Recent Submissions

  • The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

    Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, The Netherlands; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; SRON - Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, The Netherlands; Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205 La Laguna, Santa Cruz de Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain; Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Hertfordshire AL10 9AB, UK; Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice Cedex 4, France; INAF - Osservatorio Astronomico di Brera, Via Brera, 28, 20121 Milano, Italy; Aix Marseille Univ, CNRS, CNES, LAM, Laboratoire d'Astrophysique de Marseille, 13388 Marseille, France; INAF - Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy; et al. (Monthly Notices of the Royal Astronomical Society, 2024-05-01)
    WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, saw first light in late 2022. WEAVE comprises a new 2-deg field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366-959 nm at R ~ 5000, or two shorter ranges at $R\sim 20\, 000$. After summarizing the design and implementation of WEAVE and its data systems, we present the organization, science drivers, and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for ~3 million stars and detailed abundances for ~1.5 million brighter field and open-cluster stars; (ii) survey ~0.4 million Galactic-plane OBA stars, young stellar objects, and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey ~400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionized gas in z < 0.5 cluster galaxies; (vi) survey stellar populations and kinematics in ${\sim} 25\, 000$ field galaxies at 0.3 ≲ z ≲ 0.7; (vii) study the cosmic evolution of accretion and star formation using >1 million spectra of LOFAR-selected radio sources; and (viii) trace structures using intergalactic/circumgalactic gas at z > 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.
  • Observations of meteors in the Earth's atmosphere: Reducing data from dedicated double-station wide-angle cameras

    Department of Geodesy and Geoinformation Science, Technische Universität Berlin, Strasse des 17. Juni 135, Berlin, Germany; Armagh Observatory, College Hill, Armagh, BT61 9DG, UK; Department of Geodesy and Geoinformation Science, Technische Universität Berlin, Strasse des 17. Juni 135, Berlin, Germany; Germany Aerospace Center, Institute of Planetary Research, Rutherfordstr. 2, 12489, Berlin, Germany; Margonis, A.; Christou, A.; Oberst, J. (Astronomy and Astrophysics, 2018-10-01)
    Meteoroids entering the Earth's atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The software package is designed to fully utilise the high photometric quality of SPOSH images. This will facilitate the detection of meteor streams and studies of their trajectories. We have run simulations to assess the performance of the software by estimating the radiants, speeds, and magnitudes of synthetic meteors and comparing them with the a priori values. The estimated uncertainties in radiant location had a zero mean with a median deviation between 0.03<SUP>∘</SUP> and 0.11<SUP>∘</SUP> for the right ascension and 0.02<SUP>∘</SUP> and 0.07<SUP>∘</SUP> for the declination. The estimated uncertainties for the speeds had a median deviation between 0.40 and 0.45 km s<SUP>-1</SUP>. The brightness of synthetic meteors was estimated to within +0.01 m. We have applied the software package to 177 real meteors acquired by the SPOSH camera. The median propagated uncertainties in geocentric right ascension and declination were found to be of 0.64<SUP>∘</SUP> and 0.29<SUP>∘</SUP>, while the median propagated error in geocentric speed was 1.21 km s<SUP>-1</SUP>.
  • Scientific Goals of the Kunlun Infrared Sky Survey (KISS)

    School of Physics, University of New South Wales, Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, Northern Ireland, UK; Australian Astronomical Observatory, 105 Delhi Road, North Ryde, NSW 2113, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Mail Number H29, Hawthorn, VIC 3122, Australia; ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), Sydney, NSW 2006, Australia; Australian National University, Canberra, ACT 2611, Australia; Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China; School of Astronomy and Space Science, Nanjing University, Nanjing 210008, China; Nanjing Institute of Astronomical Optics &amp; Technology, Chinese Academy of Sciences, 188 Bancang Street, Nanjing 210042, China; School of Physics, University of New South Wales, Sydney, NSW 2052, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Mail Number H29, Hawthorn, VIC 3122, Australia; Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China; Texas A&amp;M University, College Station, Texas 77843, USA; et al. (Publications of the Astronomical Society of Australia, 2016-09-01)
    The high Antarctic plateau provides exceptional conditions for infrared observations on account of the cold, dry and stable atmosphere above the ice surface. This paper describes the scientific goals behind the first program to examine the time-varying universe in the infrared from Antarctica - the Kunlun Infrared Sky Survey (KISS). This will employ a 50cm telescope to monitor the southern skies in the 2.4μmK <SUB>dark</SUB> window from China's Kunlun station at Dome A, on the summit of the Antarctic plateau, through the uninterrupted 4-month period of winter darkness. An earlier paper discussed optimisation of the K <SUB>dark</SUB> filter for sensitivity (Li et al. 2016). This paper examines the scientific program for KISS. We calculate the sensitivity of the camera for the extrema of observing conditions that will be encountered. We present the parameters for sample surveys that could then be carried out for a range of cadences and sensitivities. We then discuss several science programs that could be conducted with these capabilities, involving star formation, brown dwarfs and hot Jupiters, exoplanets around M dwarfs, the terminal phases of stellar evolution, fast transients, embedded supernova searches, reverberation mapping of AGN, gamma ray bursts and the detection of the cosmic infrared background.
  • The cloudbow of planet Earth observed in polarisation

