I. A. Steele
A5069980422- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Particle Accelerators and Free-Electron Lasers
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Distributed and Parallel Computing Systems
- Geomagnetism and Paleomagnetism Studies
- Advanced Vision and Imaging
- Ubiquitin and proteasome pathways
- Spectroscopy and Laser Applications
- CCD and CMOS Imaging Sensors
- Neutrino Physics Research
Liverpool John Moores University
2015-2024
University of Oxford
2018-2020
Rutherford Appleton Laboratory
2014-2020
Max Planck Society
2018
University of Manchester
2018
The Open University
2016
Max Planck Institute for Extraterrestrial Physics
2016
Technical University of Munich
2016
Smithsonian Astrophysical Observatory
2012
University of Southampton
1995-2011
Gaia Data Release 2 (Gaia DR2) contains results for 1693 million sources in the magnitude range 3 to 21 based on observations collected by European Space Agency satellite during first 22 months of its operational phase. We describe input data, models, and processing used astrometric content DR2, validation these performed within astrometry task. Some 320 billion centroid positions from pre-processed CCD were estimate five parameters (positions, parallaxes, proper motions) 1332 sources,...
Gaia Early Data Release 3 (Gaia EDR3) contains results for 1.812 billion sources in the magnitude range G = to 21 based on observations collected by European Space Agency satellite during first 34 months of its operational phase. We describe input data, models, and processing used astrometric content EDR3, as well validation these performed within astrometry task. The broadly followed same procedures DR2, but with significant improvements modelling observations. For time data processing,...
Merging neutron stars offer an exquisite laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of electromagnetic counterpart EM170817 to gravitational waves (GW170817) detected from merging stars. By synthesizing a panchromatic dataset, we demonstrate that are long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma-rays seen dissimilar classical short gamma-ray bursts with...
Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing all except Mercury. We report detection a with microlensing. identify two masses ∼0.71 and ∼0.27 times mass Jupiter orbital separations ∼2.3 ∼4.6 astronomical units orbiting primary star ∼0.50 at distance ∼1.5 kiloparsecs. This...
Abstract We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). used Hubble Space Telescope (HST) to carry out precise astrometry source star long-duration ( t E ≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in direction Galactic bulge. HST imaging, conducted at eight epochs over interval 6 yr, reveals a clear relativistic astrometric deflection...
The Liverpool Telescope is a 2.0 metre robotic telescope that operating unattended at the Observatorio del Roque de Los Muchachos, Spain. This paper gives an overview of design and implementation its instrumentation presents snapshot current performance during commissioning process. Science observations are under way, we give brief highlights from number programmes have been enabled by nature telescope.
We detect a Neptune mass ratio (q ≃ 8 × 10-5) planetary companion to the lens star in extremely high magnification (A ~ 800) microlensing event OGLE-2005-BLG-169. If parent is main-sequence star, it has M 0.5 M☉, implying planet of ~13 M⊕ and projected separation ~2.7 AU. When intensely monitored over their peak, high-magnification events similar OGLE-2005-BLG-169 have nearly complete sensitivity planets with separations 0.6-1.6 Einstein radii, corresponding 1.6-4.3 AU present case. Only two...
We present the preliminary design of WEAVE next generation spectroscopy facility for William Herschel Telescope (WHT), principally targeting optical ground-based follow up upcoming (LOFAR) and spacebased (Gaia) surveys. is a multi-object multi-IFU utilizing new 2 degree prime focus field view at WHT, with buffered pick place positioner system hosting 1000 (MOS) fibres or to 30 integral units each observation. The are fed single spectrograph, pair 8k(spectral) x 6k (spatial) pixel cameras,...
We combine all available information to constrain the nature of OGLE-2005-BLG-071Lb, second planet discovered by microlensing and first in a high-magnification event. These include photometric astrometric measurements from Hubble Space Telescope, as well constraints higher order effects extracted ground-based light curve, such microlens parallax, planetary orbital motion finite-source effects. Our primary analysis leads conclusion that host Jovian OGLE-2005-BLG-071Lb is an M dwarf foreground...
We discuss the selection and observations of a large sample nearby galaxies, which we are using to quantify star formation activity in local Universe. The consists 334 galaxies across all Hubble types from S0/a Im with recession velocities between 0 3000 km s-1. basic data for each galaxy narrow band H[Nii] R-band imaging, derive rates, equivalent widths surface brightnesses, total magnitudes. A strong correlation is found rate type, strongest isolated occurring Sc Sbc types. More...
We present the first microlensing candidate for a free-floating exoplanet–exomoon system, MOA-2011-BLG-262, with primary lens mass of Mhost ∼ 4 Jupiter masses hosting sub-Earth moon. The argument an exomoon hinges on system being relatively close to Sun. data constrain product MLπrel where ML is and πrel lens–source relative parallax. If nearby (large πrel), then small (a few masses) companion sub-Earth-mass exomoon. best-fit solution has large proper motion, μrel = 19.6 ± 1.6 mas yr−1,...
We present the first example of binary microlensing for which parameter measurements can be verified (or contradicted) by future Doppler observations. This test is made possible a confluence two relatively unusual circumstances. First, lens bright enough (I=15.6) to permit measurements. Second, we measure not only usual 7 binary-lens parameters, but also 'microlens parallax' (which yields mass) and components instantaneous orbital velocity. Thus measure, effectively, 6 'Kepler+1' parameters...
Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) measure distance Moon, baseline of Earth so small that can generally only be applied objects in Solar System. However, there exists a class extreme gravitational microlensing events which effects readily detected and permit measurement distance, mass, transverse velocity lens. Here we report observations...
We present the discovery and mass measurement of cold, low-mass planet MOA-2009-BLG-266Lb, performed with gravitational microlensing method. This has a mp = 10.4 ± 1.7 M⊕ orbits star M⋆ 0.56 0.09 M☉ at semimajor axis AU an orbital period yrs. The host measurements are enabled by parallax effect, which is seen primarily in light curve distortion due to motion Earth. But analysis also demonstrates capability measure Deep Impact (or EPOXI) spacecraft heliocentric orbit. distance similar...
ABSTRACT OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in binary black hole model. The model predicted major outburst 2015 December. We found the did occur within expected time range, peaking on December 5 at magnitude 12.9 R -band. Based Swift /XRT satellite measurements and polarization data, we find it included thermal component. Its timing provides an accurate estimate for spin of primary hole, . present also...