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The Colours of the Outer Solar System Origins Survey (Col-OSSOS) has gathered high quality, near-simultaneous (g-r) and (r-J) colours of 92 Kuiper Belt Objects (KBOs) with (u-g) and (r-z) gathered for some. We present the current state of the survey and data analysis. Recognizing that the optical colours of most icy bodies broadly follow the reddening curve, we present a new projection of the optical-NIR colours, which rectifies the main non-linear features in the optical-NIR along the ordinates. We find evidence for a bifurcation in the projected colours which presents itself as a diagonal empty region in the optical-NIR. A reanalysis of past colour surveys reveals the same bifurcation. We interpret this as evidence for two separate surface classes: the BrightIR class spans the full range of optical colours and broadly follows the reddening curve, while the FaintIR objects are limited in optical colour, and are less bright in the NIR than the BrightIR objects. We present a two class model. Objects in each class consist of a mix of separate blue and red materials, and span a broad range in colour. Spectra are modelled as linear optical and NIR spectra with different slopes, that intersect at some transition wavelength. The underlying spectral properties of the two classes fully reproduce the observed structures in the UV-optical-NIR colour space ($0.4\lesssim\lambda\lesssim1.4 \mbox{ $\mu$m}$), including the bifurcation observed in the Col-OSSOS and H/WTSOSS datasets, the tendency for cold classical KBOs to have lower (r-z) colours than excited objects, and the well known bimodal optical colour distribution., Comment: 13 figures, 5 tables, submitted

We have attempted to transform the SATCON1 recommendations into a specific set of high-level software requirements with provisional names for convenience of reference. We note that each of these is a fairly major software effort if they are to be robust enough to support the community. However, in some cases relevant software already exists, and this document identifies those packages. In brief, the SATCON1 recommendations call for the ability to flag, mask and repair satellite trails affecting astronomical data (a software tool we call TrailMask), to predict when satellite trails may or will affect specific observations (which we call PassPredict), and to simulate the effects of satellite trails so that the community can assess the scientific impact of those effects on astronomical research.

We present the discovery of 2013 VZ₇₀, the first known horseshoe coorbital companion of Saturn. Observed by the Outer Solar System Origins Survey for 4.5 yr, the orbit of 2013 VZ₇₀ is determined to high precision, revealing that it currently is in “horseshoe” libration with the planet. This coorbital motion will last at least thousands of years but ends ∼10 kyr from now; 2013 VZ₇₀ is thus another example of the already-known “transient coorbital” populations of the giant planets, with this being the first known prograde example for Saturn (temporary retrograde coorbitals are known for Jupiter and Saturn). We present a theoretical steady-state model of the scattering population of trans-Neptunian origin in the giant planet region (2–34 au), including the temporary coorbital populations of the four giant planets. We expose this model to observational biases using survey simulations in order to compare the model to the real detections made by a set of well-characterized outer solar system surveys. While the observed number of coorbitals relative to the scattering population is higher than predicted, we show that the number of observed transient coorbitals of each giant planet relative to each other is consistent with a trans-Neptunian source.

In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two Centaur objects: 2014 YY49 on 2019 January 28 and 2013 NL24 on 2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius r=16⁺²₋₁ km and a geometric albedo Pᵥ = 0.13⁺⁰.⁰¹⁵₋₀.₀₂₅ for 2014 YY49 and a radius r = 66⁺⁵₋₅ km and a geometric albedo Pᵥ = 0.045⁺⁰.⁰⁰⁶₋₀.₀₀₈ for 2013 NL₂₄. To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two Centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two Centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects' colors and light curve amplitudes and on follow-on occultation efforts informed by this astrometry.

This document provides recommendations to the Government of Canada and the Canadian Space Agency in response to their call for feedback on the future of Canadian space exploration. The report focuses on how the construction and long-term placement of mega-constellations of satellites into Earth orbit will affect astronomy and the view of the night sky by all peoples, with attention to all Canadians. The broader discussion highlights several environmental concerns associated with the construction and maintenance of these mega-constellations. The eight recommendations here address ways that Canada can play a role in mitigating some of these negative effects through national and international initiatives. In drafting the recommendations, we take the approach that space needs to be developed sustainably. In this regard, we use the Brundtland Report's definition: "Sustainable development is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs." Thus, all recommendations here are made with the intent of minimizing the negative consequences of mega-constellations, while also recognizing that their development will continue., Comment: Corresponding authors: Boley and Lawler. Submitted to CSA on March 31, 2021

The cold classical Kuiper Belt Objects (KBOs) possess a high, $\gtrsim30\%$ binary fraction. Widely separated and dynamically fragile, these binary systems have been useful in tracing the origins of KBOs. A new class of binaries was recently identified by their colours. The so-called blue binaries are unanimously members of the less red compositional class, and exhibit a 100% binary fraction. They appear to be push-out survivors, emplaced in the classical region during Neptune's phases of outward migration. The presence of these binary systems implies that the majority of objects that formed near the cold classical region formed as binaries. Here we present new optical colour measurements of cold classical KBOs from the Colours of the Outer Solar System Origins Survey, including colours of a blue binary discovered by the Solar System Origins Legacy Survey -- 2015 RJ277. The increased size of the colours sample has resulted in order-of-magnitude decrease in the probability that the binaries and singles sample share the same colour distribution. From the Anderson-Darling statistic, this probability is only a 0.3%, while it is only 0.002% when utilizing the difference of means statistic. We find a hint that the blue binaries have inflated free inclinations compared to their red counterparts, consistent with the push-out origin for these bodies., Comment: Accepted for publication in the PSJ. 4 Figures