    European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748, Garching, Germany; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, UK; Meteorological Institute, Ludwig-Maximilians-University, Theresienstr. 37, 80333, Munich, Germany; Sterzik, Michael F.; Bagnulo, Stefano; Emde, Claudia; Manev, Mihail (Astronomy and Astrophysics, 2020-07-01)
    Context. Scattering processes in the atmospheres of planets cause characteristic features that can be particularly well observed in polarisation. For planet Earth, both molecular scattering (Rayleigh) and scattering by small particles (Mie) imprint specific signatures in its phase curve. Polarised phase curves allow us to infer physical and chemical properties of the atmosphere like the composition of the gaseous and liquid components, droplet sizes, and refraction indices. <BR /> Aims: An unequivocal prediction of a liquid-water-loaded atmosphere is the existence of a rainbow feature at a scattering angle of around 138-144°. Earthshine allows us to observe the primary rainbow in linear polarisation. <BR /> Methods: We observed polarisation spectra of Earthshine using FORS2 at the Very Large Telescope for phase angles from 33° to 65° (Sun-Earth-Moon angle). The spectra were used to derive the degree of polarisation in the B, V, R, and I passbands and the phase curve from 33° to 136°. The new observations extend to the smallest phases that can be observed from the ground. <BR /> Results: The degree of polarisation of planet Earth is increasing for decreasing phase angles downwards of 45° in the B, V, R, and I passbands. From comparison of the phase curve observed with models of an Earth-type atmosphere we are able to determine the refractive index of water and to constrain the mean water droplet sizes to 6-7μm. Furthermore, we can retrieve the mean cloud fraction of liquid water clouds to 0.3, and the mean optical depth of the water clouds to values between 10 and 20. <BR /> Conclusions: Our observations allow us to discern two fundamentally different scattering mechanisms of the atmosphere of planet Earth: molecular and particle scattering. The physical and chemical properties can be retrieved with high fidelity through suitable inversion of the phase curve. Observations of polarimetric phase curves of planets beyond the Solar System shall be extremely valuable for a thorough characterisation of their atmospheres.
  • Aliphatic hydrocarbon content of interstellar dust

    Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir, Turkey; ARC Centre of Excellence in Exciton Science, School of Chemistry, UNSW Sydney, NSW 2052, Australia; School of Physics, UNSW Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Mark Wainwright Analytical Centre, UNSW Sydney, NSW 2052, Australia; Günay, B.; Schmidt, T. W.; Burton, M. G.; Afşar, M.; Krechkivska, O.; Nauta, K.; et al. (Monthly Notices of the Royal Astronomical Society, 2018-10-01)
    There is considerable uncertainty as to the amount of carbon incorporated in interstellar dust. The aliphatic component of the carbonaceous dust is of particular interest because it produces a significant 3.4 μm absorption feature when viewed against a background radiation source. The optical depth of the 3.4 μm absorption feature is related to the number of aliphatic carbon C-H bonds along the line of sight. It is possible to estimate the column density of carbon locked up in the aliphatic hydrocarbon component of interstellar dust from quantitative analysis of the 3.4 μm interstellar absorption feature provided that the absorption coefficient of aliphatic hydrocarbons incorporated in the interstellar dust is known. We report laboratory analogues of interstellar dust by experimentally mimicking interstellar/circumstellar conditions. The resultant spectra of these dust analogues closely match those from astronomical observations. Measurements of the absorption coefficient of aliphatic hydrocarbons incorporated in the analogues were carried out by a procedure combining FTIR and <SUP>13</SUP>C NMR spectroscopies. The absorption coefficients obtained for both interstellar analogues were found to be in close agreement [4.76(8) × 10<SUP>-18</SUP> cm group<SUP>-1</SUP> and 4.69(14) × 10<SUP>-18</SUP> cm group<SUP>-1</SUP>], less than half those obtained in studies using small aliphatic molecules. The results thus obtained permit direct calibration of the astronomical observations, providing rigorous estimates of the amount of aliphatic carbon in the interstellar medium.
  • A method for mapping the aliphatic hydrocarbon content of interstellar dust towards the Galactic Centre

    Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir, Turkey; School of Physics, UNSW Sydney, NSW 2052, Australia; ARC Centre of Excellence in Exciton Science, School of Chemistry, UNSW Sydney, NSW 2052, Australia; School of Physics, UNSW Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK; Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir, Turkey; ARC Centre of Excellence in Exciton Science, School of Chemistry, UNSW Sydney, NSW 2052, Australia; Günay, B.; Burton, M. G.; Afşar, M.; Schmidt, T. W. (Monthly Notices of the Royal Astronomical Society, 2020-03-01)
    In the interstellar medium, the cosmic elemental carbon abundance includes the total carbon in both gas and solid phases. The aim of the study was to trial a new method for measuring the amount and distribution of aliphatic carbon within interstellar dust over wide fields of view of our Galaxy. This method is based on the measurement of the 3.4-μm absorption feature from aliphatic carbonaceous matter. This can readily be achieved for single sources using infrared (IR) spectrometers. However, making such measurements over wide fields requires an imaging IR camera, equipped with narrow-band filters that are able to sample the spectrum. While this cannot produce as good a determination of the spectra, the technique can be applied to potentially tens to hundreds of sources simultaneously, over the field of view of the camera. We examined this method for a field in the centre of the Galaxy, and produced a map showing the variation of 3.4-μm optical depth across it.
  • Method to observe Jupiter's radio emissions at high resolution using multiple LOFAR stations: a first case study of the Io-decametric emission using the Irish IE613, French FR606, and German DE604 stations

