SOUTH” facility.
Lessons from the Past and Present
Phil Kronberg (Toronto)
I recount a previous, remarkably well-conceived Canadian project to connect radio source counts with cosmology. Supernovae and related high-energy stellar events may lend themselves well to SKA investigations when combined with other investigations in optical, IR, X-ray, gamma-ray, and cosmic rays.
Seeing Red: Spectroscopy of Galactic Globular Clusters from 6500 A to 1 micron
Joel Roediger (NRC-HAA/Canadian Gemini Office)
The globular clusters that orbit the Milky Way are a treasure trove, providing evidence on a wide range of topics of astrophysical interest, from the scale of individual stars (stellar evolution) to the whole Galaxy itself (the mass of the Milky Way). The relative ease with which they can be observed, the massive volume of published data on them, and their very nature have also garnered the population of Galactic globular clusters (GGCs) an exalted status in the field of stellar population synthesis (SPS). This field seeks to interpret the integrated light from extragalactic stellar systems in terms of their underlying physical characteristics and relies on GGCs to enable baseline calibrations of the models that connect data to inference. Over the past decade, SPS analyses have begun to target galaxies at red/optical wavelengths and found tantalizing evidence that the stellar IMF varies systematically with galactic properties (like mass and metallicity). In this talk I will describe our survey with the Gemini Observatory to obtain integrated red/optical spectroscopy of GGCs that will enable the necessary tests of SPS models to secure claims of IMF variations in other galaxies.
Giant Exoplanet Archeology with Near-Infrared Imagers
Henry Ngo (DAO Plaskett Fellow)
To date, over 3700 planets have been found around other stars in our Galaxy. The discovery of these “exoplanets” raises many questions about the formation and migration histories of these planetary systems. For example, one type of giant planets, the “hot Jupiters” are gas giant planets similar to Jupiter but have orbital distances one-tenth the size of Mercury’s orbit around our Sun. In this talk, I will outline my previous and current work to uncover the histories of giant exoplanetary systems using near-infrared imagers to find companion stars and newly formed young planets.
UVic’s Software-Defined Radio (SDR) Earth Imager
Rodney Herring (UVic)
The Earth’s ionization layer is The Most Sensitive Earth Entity and its Largest Sensor. The disturbances to the ionization layer create waves on its lower surface that have been seen in ionosondes for ~100 years. What’s new? Nothing: these waves have always been there and concluded by Rishbeth to consist of 20% from space and 80% from underneath the ionization layer. A method to image these waves on the surface of the ionization layer will be presented and related to the transfer functions describing the power, energy and wavevector of the ionization layer’s disturbing event, the latter property enabling the location of the disturbing event if two or ideally three software-defined radio (SDR) Earth Imaging stations are established.
Another application of the SDR Earth Imager includes monitoring the atmosphere’s temperature, pressure and composition, information that will help with understanding weather and climate change.
University of Calgary MiNT Laboratory Research Activities
Leonid Belostotski (Calgary)
This talk will give a high-level overview of research activities undertaken at the University of Calgary Micro/Nano Technologies (MiNT) laboratory. Three broad research streams will be covered. First, the talk will discuss latest low-noise amplifier developments, which include a room-temperature 400-to-800 MHz LNA and a cryogenic CMOS LNA. The second research stream deals with the development of high-speed analog-to-digital converters. The results of previous work will be summarized and new projects will be discussed. Lastly, the talk will present some new beamforming-related research work. This includes multi-port LNAs and multi-port ADCs, delay-bandwidth induced errors in the active reflection coefficients, and the measurements of active reflection coefficients.
The Star Formation Law in Nearby Galaxies
Erik Rosolowsky (Alberta)
The process of star formation governs the secular evolution of galaxies. On the galactic scale, we have traditionally understood star formation in terms of an empirical “law” that describes the local star formation rate in terms of local conditions such as molecular gas content. In this talk, I will discuss new observations from the EDGE-CALIFA and PHANGS surveys that are helping to refine these simple empirical descriptions. We are finding that the local stellar environment and the degree of self-gravitation in the molecular gas both play central roles at controlling how efficiently galaxies form stars.
A Case Study of Triggered Star Formation in Cygnus X?
Soumen Deb (Alberta)
The Cygnus X region is one of the richest regions of star formation in the Milky Way Galaxy. It contains hundreds of distinct HII regions, numerous Wolf-Rayet and O-type stars, and several OB associations with Cygnus OB2 at the heart of the region. In a JCMT CO(3-2) pilot study of the area, we detected 47 molecular outflows, 27 of them previously unknown and widespread sequentially triggered star formation. In this talk, I will focus on a cometary feature at the outskirts of Cygnus OB2, which contains two proto-stars with newly discovered molecular outflows. We implement several techniques to analyze CO line emission as well as infrared and radio continuum data. This study helps us to understand the structure of the cometary feature, and more importantly the identification of the possible radiation source that might have triggered star formation in this molecular cloud.
A Bibliometric Analysis of Observatory Publications for the Period 2012-2016
Dennis Crabtree (DAO)
This paper is a biennial update on the productivity and impact of observatory publications. The primary scientific output of a telescope is the collection of papers published in refereed journals based on data from that telescope. A telescope’s productivity is measured by the number of papers published, while its scientific impact is the sum of each individual paper’s impact as measured quantitatively by the number of citations that the paper receives. The period covered by this paper are the years between 2012 and 2016.