Here, we present results on the intrinsic collision probabilities, $ P_I$, and range of collision speeds, $V_I$, as a function of the heliocentric distance, $r$, in the trans-Neptunian region. The collision speed is one of the parameters, that serves as a proxy to a collisional outcome e.g., complete disruption and scattering of fragments, or formation of crater, where both processes are directly related to the impact energy. We utilize an improved and de-biased model of the trans-Neptunian object (TNO) region from the "Outer Solar System Origins Survey" (OSSOS). It provides a well-defined orbital distribution model of TNOs, based on multiple opposition observations of more than 1000 bodies. In this work we compute collisional probabilities for the OSSOS models of the main classical, resonant, detached+outer and scattering TNO populations. The intrinsic collision probabilities and collision speeds are computed using the ��pik's approach, as revised and modified by Wetherill for non-circular and inclined orbits. The calculations are carried out for each of the dynamical TNO groups, allowing for inter-population collisions as well as collisions within each TNO population, resulting in 28 combinations in total. Our results indicate that collisions in the trans-Neptunian region are possible over a wide range in ($r, V_I$) phase space. Although collisions are calculated to happen within $r\sim 20 - 200$~AU and $V_I \sim 0.1$~km/s to as high as $V_I\sim9$~km/s, most of the collisions are likely to happen at low relative velocities $V_I, 13 pages, 6 figures

A stellar occultation by the extreme large-perihelion trans-Neptunian object (541132) Lele��k��honua (also known by the provisional designation of 2015 TG387) was predicted by the Lucky Star project and observed with the Research and Education Collaborative Occultation Network on 2018 October 20 UT. A single detection and a nearby nondetection provide constraints for the size and albedo. When a circular profile is assumed, the radius is $r={110}_{-10}^{+14}$ km, corresponding to a geometric albedo ${p}_{V}={0.21}_{-0.05}^{+0.03}$, for an adopted absolute magnitude of H V = 5.6, typical of other objects in dynamically similar orbits. The occultation also provides a high-precision astrometric constraint., 7 figures

This white paper submitted for the 2020 Canadian Long-Range Planning process (LRP2020) presents the prospects for Canada and the Square Kilometre Array (SKA) from 2020-2030, focussing on the first phase of the project (SKA1) scheduled to begin construction early in the next decade. SKA1 will make transformational advances in our understanding of the Universe across a wide range of fields, and Canadians are poised to play leadership roles in several. Canadian key SKA technologies will ensure a good return on capital investment in addition to strong scientific returns, positioning Canadian astronomy for future opportunities well beyond 2030. We therefore advocate for Canada's continued scientific and technological engagement in the SKA from 2020-2030 through participation in the construction and operations phases of SKA1., Comment: 14 pages, 4 figures, 2020 Canadian Long-Range Plan (LRP2020) white paper

The Square Kilometre Array (SKA), an exciting new world observatory that will enable transformational science at metre and centimetre wavelengths for years to come, is rapidly becoming reality. The SKA will be built in two phases, with the first phase (SKA1) representing ~10% of the full facility (SKA2). The SKA1 Design Baseline development is almost complete, and construction is set to begin early in the next decade. When constructed, it will be the largest and most powerful general-purpose radio telescope operating from 50 MHz - 15 GHz for years to come. Scientific and technological participation in the SKA has been identified as a top priority for the Canadian astronomical community for almost twenty years. This white paper advocates for Canada’s continued scientific and technological participation in the SKA project, focussing on Canadian prospects for SKA1 from 2020-2030. SKA1 is poised to make fundamental advances across a broad range of fields by virtue of its combination of sensitivity, angular resolution, imaging quality and frequency coverage. SKA1 scientific goals align well with the strengths of Canadian researchers. Canada is a world leader in studies of pulsars, cosmic magnetism and transients, as well as in low-frequency cosmology. Our multi-wavelength expertise in galaxy evolution, multi-messenger astronomy and planetary system formation – in which radio observations play a critical role – is also a key strength. The Canadian community therefore has the potential to carry out important PI science with SKA1, as well as to play world-leading roles in a number of the transformational Key Science Projects (KSPs) that are anticipated to take up the majority of available telescope time. An examination of the KSP leadership opportunities afforded by a decade of full operations implies that a 6% participation in the SKA1 Design Baseline is well-matched to Canadian scientific capacity and ambitions. Canada is a leader in technological development for the SKA through effective partnerships between universities, the National Research Council (NRC) and industry. Our key SKA1 technological capabilities include the design and fabrication of correlators and beamformers, digitisers, low-noise amplifiers, signal processing, and monitor & control. These technologies provide a suite of possible in-kind contributions to offset construction costs for good return on the capital investment required to participate in SKA1 at a level commensurate with our scientific ambitions. Canada also has the computing platform and archive development expertise to make important contributions to the SKA Regional Centre (SRC) network that will deliver global SKA1 scientific computing capability. A Canadian SRC would leverage our national compute strength to provide processing, storage, and user support tailored to Canadian SKA1 needs while also fulfilling our SKA1 participation requirements. Canadian contributions to the SKA now span two decades, marked by scientific and technological leadership that persists today within a vibrant metre and centimetre-wave radio community. SKA1 is happening now. Canada at last has the opportunity to reap the scientific benefits of our contributions, while an early commitment to construction would maximize our impact on this phase and our technological benefits as well. The 2020 Canadian Long-Range Planning process (LRP2020) will determine the future of the SKA in Canada for the next decade and beyond. We make the following recommendations: Canada should participate in the construction and operations phases of SKA1. SKA1 Design Baseline construction, operations and a staged technology development program should be funded at a 6% level, commensurate with Canadian scientific ambitions. This commitment is estimated to cost $160M CAD over the period 2021-2030. Canada should participate in the SKA regional centre (SRC) network to ensure community access to the processing, storage and user support required to scientifically exploit SKA1. The cost of this participation at a level commensurate with Canadian scientific ambitions, and in accordance with SRC network guidelines, is estimated to be $45M CAD over the period 2021-2030 in addition to construction and operations funding. To meet its SKA1 compute needs, Canada should leverage its established strength in scientific computing platforms and archive development by hosting a Canadian SRC. The membership model through which Canada participates in the intergovernmental organisation (IGO) that will build and operate SKA1 should provide full scientific and technological access as well as leadership rights for Canadian researchers and industry. An agreement for Canadian participation in the IGO should be finalized as early as possible in the next decade in order to maximize our impact on the construction phase as well as to maximize opportunities for technological tender and procurement., White paper identifier W046