    School of Cosmic Physics, DIAS Dunsink Observatory, Dublin Institute for Advanced Studies, Dublin 15, Ireland; Station de Radioastronomie de Nançay, Observatoire de Paris, PSL Research University, CNRS, Université d'Orléans, F-18330 Nançay, France; School of Cosmic Physics, DIAS Dunsink Observatory, Dublin Institute for Advanced Studies, Dublin 15, Ireland; Station de Radioastronomie de Nançay, Observatoire de Paris, PSL Research University, CNRS, Université d'Orléans, F-18330 Nançay, France; LPC2E - Université d'Orléans/CNRS, 45071 Orléans, France; Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany; School of Cosmic Physics, DIAS Dunsink Observatory, Dublin Institute for Advanced Studies, Dublin 15, Ireland; School of Physics, Trinity College Dublin, Dublin, D02 PN40, Ireland; Astrophysics Research Group, School of Mathematics, Statistics and Applied Mathematics, National University of Ireland Galway, University Road, Galway, H91 H3CY, Ireland; Astrophysics Research Group, School of Mathematics, Statistics and Applied Mathematics, National University of Ireland Galway, University Road, Galway, H91 H3CY, Ireland; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DB, N. Ireland; School of Physics, Trinity College Dublin, Dublin, D02 PN40, Ireland; Department of Physics, University College Cork, Cork, T12 CY82, Ireland; Centre for Astronomy, School of Physics, National University of Ireland Galway, University Road, Galway, H91 TK33, Ireland; et al. (RAS Techniques and Instruments, 2022-04-01)
    The Low Frequency Array (LOFAR) is an international radio telescope array, consisting of 38 stations in the Netherlands and 14 international stations spread over Europe. Here, we present an observation method to study the Jovian decametric radio emissions from several LOFAR stations (here Birr Castle in Ireland, Nançay in France, and Postdam in Germany), at high temporal and spectral resolution. This method is based on prediction tools, such as radio emission simulations and probability maps, and data processing. We report an observation of Io-induced decametric emission from 2021 June, and a first case study of the substructures that compose the macroscopic emissions (called millisecond bursts). The study of these bursts makes it possible to determine the electron populations at the origin of these emissions. We then present several possible future avenues for study based on these observations. The methodology and study perspectives described in this paper can be applied to new observations of Jovian radio emissions induced by Io, but also by Ganymede or Europa, or Jovian auroral radio emissions.
  • Ultraviolet spectropolarimetry: conservative and nonconservative mass transfer in OB interacting binaries

    Department of Physics &amp; Astronomy, University of Southern California, 90089-0484, Los Angeles, CA, USA; Department of Physics &amp; Astronomy, University of Iowa, 52242, Iowa City, IA, USA; Department of Physics &amp; Astronomy, East Tennessee State University, 37614, Johnson City, TN, USA; Department of Physics and Astronomy, Western University, N6A 3K7, London, ON, Canada; GAPHE, University of Liège, Allée du 6 Aout 19c (B5C), 4000, Liège, Belgium; Département de physique, Université de Montréal, Campus MIL, 1375 Avenue Thérèse-Lavoie-Roux, H2V 0B3, Montréal, QC, Canada; Department of Physics &amp; Astronomy, University of Auckland, 38 Princes Street, 1010, Auckland, New Zealand; Armagh Observatory and Planetarium, College Hill, BT61 9DG, Armagh, Northern Ireland, UK; Department of Physics and Astronomy, Embry-Riddle Aeronautical University, 3700 Willow Creek Rd, 86301, Prescott, AZ, USA; Department of Physics and Astronomy, University of Denver, 2112 E. Wesley Ave., 80208, Denver, CO, USA; et al. (Astrophysics and Space Science, 2022-12-01)
    The current consensus is that at least half of the OB stars are formed in binary or multiple star systems. The evolution of OB stars is greatly influenced by whether the stars begin as close binaries, and the evolution of the binary systems depend on whether the mass transfer is conservative or nonconservative. FUV/NUV spectropolarimetry is poised to answer the latter question. This paper discusses how the Polstar spectropolarimetry mission can characterize the degree of nonconservative mass transfer that occurs at various stages of binary evolution, from the initial mass reversal to the late Algol phase, and quantify its amount. The proposed instrument combines spectroscopic and polarimetric capabilities, where the spectroscopy can resolve Doppler shifts in UV resonance lines with 10 km/s precision, and polarimetry can resolve linear polarization with 10<SUP>−3</SUP> precision or better. The spectroscopy will identify absorption by mass streams and other plasmas seen in projection against the stellar disk as a function of orbital phase, as well as scattering from extended splash structures, including jets. The polarimetry tracks the light coming from material not seen against the stellar disk, allowing the geometry of the scattering to be tracked, resolving ambiguities left by the spectroscopy and light-curve information. For example, nonconservative mass streams ejected in the polar direction will produce polarization of the opposite sign from conservative transfer accreting in the orbital plane. Time domain coverage over a range of phases of the binary orbit are well supported by the Polstar observing strategy. Special attention will be given to the epochs of enhanced systemic mass loss that have been identified from IUE observations (pre-mass reversal and tangential gas stream impact). We show how the history of systemic mass and angular momentum loss/gain episodes can be inferred via ensemble evolution through the r-q diagram. Combining the above elements will significantly improve our understanding of the mass transfer process and the amount of mass that can escape from the system, an important channel for changing the final mass and ultimate supernova of a large number of massive stars found in binaries at close enough separation to undergo interaction.
  • Nonsequential neural network for simultaneous, consistent classification, and photometric redshifts of OTELO galaxies

    Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, 04510, Ciudad de México, MX, USA; Instituto de Astrofísica de Canarias (IAC), 38200, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna (ULL), 38205, La Laguna, Tenerife, Spain; Institut de Radioastronomie Millimétrique (IRAM), Av. Divina Pastora 7, Local 20, 18012, Granada, España; Asociación Astrofísica para la Promoción de la Investigación, Instrumentación y su Desarrollo, ASPID, 38205, La Laguna, Tenerife, Spain; Instituto de Astrofísica de Canarias (IAC), 38200, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna (ULL), 38205, La Laguna, Tenerife, Spain; Asociación Astrofísica para la Promoción de la Investigación, Instrumentación y su Desarrollo, ASPID, 38205, La Laguna, Tenerife, Spain; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 DG, UK; Departamento de Física de la Tierra y Astrofísica, Instituto de Física de Partículas y del Cosmos (IPARCOS), Universidad Complutense de Madrid, 28040, Madrid, Spain; Depto. Astrofísica, Centro de Astrobiología (INTA-CSIC), ESAC Campus, Camino Bajo del Castillo s/n, 28692, Villanueva de la Cañada, Spain; Asociación Astrofísica para la Promoción de la Investigación, Instrumentación y su Desarrollo, ASPID, 38205, La Laguna, Tenerife, Spain; Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), 39005, Santander, Spain; Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, s/n, 18008, Granada, Spain; Ethiopian Space Science and Technology Institute (ESSTI), Entoto Observatory and Research Center (EORC), Astronomy and Astrophysics Research and Development Department, PO Box 33679, Addis Ababa, Ethiopia; Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, s/n, 18008, Granada, Spain; et al. (Astronomy and Astrophysics, 2021-11-01)
    Context. Computational techniques are essential for mining large databases produced in modern surveys with value-added products. <BR /> Aims: This paper presents a machine learning procedure to carry out a galaxy morphological classification and photometric redshift estimates simultaneously. Currently, only a spectral energy distribution (SED) fitting has been used to obtain these results all at once. <BR /> Methods: We used the ancillary data gathered in the OTELO catalog and designed a nonsequential neural network that accepts optical and near-infrared photometry as input. The network transfers the results of the morphological classification task to the redshift fitting process to ensure consistency between both procedures. <BR /> Results: The results successfully recover the morphological classification and the redshifts of the test sample, reducing catastrophic redshift outliers produced by an SED fitting and avoiding possible discrepancies between independent classification and redshift estimates. Our technique may be adapted to include galaxy images to improve the classification. <P />ARRAY(0x2881840)
  • Mapping the aliphatic hydrocarbon content of interstellar dust in the Galactic plane

    Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir, Turkey; School of Physics, UNSW Sydney, NSW 2052, Australia; School of Physics, UNSW Sydney, NSW 2052, Australia; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, Northern Ireland, UK; Department of Astronomy and Space Sciences, Ege University, 35100 Bornova, İzmir, Turkey; ARC Centre of Excellence in Exciton Science, School of Chemistry, UNSW Sydney, NSW 2052, Australia; Günay, B.; Burton, M. G.; Afşar, M.; Schmidt, T. W. (Monthly Notices of the Royal Astronomical Society, 2022-09-01)
    We implement a new observational method for mapping the aliphatic hydrocarbon content in the solid phase in our Galaxy, based on spectrophotometric imaging of the 3.4 $\mu$m absorption feature from interstellar dust. We previously demonstrated this method in a field including the Galactic Centre cluster. We applied the method to a new field in the Galactic Centre where the 3.4 $\mu$m absorption feature has not been previously measured and we extended the measurements to a field in the Galactic plane to sample the diffuse local interstellar medium, where the 3.4 $\mu$m absorption feature has been previously measured. We have analysed 3.4 $\mu$m optical depth and aliphatic hydrocarbon column density maps for these fields. Optical depths are found to be reasonably uniform in each field, without large source-to-source variations. There is, however, a weak trend towards increasing optical depth in a direction towards b = 0° in the Galactic Centre. The mean value of column densities and abundances for aliphatic hydrocarbon were found to be about several $\rm \times 10^{18} \, cm^{-2}$ and several tens × 10<SUP>-6</SUP>, respectively for the new sightlines in the Galactic plane. We conclude that at least 10-20 per cent of the carbon in the Galactic plane lies in aliphatic form.
  • Ultraviolet spectropolarimetry with Polstar: using Polstar to test magnetospheric mass-loss quenching

    Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, 19716, Newark, DE, USA; High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, 80307-3000, Boulder, CO, USA; Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St, 94304, Palo Alto, CA, USA; Department of Physics and Astronomy, Howard University, 20059, Washington, DC, USA; Center for Research and Exploration in Space Science and Technology, and X-ray Astrophysics Laboratory, NASA/GSFC, 20771, Greenbelt, MD, USA; Center for Research and Exploration in Space Science and Technology, and X-ray Astrophysics Laboratory, NASA/GSFC, 20771, Greenbelt, MD, USA; Instituto de Astrofísica de Canarias, E-38205, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, E-38206, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, E-38206, La Laguna, Tenerife, Spain; Department of Physics &amp; Astronomy, East Tennessee State University, 37614, Johnson City, TN, USA; Tartu Observatory, University of Tartu, Observatooriumi 1, 61602, Tõravere, Estonia; Department of Physics &amp; Astronomy, University of Iowa, 203 Van Allen Hall, 52242, Iowa City, IA, USA; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands; Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden; et al. (Astrophysics and Space Science, 2022-12-01)
    Polstar is a proposed NASA MIDEX space telescope that will provide high-resolution, simultaneous full-Stokes spectropolarimetry in the far ultraviolet, together with low-resolution linear polarimetry in the near ultraviolet. This observatory offers unprecedented capabilities to obtain unique information on the magnetic and plasma properties of the magnetospheres of hot stars. We describe an observing program making use of the known population of magnetic hot stars to test the fundamental hypothesis that magnetospheres should act to rapidly drain angular momentum, thereby spinning the star down, whilst simultaneously reducing the net mass-loss rate. Both effects are expected to lead to dramatic differences in the evolution of magnetic vs. non-magnetic stars.
  • UV spectropolarimetry with Polstar: protoplanetary disks

    Department of Physics and Astronomy, George Mason University, Fairfax, USA; Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Turku, Finland; Leibniz-Institut für Sonnenphysik, Freiburg, Germany; NASA GSFC, Greenbelt, USA; Department of Physics and Astronomy, University of Victoria, Victoria, Canada; School of Physics and Astronomy, University of Leeds, Leeds, UK; Clemson University, Clemson, USA; University of Iowa, Iowa City, USA; East Tennessee State University, Johnson City, USA; CNRS, ENS, UCBL, Observatoire de Lyon, Saint-Genis-Laval, France; et al. (Astrophysics and Space Science, 2022-12-01)
    Polstar is a proposed NASA MIDEX mission that carries a high resolution UV spectropolarimeter capable of measure all four Stokes parameters onboard a 60 cm telescope. The mission has been designed to pioneer the field of time-domain UV spectropolarimetry. Time domain UV spectropolarimetry offers the best resource to determine the geometry and physical conditions of protoplanetary disks from the stellar surface to &lt;5 AU. We detail two key objectives that a dedicated time domain UV spectropolarimetry survey, such as that enabled by Polstar or a similar mission concept, could achieve: 1) Test the hypothesis that magneto-accretion operating in young planet-forming disks around lower-mass stars transitions to boundary layer accretion in planet-forming disks around higher mass stars; and 2) Discriminate whether transient events in the innermost regions of planet-forming disks of intermediate mass stars are caused by inner disk mis-alignments or from stellar or disk emissions.
  • Understanding structure in line-driven stellar winds using ultraviolet spectropolarimetry in the time domain