The application of machine learning (ML) methods to the analysis of astrophysical datasets is on the rise, particularly as the computing power and complex algorithms become more powerful and accessible. As the field of ML enjoys a continuous stream of breakthroughs, its applications demonstrate the great potential of ML, ranging from achieving tens of millions of times increase in analysis speed (e.g., modeling of gravitational lenses or analysing spectroscopic surveys) to solutions of previously unsolved problems (e.g., foreground subtraction or efficient telescope operations). The number of astronomical publications that include ML has been steadily increasing since 2010. With the advent of extremely large datasets from a new generation of surveys in the 2020s, ML methods will become an indispensable tool in astrophysics. Canada is an unambiguous world leader in the development of the field of machine learning, attracting large investments and skilled researchers to its prestigious AI Research Institutions. This provides a unique opportunity for Canada to also be a world leader in the application of machine learning in the field of astrophysics, and foster the training of a new generation of highly skilled researchers., White paper identifier W004

Recent developments have opened up an opportunity to join the Subaru telescope under favourable terms. With the demonstrated success of SCExAO and HSC, and first light of the PFS nearly upon us, the immediate prospects for Subaru to make breakthrough discoveries that align well with Canadian interests are excellent. In this white paper we describe the scientific and technical (instrumentation) opportunities that a partnership with Subaru would enable. IWe highlight the important synergies with TMT, MSE and Euclid, and how a relatively small investment in Subaru can significantly enhance our ability to take advantage of those facilities. In particular, access to PFS in the decade before MSE sees first light will be critical for ensuring Canadians have the technical and scientific expertise to fully exploit, and lead, science with that next generation spectroscopic facility. The partnership also has strategic value, as it represents an important step toward building an alliance of observatories on Maunakea, which itself has the potential for dramatically increasing scientific impact and reducing costs., White paper identifier W006

CASTOR (The Cosmological Advanced Survey Telescope for Optical and UV Research) is a proposed Canadian-led flagship mission designed to provide high-resolution imaging and spectroscopy in the UV/blue-optical spectral region (0.15-0.55 microns). In the current design, the imager will cover a 0.25 sq. deg. field of view simultaneously in three bands, providing a hundred-fold improvement in survey speed over the legendary, but aging, Hubble Space Telescope (HST). In addition, a multi-object Digital Micro-Mirror (DMD) spectrograph, covering an adjacent field of view, will provide moderate- to high-resolution UV spectroscopy, while a wide-field, low-resolution spectroscopic capability will be provided by a grism. CASTOR's UV imaging and spectroscopic capabilities will enable a vast range of science in the post-HST era, including the physics of star formation from our galaxy to the distant universe, exploring the atmospheres of exoplanets, improving constraints on dark energy, and studying the properties of the outer solar system. CASTOR's data will far surpass any previous UV/blue-optical surveys in terms of sensitivity and angular resolution and will provide complementary capabilities to longer-wavelength data from the Euclid and WFIRST missions, as well as the ground-based LSST. CASTOR will be a strategic asset for Canadian astronomy in the coming decade, showcase the capabilities of Canadian aerospace companies on a global stage, and provide unprecedented opportunities for education and public outreach. A series of CSA-sponsored scientific and technical studies carried out during the past decade have advanced the mission concept to a mature state, and international partners are now waiting for a commitment by Canada., White paper identifier W018

The Canadian astronomy community requires reliable and stable access to Digital Research Infrastructure (DRI) that is significantly resourced and presented via interfaces designed to serve the science user. The current funding model for both the hardware and software layers of Canada’s DRI is evolving and astronomers must take action to ensure that the new organization that forms to manage DRI funding (currently referred to as ‘newORG’ and ‘engageDRI’) is aware of and able to address the community’s needs. We propose a pathway that will lead towards the creation of the Canadian Astronomy Science Centre (CASC; working title) as a partnership between National Research Council (NRC) and the Canadian astronomy research community. CASC will become the entity responsible for management and advocacy of DRI in Canadian astronomy. Astronomy must have a coherent national voice through CASCA, incorporating the expertise of CADC, CANFAR, and university science groups, for Canada to maintain our position of leadership in research astronomy. Recommendation 1: Form a CASCA committee to develop strategies for the effective utilization of NRC, CANARIE, CFI, Compute Canada, and other DRI funding sources for the benefit of Canadian astronomy. This committee should develop recommendations and report these to the CASCA Executive who can then engage with all of the involved funding partners to ensure a coherent model for DRI in astronomy. Canadian astronomy needs to increase the funding going into DRI and we must develop new community-wide structures to manage this infrastructure. The CADC, backed by continuous NRC funding, is a central element of this infrastructure due to its expertise in building and maintaining stable, world-leading DRI that is has developed over the last 30 years. Currently, funding of the hardware and software platform for research is being maintained via project focused-CFI grants (such as CIRADA, CLASP, CHIME, etc.) within a funding model that excludes direct support for the CADC. Separately, NRC has continued to support CADC’s efforts to build the CANFAR science platform capacity so that this can act as unifying system for the various individual projects as well as to maintain CADC's capacity for data archiving and delivery. Maintaining the CADC’s world-leading expertise in the current system of funding via CFI grants whose funding distribution excludes CADC involvement is highly challenging. Particularly challenging, from a data volume and computing needs view, will be supporting SKA, CHIME and possibly LSST data within the increasingly complex data landscape. Ongoing and increased NRC funding to CADC is needed to deal with the challenges of creating an astronomy cyber platform that integrates Canada’s astronomy data sets. Recommendation 2: CASCA should communicate the increasing importance of a science platform for astronomy to NRC and encourage increased support to CADC to ensure that a robust platform is developed. In utilizing this increased support, CADC should develop a budget that is examined, critiqued, modified, and endorsed by a sub-committee of CASCA in communication with NRC. Where university-based groups are able to create and manage some components of the necessary science infrastructure, they should be encouraged to do so. The principal challenges for university groups are 1) to create infrastructure that serves a broad science community rather than a focused research project, 2) to integrate the infrastructure they create with existing national and international astronomy infrastructure and, most importantly, 3) to ensure the continued operation and ongoing development of their infrastructure reasonably far (more than a decade) into the future. Recommendation 3: CASCA should communicate with those other bodies that provide funding and resources for astronomy and demonstrate a unified vision of the importance of digital infrastructure to astronomy. The complementary strengths of NRC/CADC and university groups should be emphasized. Recommendation 4: The dialogue and processes established in Recommendations 1,2,3 should lead to the creation of a formal entity (Canadian Astronomy Science Centre) to provide a bridging partnership between the various funders and actors in Canadian astronomy DRI and establish the capacity and breadth of mission needed to create and maintain a robust Digital Research Infrastructure in Astronomy., White paper identifier W062