    Department of Physics and Astronomy, University of Iowa, 52242, Iowa City, IA, USA; Armagh Observatory and Planetarium, College Hill, BT65 9DG, Armagh, Northern Ireland, UK; Penn State Scranton, 120 Ridge View Drive, 18512, Dunmore, PA, USA; Department of Physics and Astronomy, Howard University, 20059, Washington, DC, USA; Center for Research and Exploration in Space Science and Technology, and X-ray Astrophysics Laboratory, NASA/GSFC, 20771, Greenbelt, MD, USA; Center for Research and Exploration in Space Science and Technology, and X-ray Astrophysics Laboratory, NASA/GSFC, 20771, Greenbelt, MD, USA; Department of Physics &amp; Astronomy, East Tennessee State University, 37614, Johnson City, TN, USA; Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK; Département de physique, Université de Montréal, Complexe des Sciences, 1375 Avenue Thérèse-Lavoie-Roux, H2V 0B3, Montréal (QC), Canada; Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290, Versoix GE, Switzerland; GAPHE, Univ. of Liège, B5C, Allée du 6 Août 19c, B-4000, Liège, Belgium; Anton Pannekoek Institute for Astronomy and Astrophysics, University of Amsterdam, 1090 GE, Amsterdam, The Netherlands; et al. (Astrophysics and Space Science, 2022-12-01)
    The most massive stars are thought to lose a significant fraction of their mass in a steady wind during the main-sequence and blue supergiant phases. This in turn sets the stage for their further evolution and eventual supernova, and preconditions the surrounding medium for all following events, with consequences for ISM energization, chemical enrichment, and dust formation. Understanding these processes requires accurate observational constraints on the mass-loss rates of the most luminous stars, which can also be used to test theories of stellar wind driving. In the past, mass-loss rates have been characterized via collisional emission processes such as optical Hα and free-free radio emission, but these so-called density squared diagnostics require correction in the presence of widespread clumping. Recent observational and theoretical evidence points to the likelihood of a ubiquitously high level of such clumping in hot-star winds, but quantifying its effects requires a deeper understanding of the complex dynamics of radiatively driven winds and their stochastic instabilities. Furthermore, large-scale structures initiating in surface anisotropies and propagating throughout the wind can also affect wind driving and alter mass-loss diagnostics. Time series spectroscopy of high resonance-line opacity in the UV, capable of high resolution and high signal-to-noise, are required to better understand these complex dynamics, and more accurately determine mass-loss rates. The proposed Polstar mission (Scowen et al. 2022, this volume) provides the necessary resolution at the Sobolev (∼10 km s<SUP>−1</SUP>) or sound-speed (∼20 km s<SUP>−1</SUP>) scale, for over three dozen bright galactic massive stars with signal-to noise an order of magnitude above that of the celebrated MEGA campaign (Massa et al. 1995) of the International Ultraviolet Explorer (IUE), via continuous observations that track propagating structures through the winds in real time. Supporting geometric constraints are provided by the polarimetric capabilities present in all the datasets of such a mission.
  • The wide-field, multiplexed, spectroscopic facility WEAVE: Survey design, overview, and simulated implementation

    Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, the Netherlands; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; SRON - Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, the Netherlands; Kapteyn Astronomical Institute, Rijksuniversiteit Groningen, Landleven 12, 9747 AD Groningen, the Netherlands; Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK; RALSpace, STFC, Harwell, Didcot OX11 0QX, UK; Instituto de Astrofísica de Canarias, Calle Vía Láctea, s/n, 38205. La Laguna, Santa Cruz de Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain; Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Hertfordshire AL10 9AB, UK; Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Bd de l'Observatoire, CS 34229, 06304 Nice Cedex 4, France; INAF - Osservatorio Astronomico di Brera, Via Brera, 28, 20121 Milano, Italy; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France; INAF - Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy; et al. (Monthly Notices of the Royal Astronomical Society, 2023-03-01)
    WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366-959 nm at R ~ 5000, or two shorter ranges at R ~ 20 000. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for ~3 million stars and detailed abundances for ~1.5 million brighter field and open-cluster stars; (ii) survey ~0.4 million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey ~400 neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in z &lt; 0.5 cluster galaxies; (vi) survey stellar populations and kinematics in ~25 000 field galaxies at 0.3 ≲ z ≲ 0.7; (vii) study the cosmic evolution of accretion and star formation using &gt;1 million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at z &gt; 2. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.
  • Resolving the Core of R136 in the Optical

    Gemini Observatory/NSFs NOIRLab, Casilla 603, La Serena, Chile; Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile; Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515, USA; Gemini Observatory/NSFs NOIRLab, Casilla 603, La Serena, Chile; Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, UK; Gemini Observatory/NSFs NOIRLab, Casilla 603, La Serena, Chile; European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany; Department of Physics and Astronomy, University of Sheffield, Hounsfield Road, Sheffield, S3 7RH, UK; Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile; Kalari, Venu M.; Horch, Elliott P.; Salinas, Ricardo; et al. (The Astrophysical Journal, 2022-08-01)
    The sharpest optical images of the R136 cluster in the Large Magellanic Cloud are presented, allowing us for the first time to resolve members of the central core, including R136a1, the most-massive star known. These data were taken using the Gemini speckle imager Zorro in medium-band filters with effective wavelengths similar to BVRI achieving angular resolutions between 30-40 mas. All stars previously known in the literature, having V &lt; 16 mag within the central 2″ × 2″, were recovered. Visual companions (≥40 mas; 2000 au) were detected for the WN5h stars R136 a1 and a3. Photometry of the visual companion of a1 suggests it is of mid-O spectral type. Based on new photometric luminosities using the resolved Zorro imaging, the masses of the individual WN5h stars are estimated to be between 150 and 200 M <SUB>⊙</SUB>, lowering significantly the present-day masses of some of the most-massive stars known. These mass estimates are critical anchor points for establishing the stellar upper-mass function.
  • The PLATO field selection process. I. Identification and content of the long-pointing fields

    INAF - Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122, Padova, Italy ; Dipartimento di Fisica e Astronomia "Galileo Galilei", Università degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy; Dipartimento di Fisica e Astronomia "Galileo Galilei", Università degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy; INAF - Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122, Padova, Italy; Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Optische Sensorsysteme, Rutherfordstraße 2, 12489, Berlin-Adlershof, Germany; INAF - Osservatorio Astronomico di Roma, Via Frascati, 33, 00078, Monte Porzio Catone (RM), Italy; SSDC-ASI, Via del Politecnico, snc, 00133, Roma, Italy; Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489, Berlin-Adlershof, Germany; Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium; Department of Astrophysics, IMAPP, Radboud University Nijmegen, 6500, GL, Nijmegen, The Netherlands; Max Planck Institute for Astronomy, Koenigstuhl 17, 69117, Heidelberg, Germany; INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy; INAF - Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, 35122, Padova, Italy; Aix-Marseille Université, CNRS, CNES, Laboratoire d'Astrophysique de Marseille, Technopôle de Marseille-Etoile, 38, rue Frédéric Joliot-Curie, 13388, Marseille cedex 13, France; Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077, Göttingen, Germany; Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany; Center for Space Science, NYUAD Institute, New York University Abu Dhabi, Abu Dhabi, UAE; et al. (Astronomy and Astrophysics, 2022-02-01)
    PLAnetary Transits and Oscillations of stars is an ESA M-class satellite planned for launch by the end of 2026 and dedicated to the wide-field search of transiting planets around bright and nearby stars, with a strong focus on discovering habitable rocky planets hosted by solar-like stars. The choice of the fields to be pointed at is a crucial task since it has a direct impact on the scientific return of the mission. In this paper, we describe and discuss the formal requirements and the key scientific prioritization criteria that have to be taken into account in the Long-duration Observation Phase (LOP) field selection, and apply a quantitative metric to guide us in this complex optimization process. We identify two provisional LOP fields, one for each hemisphere (LOPS1 and LOPN1), and we discuss their properties and stellar content. While additional fine-tuning shall be applied to LOP selection before the definitive choice, which is set to be made two years before launch, we expect that their position will not move by more than a few degrees with respect to what is proposed in this paper.
  • 280 one-opposition near-Earth asteroids recovered by the EURONEAR with the Isaac Newton Telescope

    Isaac Newton Group of Telescopes (ING), Apto. 321, 38700 Santa Cruz de la Palma, Canary Islands, Spain ; Instituto de Astrofísica de Canarias (IAC), C/vía Láctea s/n, 38205 La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain; Amateur Astronomer, ROASTERR-1 Observatory, 400645, Cluj Napoca, Romania; Isaac Newton Group of Telescopes (ING), Apto. 321, 38700 Santa Cruz de la Palma, Canary Islands, Spain; Unidad de Astronomía, Facultad Ciencias Básicas, Universidad de Antofagasta, Chile; Astronomical Institute of the Romanian Academy, 5 Cutitul de Argint, 040557, Bucharest, Romania; Isaac Newton Group of Telescopes (ING), Apto. 321, 38700 Santa Cruz de la Palma, Canary Islands, Spain; Dpto. de Física Aplicada I, Escuela de Ingeniería de Bilbao, Universidad del País Vasco, 48940, Bilbao, Spain; Isaac Newton Group of Telescopes (ING), Apto. 321, 38700 Santa Cruz de la Palma, Canary Islands, Spain; National Solar Observatory, 3665 Discovery Drive, Boulder, CO, 80303, USA; Romanian Society for Meteors and Astronomy (SARM), Str. Tineretului 1, 130029, Targoviste, Romania; Amateur astronomer, 438, Cluj Napoca, Romania; Bucharest Astroclub, B-dul Lascar Catargiu 21, sect 1, Bucharest, 010662, Romania; et al. (Astronomy and Astrophysics, 2018-01-01)
    Context. One-opposition near-Earth asteroids (NEAs) are growing in number, and they must be recovered to prevent loss and mismatch risk, and to improve their orbits, as they are likely to be too faint for detection in shallow surveys at future apparitions. <BR /> Aims: We aimed to recover more than half of the one-opposition NEAs recommended for observations by the Minor Planet Center (MPC) using the Isaac Newton Telescope (INT) in soft-override mode and some fractions of available D-nights. During about 130 h in total between 2013 and 2016, we targeted 368 NEAs, among which 56 potentially hazardous asteroids (PHAs), observing 437 INT Wide Field Camera (WFC) fields and recovering 280 NEAs (76% of all targets). <BR /> Methods: Engaging a core team of about ten students and amateurs, we used the THELI, Astrometrica, and the Find_Orb software to identify all moving objects using the blink and track-and-stack method for the faintest targets and plotting the positional uncertainty ellipse from NEODyS. <BR /> Results: Most targets and recovered objects had apparent magnitudes centered around V ~ 22.8 mag, with some becoming as faint as V ~ 24 mag. One hundred and three objects (representing 28% of all targets) were recovered by EURONEAR alone by Aug. 2017. Orbital arcs were prolonged typically from a few weeks to a few years; our oldest recoveries reach 16 years. The O-C residuals for our 1854 NEA astrometric positions show that most measurements cluster closely around the origin. In addition to the recovered NEAs, 22 000 positions of about 3500 known minor planets and another 10 000 observations of about 1500 unknown objects (mostly main-belt objects) were promptly reported to the MPC by our team. Four new NEAs were discovered serendipitously in the analyzed fields and were promptly secured with the INT and other telescopes, while two more NEAs were lost due to extremely fast motion and lack of rapid follow-up time. They increase the counting to nine NEAs discovered by the EURONEAR in 2014 and 2015. <BR /> Conclusions: Targeted projects to recover one-opposition NEAs are efficient in override access, especially using at least two-meter class and preferably larger field telescopes located in good sites, which appear even more efficient than the existing surveys. <P />Table 2 is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A105">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A105</A>
  • Rubin Observatory LSST Transients and Variable Stars Roadmap