The Large Synoptic Survey Telescope (LSST) will revolutionize optical wide-field astronomy while opening the window to short time-domain astronomy. Many astronomy communities, like Canada's, largely do not have membership in the LSST. As a consequence, they have no proprietary data access but could benefit from LSST data products. We have conducted a survey of the Canadian community to gauge their interests with LSST, and what data products are most desirable to them. We find that the astronomy research of Canadians would greatly benefit from access to LSST data products. Canadian astronomers fall broadly into two categories: those interested in the time domain and LSST's alerts and those interested in more classical wide-field astronomy of the stationary sky. We have identified four data products in particular that the majority of responders desire. These data products represent a relatively low data volume compared to the full LSST pixel-to-catalog products. We present the idea of a Canadian LSST-light Science Platform that will host the four most desirable products upon their public release, serving access to all Canadians. This platform would act as a national facility that would largely satisfy the LSST-related data needs of the majority of Canadian astronomers at a fraction of the overall cost of full national membership. Hosting the public release imagery for worldwide access has been recognized as a highly valuable in-kind contribution to LSST operations, and could facilitate access to proprietary data for Canadian astronomers. Recommendation: we recommend that Canada establish an LSST Science Platform to enable Canadian astronomers to make full use of the LSST data set., White paper identifier W015

Micro- and nano-satellites offer cost-effective platforms for space technology development and for targeted investigations in astronomy.The original 1999 CubeSat design, based on 1 litre-sized cubes, is now the standard '1U' prototyping architecture.The Canadian Space Agency was an early adopter of micro-satellites.The MOST (Microvariability and Oscillation of Stars) telescope was Canada's first astronomy satellite.Launched in 2003, MOST offered a dedicated platform for asteroseismology that demonstrated the advantages of uninterrupted, long-duration staring observations well before the Kepler Mission adopted the same technique to discover thousands of extrasolar planets.MOST opened the astronomy time domain from space.The subsequent BRITE (BRIght Target Explorer) Constellation was the first space astronomy mission to be carried out with nano-satellites, with Canada designing all and contributing two of the six 8U-sized satellites.Its greatest advantage was its ability to stay pointed on a wide field (24 x 24 degres) monitoring up to 30 bright stellar targets for up to 6 months. Micro-satellite adoption remains slow in astronomy, mostly because of the need for large telescope apertures.However, as demonstrated by MOST and BRITE, time-domain photometry of bright objects, such as Milky Way stars and planetary systems, can be well-served by modest apertures.Improving detector technology is now opening micro-satellite platforms to fainter objects, multi-band photometry, non-optical wavelengths, and polarimetry. Canada is in a strong position to lead micro-satellite astronomy. Building small and cost-effective - but capable - space platforms will ensure that Canada stays at the forefront of space technology development. Focusing on a few key micro-satellite investigations will optimize the science impact of Canadian space astronomy.Early experience with Canadian micro-satellites also enhances Canadian expertise and HQP training for participation in larger international follow-on missions. The Canadian Space Agency currently operates two astronomy small-satellite missions, the Near Earth Object Surveillance Satellite (NEOSSat) and BRIght Target Explorer (BRITE) Constellation, and has two more missions under study: the Photometric Observations of Extrasolar Planets (POEP) and the Extrasolar Planet Polarimetry Explorer / Explorateur Polarimétrique des Planètes Extrasolaires (ÉPPÉ).NEOSSat's first Guest Observer call for proposals in September 2019 was heavily (4.8:1) over-subscribed, reflecting intense astronomy interest. BRITE Constellation has already demonstrated to be one of Canada's highest-publication impact observatories. Both POEP and ÉPPÉ promise novel, science-enabling capabilities in space-based time-domain astronomy with applications well beyond their primary exoplanet-focused goals. Reliable, dedicated funding to support research with the existing missions and to expand the astronomy small-satellite program will solidify Canada's trademark in space astronomy innovation., White paper identifier W054

There is a vibrant and effective planetary science community in Canada. We do research in the areas of meteoritics, asteroid and trans-Neptunian object orbits and compositions, and space weather, and are involved in space probe missions to study planetary surfaces and interiors. For Canadian planetary scientists to deliver the highest scientific impact possible, we have several recommendations. Our top recommendation is to join LSST and gain access to the full data releases by hosting a data centre, which could be done by adding to the CADC, which is already highly involved in hosting planetary data and supporting computational modelling for orbital studies. We also support MSE, which can provide spectroscopy and thus compositional information for thousands of small bodies. We support a Canadian-led microsatellite, POEP, which will provide small body sizes by measuring occultations. We support the idea of piggybacking space weather instruments on other astronomical space probes to provide data for the space weather community. Many Canadian planetary scientists are involved in space probe missions, but through haphazard and temporary arrangements like co-appointments at US institutions, so we would like the community to support Canadian researchers to participate in these large, international missions., White paper identifier W052

Euclid is an ESA-led medium class space mission selected in October 2011, with launch planned for 2022. The Euclid mission aims at understanding why the expansion of the Universe is accelerating and what is the nature of the source - commonly called dark energy - responsible for this acceleration. Dark energy represents around 75% of the energy content of the Universe today, and together with dark matter it dominates the Universe's matter-energy content. Understanding dark energy is one of the key goals of physics over the next decade. The imprints of dark energy and gravity will be tracked by Euclid using two complementary cosmological probes to capture signatures of the expansion rate of the Universe and the growth of cosmic structures: weak gravitational lensing; and galaxy clustering (both through baryonic acoustic oscillations and redshift-space distortions). Although low-redshift cosmology is the primary driver of the mission, a wide range of science will be possible with the Euclid data. The Euclid Mission aims to survey over 15,000 deg^2 of the extragalactic sky with imaging in a wide visible (riz) band at 0.1" resolution, near-infrared photometry (Y, J, and H) and near-infrared spectroscopy. As a result, the Euclid Mission will generate a vast data set for legacy science, including broadband visible images and near-infrared photometry of roughly 1.5 billion galaxies and near-infrared spectroscopy of roughly 25 million galaxies. Such a large data set will touch on many aspects of astrophysics, on many different scales, from the formation and evolution of galaxies down to the detection of brown dwarfs. In 2016, Canada joined the Euclid Consortium when CFHT approved the Canada-France Imaging Survey (CFIS) as a Large Program. CFIS, along with other ground-based surveys, will be used by Euclid to measure photometric redshifts in the northern sky. 27 faculty-level astronomers in Canada are members of the Euclid Consortium. In this white paper, we present a status update for Euclid, and a request that the committee make a strong recommendation that funds be allocated to support the exploitation of the Euclid data by Canadian researchers., White paper identifier W020

The Square Kilometre Array (SKA), an exciting new world observatory that will enable transformational science at metre and centimetre wavelengths for years to come, is rapidly becoming reality. The SKA will be built in two phases, with the first phase (SKA1) representing ~10% of the full facility (SKA2). The SKA1 Design Baseline development is almost complete, and construction is set to begin early in the next decade. When constructed, it will be the largest and most powerful general-purpose radio telescope operating from 50 MHz - 15 GHz for years to come. Scientific and technological participation in the SKA has been identified as a top priority for the Canadian astronomical community for almost twenty years. This white paper advocates for Canada’s continued scientific and technological participation in the SKA project, focussing on Canadian prospects for SKA1 from 2020-2030. SKA1 is poised to make fundamental advances across a broad range of fields by virtue of its combination of sensitivity, angular resolution, imaging quality and frequency coverage. SKA1 scientific goals align well with the strengths of Canadian researchers. Canada is a world leader in studies of pulsars, cosmic magnetism and transients, as well as in low-frequency cosmology. Our multi-wavelength expertise in galaxy evolution, multi-messenger astronomy and planetary system formation – in which radio observations play a critical role – is also a key strength. The Canadian community therefore has the potential to carry out important PI science with SKA1, as well as to play world-leading roles in a number of the transformational Key Science Projects (KSPs) that are anticipated to take up the majority of available telescope time. An examination of the KSP leadership opportunities afforded by a decade of full operations implies that a 6% participation in the SKA1 Design Baseline is well-matched to Canadian scientific capacity and ambitions. Canada is a leader in technological development for the SKA through effective partnerships between universities, the National Research Council (NRC) and industry. Our key SKA1 technological capabilities include the design and fabrication of correlators and beamformers, digitisers, low-noise amplifiers, signal processing, and monitor & control. These technologies provide a suite of possible in-kind contributions to offset construction costs for good return on the capital investment required to participate in SKA1 at a level commensurate with our scientific ambitions. Canada also has the computing platform and archive development expertise to make important contributions to the SKA Regional Centre (SRC) network that will deliver global SKA1 scientific computing capability. A Canadian SRC would leverage our national compute strength to provide processing, storage, and user support tailored to Canadian SKA1 needs while also fulfilling our SKA1 participation requirements. Canadian contributions to the SKA now span two decades, marked by scientific and technological leadership that persists today within a vibrant metre and centimetre-wave radio community. SKA1 is happening now. Canada at last has the opportunity to reap the scientific benefits of our contributions, while an early commitment to construction would maximize our impact on this phase and our technological benefits as well. The 2020 Canadian Long-Range Planning process (LRP2020) will determine the future of the SKA in Canada for the next decade and beyond. We make the following recommendations: Canada should participate in the construction and operations phases of SKA1. SKA1 Design Baseline construction, operations and a staged technology development program should be funded at a 6% level, commensurate with Canadian scientific ambitions. This commitment is estimated to cost $160M CAD over the period 2021-2030. Canada should participate in the SKA regional centre (SRC) network to ensure community access to the processing, storage and user support required to scientifically exploit SKA1. The cost of this participation at a level commensurate with Canadian scientific ambitions, and in accordance with SRC network guidelines, is estimated to be $45M CAD over the period 2021-2030 in addition to construction and operations funding. To meet its SKA1 compute needs, Canada should leverage its established strength in scientific computing platforms and archive development by hosting a Canadian SRC. The membership model through which Canada participates in the intergovernmental organisation (IGO) that will build and operate SKA1 should provide full scientific and technological access as well as leadership rights for Canadian researchers and industry. An agreement for Canadian participation in the IGO should be finalized as early as possible in the next decade in order to maximize our impact on the construction phase as well as to maximize opportunities for technological tender and procurement.