    Department of Astrophysics and Planetary Science, Villanova University, 800 Lancaster Ave, Villanova, PA 19085, USA; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA; Joseph R. Biden, Jr. School of Public Policy and Administration, University of Delaware, Newark, DE 19716, USA; Data Science Institute, University of Delaware, Newark, DE 19716, USA; Vera C. Rubin Observatory Construction Project, Chile; Las Cumbres Observatory (LCOGT), 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA; Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195, USA; South African Astronomical Observatory, PO Box 9, Observatory Rd, Observatory 7935, South Africa; Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; Department of Physics, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA; NASA Exoplanet Science Institute-Caltech/IPAC, 1200 E. California Blvd, Pasadena, CA 91125, USA; INAF Osservatorio Astronomico di Trieste (INAF-OATS), Via G.B. Tiepolo 11, 34143 Trieste (TS), Italy; Lehigh University, Department of Physics Deming Lewis Lab 16 Memorial Drive East, Italy; Departamento de Matemática y Física Aplicadas, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, Alonso de Rivera 2850, Concepción, Chile; et al. (Publications of the Astronomical Society of the Pacific, 2023-10-01)
    The Vera C. Rubin Legacy Survey of Space and Time (LSST) holds the potential to revolutionize time domain astrophysics, reaching completely unexplored areas of the Universe and mapping variability time scales from minutes to a decade. To prepare to maximize the potential of the Rubin LSST data for the exploration of the transient and variable Universe, one of the four pillars of Rubin LSST science, the Transient and Variable Stars Science Collaboration, one of the eight Rubin LSST Science Collaborations, has identified research areas of interest and requirements, and paths to enable them. While our roadmap is ever-evolving, this document represents a snapshot of our plans and preparatory work in the final years and months leading up to the survey's first light.
  • The European Solar Telescope

    Instituto de Astrofísica de Canarias, 38205, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain; Leibniz-Institut für Sonnenphysik (KIS), Schöneckstr. 6, 79104, Freiburg, Germany; Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008, Granada, Spain; Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden; Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165, Ondřejov, Czech Republic; Instituto de Astrofísica de Canarias, 38205, La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain; Astronomical Institute of the Slovak Academy of Sciences, 05960, Tatranská Lomnica, Slovakia; Leibniz-Institut für Sonnenphysik (KIS), Schöneckstr. 6, 79104, Freiburg, Germany; Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast, BT7 1NN, Northern Ireland, UK; European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ, Noordwijk, The Netherlands; Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236, Penteli, Greece; Laboratoire de Physique des Plasmas (LPP), École Polytechnique, IP Paris, Sorbonne Université, CNRS, Observatoire de Paris, Université PSL, Université Paris Saclay, Paris, France; Rosseland Centre for Solar Physics, University of Oslo, PO Box 1029, Blindern, 0315, Oslo, Norway; LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 5 place Jules Janssen, 92195, Meudon, France; et al. (Astronomy and Astrophysics, 2022-10-01)
    The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l'Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems.
  • Transient-optimized real-bogus classification with Bayesian convolutional neural networks - sifting the GOTO candidate stream

    Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; School of Physics &amp; Astronomy, Monash University, Victoria 3800, Australia; OzGRav-Monash, School of Physics and Astronomy, Monash University, Victoria 3800, Australia; Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK; Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK; Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain; School of Physics &amp; Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK; Armagh Observatory &amp; Planetarium, College Hill, Armagh BT61 9DG, UK; National Astronomical Research Institute of Thailand, 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai 50180 Thailand; Department of Physics &amp; Astronomy, University of Turku, Vesilinnantie 5, FI-20014 Turku, Finland; Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK; Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX, UK; et al. (Monthly Notices of the Royal Astronomical Society, 2021-05-01)
    Large-scale sky surveys have played a transformative role in our understanding of astrophysical transients, only made possible by increasingly powerful machine learning-based filtering to accurately sift through the vast quantities of incoming data generated. In this paper, we present a new real-bogus classifier based on a Bayesian convolutional neural network that provides nuanced, uncertainty-aware classification of transient candidates in difference imaging, and demonstrate its application to the datastream from the GOTO wide-field optical survey. Not only are candidates assigned a well-calibrated probability of being real, but also an associated confidence that can be used to prioritize human vetting efforts and inform future model optimization via active learning. To fully realize the potential of this architecture, we present a fully automated training set generation method which requires no human labelling, incorporating a novel data-driven augmentation method to significantly improve the recovery of faint and nuclear transient sources. We achieve competitive classification accuracy (FPR and FNR both below 1 per cent) compared against classifiers trained with fully human-labelled data sets, while being significantly quicker and less labour-intensive to build. This data-driven approach is uniquely scalable to the upcoming challenges and data needs of next-generation transient surveys. We make our data generation and model training codes available to the community.

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