Internationally, wide field imaging and spectroscopy at optical/near-infrared wavelengths is having profound impacts in diverse areas of astronomy. The international portfolio of projects in this arena for the next decade has never been richer and the expectation for transformative discoveries has never been higher. We discuss numerous projects in which Canada has interests or involvement, many of which are the subject of dedicated white papers, and attempt to set the national and international context in which these projects should be viewed. Critically, we show that, without action being taken by the community and supported by the LRP, Canada is facing a lack of access to any of the emerging front-line ground-based optical wide field programs and facilities for almost the entirety of the 2020s. We provide a set of comments for consideration by the LRP and the community for how to ensure Canada instead is able to capitalize upon the riches of the next decade, to compete internationally, and to set itself in a leadership position fo the 2030s. These recommendations include obtaining new access to 2020 datasets and observatories, leveraging the enviable capacity and skills of CADC/CANFAR, and developing the community so it can excel in an increasingly crowded, and exciting, international scene., White paper identifier W025

The Large Synoptic Survey Telescope (LSST) is set to begin commissioning its instruments in 2021, with science verification commencing in 2022 and science operations in 2023. With its large field of view and 3.2 Gigapixel camera, it will scan 18,000 square degrees every few nights from 320-1050 nm. This cadence will not only build a deep co-added map of the sky to ~25th magnitude in its wide field and ~28th magnitude in its deep fields, but will enable transient science on the largest scale. It will produce millions of ‘alerts’ for bright new celestial objects each night. By the end of the nominal 11th data release, it will deliver 18 billion objects in 5.5 million images. LSST will revolutionize photometric survey science.There are a wide range of scientific collaborations under the LSST umbrella: the Stars, Milky Way and the Local Volume Collaboration, the Transients and Variable Stars Collaboration, the Dark Energy Science Collaboration, The Solar System Science Collaboration, The Active Galactic Nuclei Collaboration, the Strong Lensing Collaboration and the Informatics and Statistics Science Collaboration. We highlight the LSST science cases relevant to the Canadian community, and describe how LSST data will complement and transform science in these areas. In a separate white paper, we discuss the varied Canadian data access needs and LSST data products. We will describe how coordination with current and planned facilities and programs with Canadian participation and leadership, namely CFHT, CFIS/UNIONS, MSE, Gemini, and Euclid will leverage these science efforts even further. We discuss the proposed model for participation in LSST and motivate why a coordinated national strategy for Canadian data access is essential to ensuring both the continued Canadian scientific leadership in LSST, and how investing in the infrastructure and training necessary for LSST partnership would therefore be strategic for Canadian astronomy., White paper identifier W051

This state-of-the-profession white paper focuses on the interdisciplinary fields of astrostatistics and astroinformatics, in which modern statistical and computational methods are applied to and developed for astronomical data. Astrostatistics and astroinformatics have grown dramatically in the past ten years, with international organizations, societies, conferences, workshops, and summer schools becoming the norm. Canada’s formal role in astrostatistics and astroinformatics has been relatively limited, but there is a great opportunity --- and necessity --- for growth in this area. In the 2020s, extremely large astronomy datasets will be available from both Canadian- and internationally-funded projects and missions. Millions of dollars and thousands of human hours have been invested in order to obtain these data, and we need to make the most of these data when performing scientific inference. Novel statistical and computational methods from astrostatistics and astroinformatics will be the driving force in the next decade of scientific discovery, and interdisciplinary collaboration is key. In order to establish Canada as an international leader in astrostatistics and astroinformatics, we must first understand our current state in these areas. Thus, we conducted a survey of astronomers in Canada to gain information on the training mechanisms through which we learn statistical methods and to identify areas for improvement. We explore Canadian-based astronomers' exposure to and training in statistical methodology, their self-described statistical acumen, and their suggestions for improving training in statistics in astronomy programs and for increasing interdisciplinary collaboration with statisticians. In general, the results of our survey indicate that while astronomers see statistical methods as critically important for their research, they lack focused training in this area and wish they had received more formal training during all stages of education and professional development. These findings inform our recommendations for the Long Range Plan 2020 on how to increase interdisciplinary connections between astronomy and statistics at the institutional, national, and international levels over the next ten years. We recommend specific, actionable ways to increase these connections, and discuss how interdisciplinary work can benefit not only research but also astronomy's role in training Highly Qualified Personnel (HQP) in Canada., White paper identifier W010

In this white paper (WP), we highlight several examples of small and moderate aperture telescopes that are being used for education and/or research. We further discuss potential costs for establishing new, small observatories, as well as joining existing international consortia. The WP includes a brief overview of select observing sites, with a discussion on how small telescopes at exceptional observing locations can be competitive, under certain circumstances, with larger and more expensive facilities located at poorer sites. Furthermore, small and moderate telescope facilitates enable on-demand observing and/or unique observing opportunities that may not be possible at large (and often oversubscribed) telescopes. While not meant to be all-encompassing, we discuss research programs associated with CanCON, Dragonfly Telephoto Array, ESA's Flyeye, Evryscope, Next-Generation Transit Survey, The Plaskett and the DAO 1.2 metre, the University of British Columbia Southern Observatory, the WIYN and SMARTS 0.9 metres, and the Zwicky Transient Facility. Science programs advanced by these facilities address, for example, exoplanets, binaries, variability, Solar System minor bodies, low-surface brightness structures, spectroscopy, microlensing, and large sky surveys. We further discuss commercial telescope pay-for-service options through iTelescope. In addition to research, these facilities enable many different types of educational experiences for wide range of people, from high school students to undergraduates to graduate students to postdocs. Potential uses include direct observing by upper-level astronomy undergraduates and graduate students and incorporation of observing and citizen science into large service courses. Maintenance itself necessitates physically working with a research telescope and offers unique student training opportunities -- astronomy undergraduates at UBC participated in the USO's installation at Cerro Tololo Inter-American Observatory, for example. Canada should remain committed to partnering with large, international observatories such as CFHT, Gemini, and TMT, but it should also negotiate international agreements and commit funding to expand the use of small, capable research observatories at domestic and international sites through coordination with the NRC, the Tri-Council, and the Canadian Foundation for Innovation. Both capital and operational costs (with site rental costs allowed) need to be included in support possibilities. CASCA should establish and maintain a small to moderate telescope expression of interest database that would help to facilitate Canadian institutions in organizing consortia, particularly for smaller institutions. The astronomical community should work with the NRC to make existing facilities more accessible to the astronomical community for research. This could involve, for example, automating the Plaskett and/or providing travel funds for supporting classical observing modes. Finally, a small to moderate aperture facility in the Arctic would be a world-class observatory and should be advanced over the next decade., White paper identifier W013

(Abridged from Executive Summary) This white paper focuses on the interdisciplinary fields of astrostatistics and astroinformatics, in which modern statistical and computational methods are applied to and developed for astronomical data. Astrostatistics and astroinformatics have grown dramatically in the past ten years, with international organizations, societies, conferences, workshops, and summer schools becoming the norm. Canada's formal role in astrostatistics and astroinformatics has been relatively limited, but there is a great opportunity and necessity for growth in this area. We conducted a survey of astronomers in Canada to gain information on the training mechanisms through which we learn statistical methods and to identify areas for improvement. In general, the results of our survey indicate that while astronomers see statistical methods as critically important for their research, they lack focused training in this area and wish they had received more formal training during all stages of education and professional development. These findings inform our recommendations for the LRP2020 on how to increase interdisciplinary connections between astronomy and statistics at the institutional, national, and international levels over the next ten years. We recommend specific, actionable ways to increase these connections, and discuss how interdisciplinary work can benefit not only research but also astronomy's role in training Highly Qualified Personnel (HQP) in Canada., White paper E017 submitted to the Canadian Long Range Plan LRP2020

International audience; The small bodies in the outer Solar System, called trans-Neptunian objects (TNOs), have a variety of surface types and orbital classifications. The cold classicals, which formed in situ, and the dynamically excited objects, which were likely scattered into their current locations, have distinct surface types. These surface types can be robustly identified using photometry in the combination of g, r, and z bands. We investigate the 2:1 resonance, which is located just outside the cold classical belt, to see whether this resonance harbors trapped cold classical surfaces. These would have been captured during a period of smooth sweeping migration by Neptune. We have acquired photometry of 17 of our 34 targets in 2018, and our results exclude a slow smooth sweeping of the entire cold classical region by Neptune's 2:1 resonance.

International audience; We propose a new compositional model for Kuiper Belt Objects that can account for many of the observed properties of those bodies, including their colour, and spectral behaviour. This model successfully accounts for the links to other related bodies, including the satellite Phoebe. The model asserts that the majority of KBOs consist of reddened carbonaceous material. If true, this implies that neutral class KBOs share a primordial link with the carbonaceous asteroids, the same bodies that scattered in to become the C-types in the asteroid belt.

The application of machine learning (ML) methods to the analysis of astrophysical datasets is on the rise, particularly as the computing power and complex algorithms become more powerful and accessible. As the field of ML enjoys a continuous stream of breakthroughs, its applications demonstrate the great potential of ML, ranging from achieving tens of millions of times increase in analysis speed (e.g., modeling of gravitational lenses or analysing spectroscopic surveys) to solutions of previously unsolved problems (e.g., foreground subtraction or efficient telescope operations). The number of astronomical publications that include ML has been steadily increasing since 2010. With the advent of extremely large datasets from a new generation of surveys in the 2020s, ML methods will become an indispensable tool in astrophysics. Canada is an unambiguous world leader in the development of the field of machine learning, attracting large investments and skilled researchers to its prestigious AI Research Institutions. This provides a unique opportunity for Canada to also be a world leader in the application of machine learning in the field of astrophysics, and foster the training of a new generation of highly skilled researchers., Comment: White paper E015 submitted to the Canadian Long Range Plan LRP2020

While collisional families are common in the asteroid belt, only one is known in the Kuiper belt, linked to the dwarf planet Haumea. The characterization of Haumea's family helps to constrain its origin and, more generally, the collisional history of the Kuiper belt. However, the size distribution of the Haumea family is difficult to constrain from the known sample, which is affected by discovery biases. Here, we use the Outer Solar System Origins Survey (OSSOS) Ensemble to look for Haumea family members. In this OSSOS XVI study we report the detection of three candidates with small ejection velocities relative to the family formation centre. The largest discovery, 2013 UQ15, is conclusively a Haumea family member, with a low ejection velocity and neutral surface colours. Although the OSSOS Ensemble is sensitive to Haumea family members to a limiting absolute magnitude (Hr) of 9.5 (inferred diameter of ~90 km), the smallest candidate is significantly larger, Hr = 7.9. The Haumea family members larger than approximately 20 km in diameter must be characterized by a shallow H-distribution slope in order to produce only these three large detections. This shallow size distribution suggests that the family formed in a graze-and-merge scenario, not a catastrophic collision., Comment: 11 pages, 3 figures, 3 tables

This white paper submitted for the 2020 Canadian Long-Range Planning process (LRP2020) presents the prospects for Canada and the Square Kilometre Array (SKA) from 2020-2030, focussing on the first phase of the project (SKA1) scheduled to begin construction early in the next decade. SKA1 will make transformational advances in our understanding of the Universe across a wide range of fields, and Canadians are poised to play leadership roles in several. Canadian key SKA technologies will ensure a good return on capital investment in addition to strong scientific returns, positioning Canadian astronomy for future opportunities well beyond 2030. We therefore advocate for Canada's continued scientific and technological engagement in the SKA from 2020-2030 through participation in the construction and operations phases of SKA1., 14 pages, 4 figures, 2020 Canadian Long-Range Plan (LRP2020) white paper

All surveys include observational biases, which makes it impossible to directly compare properties of discovered trans-Neptunian Objects (TNOs) with dynamical models. However, by carefully keeping track of survey pointings on the sky, detection limits, tracking fractions, and rate cuts, the biases from a survey can be modelled in Survey Simulator software. A Survey Simulator takes an intrinsic orbital model (from, for example, the output of a dynamical Kuiper belt emplacement simulation) and applies the survey biases, so that the biased simulated objects can be directly compared with real discoveries. This methodology has been used with great success in the Outer Solar System Origins Survey (OSSOS) and its predecessor surveys. In this chapter, we give four examples of ways to use the OSSOS Survey Simulator to gain knowledge about the true structure of the Kuiper Belt. We demonstrate how to statistically compare different dynamical model outputs with real TNO discoveries, how to quantify detection biases within a TNO population, how to measure intrinsic population sizes, and how to use upper limits from non-detections. We hope this will provide a framework for dynamical modellers to statistically test the validity of their models., Comment: accepted as a chapter in the "Frontiers in Astronomy and Space Sciences" research topic "From Comets to Pluto and Beyond"

We report the discovery of a trans-Neptunian object (TNO) plausibly diffusing out of the inner Oort Cloud reservoir. This TNO is on an orbit with q ~ 50 AU, a ~ 700 AU, the largest semi-major axis yet detected for an orbit with perihelion q beyond the q ≤ 38 zone of strong influence of Neptune, exceeding the semi-major axes of (90377) Sedna, 2012 VP113 and 2010 GB174. Such objects are rarely observed. Trans-Neptunian objects with these high orbital perihelia have no confirmed formation mechanism in the present planetary architecture of the Solar System. The orbit of this new TNO can be formed by inward diffusion of objects from a Galactic-tide-dominated population with a ~ 1000-2000 AU; the formation mechanism is highly inefficient, and would require on the order of a hundred times more objects in that population than in the a ~ 700 AU population. We also report colour and light curve measurements of the new TNO with Gemini North and Subaru-HSC. The longitude of the ascending node and argument of perihelion of this TNO's orbit have implications for the hypothesis of a ninth planet.

International audience; The surfaces of trans-Neptunian objects (TNOs) are poorly understood. Other than the large objects which exhibit signatures of various ices, very little has been discerned about the compositions of most TNOs. In recent years, some concrete knowledge about the distribution of surface colours of small TNOs has come to light. It is now generally accepted that small TNOs fall into at least three classes of object based on their surface colours and albedo. TNO surface type is also correlated with dynamical class, with certain types of TNO being found primarily in certain regions of the outer Solar System. This correlation presents the intriguing idea that the surfaces of TNOs contain information on more than composition, but as well hold the key to understanding the dynamical processes that lead to the giant planets violently dispersing the protoplanetesimal disk and populating the Kuiper Belt region. It is around this idea that the Col-OSSOS survey is predicated. This 4 year program which started in 2014B is simultaneously using the Gemini-North and Canada-France-Hawaii telescopes to gather near simultaneous u, g, r, and J spectral photometry of all targets in the Outer Solar System Origins Survey (OSSOS) brighter than r’=23.5 (~140 expected). The focus of Col-OSSOS is completeness and consistency, with the same SNR=25 being reached in all bands, for all targets brighter than our depth limit.Col-OSSOS will provide a combined compositional-dynamical map from which key hypotheses about the Solar System's cosmogony can be tested. For example, by mapping the fraction of TNOs with cold-classical like surface colours, we will be able to determine how much of the belt was populated by dynamical scattering versus sweep-up from Neptune. Further, we will be able to constrain the compositional homogeneity of the protoplanetesimal disk. The surfaces of TNOs must reflect that homogeneity; a heterogeneous disk will result in a clumpy colour distribution with many unique types, while a homogeneous disk will result in a smooth distribution of colours with only a few distinct types. Here we will present preliminary results and report on the initial progress of the survey.

We present results from the earliest observations of DEBRIS, a Herschel Key Programme to conduct a volume- and flux-limited survey for debris discs in A-type through M-type stars. PACS images (from chop/nod or scan-mode observations) at 100 and 160 micron are presented toward two A-type stars and one F-type star: beta Leo, beta UMa and eta Corvi. All three stars are known disc hosts. Herschel spatially resolves the dust emission around all three stars (marginally, in the case of beta UMa), providing new information about discs as close as 11 pc with sizes comparable to that of the Solar System. We have combined these data with existing flux density measurements of the discs to refine the SEDs and derive estimates of the fractional luminosities, temperatures and radii of the discs., to be published in A&A, 5 pages, 2 color figures

38th Meeting of the AAS Division for Planetary Sciences, DPS meeting #38, #37.03, 8-13 October 2006, 8-13 October 2006

2007 AAS/AAPT Joint Meeting, American Astronomical Society Meeting 209, #25.09, 5-10 January, 2007, Seattle, Washington, USA

International audience

The universality of the globular cluster luminosity function (GCLF) contrasts the variation seen in the specific frequency ($S_N$). The variation in $S_N$ has been shown to follow a linear relation with $L_X$ for brightest cluster galaxies (Blakeslee, J. 1997, Harris, W.E. et al. 1998). Further, the variation of $S_N$ with galactic radius within individual giant ellipticals is seen to be a constant fraction of the gas density (McLaughlin 1998). There are now a number of galaxies for which direct mass estimates based on the radial velocities of the globular clusters are available. By comparing the mass of galaxies determined in this way with the number of clusters within these galaxies we show that the fraction of mass which is converted into globular clusters is constant independent of galaxy type or environment. This implies that the process of globular cluster formation is not influenced by the host galaxy and supports the notion of the universal GCLF.

Motivated by a desire to understand the size distributon of the Kuiper Belt, an observing program was conducted at the Mount Palomar 5-m telescope from 1994-1996. The observations consisted of follow-up observations of known objects (in order to improve their very indeterminate orbits), and deep exposures on a single field to search for small objects below the limiting magnitudes of other surveys. Eighteen object recoveries were successfully obtained over the course of the follow-up program. Data reduction of the deep fields consisted of a software recombination of many fields shifted at different angular rates in order to detect objects at differing heliocentric distances. We set an upper limit of, 4 pages, 2 figures, accepted by A&A Letters