Roy David Williams

roy at

My work now focuses on providing people with meaningful access to scientific and technical data, as well as learning from, making decisions from, and preserving that data.

My career began with a degree in mathematics from Cambridge, then a PhD in nuclear physics and mathematical physics at Caltech. I was proud to work with Nobel-prizewinner Willy Fowler (paper), and I think my co-workers and I were first to work on nuclear pasta (paper).

I worked in physics a few more years, then worked with the new architecture computers, rebuilding scientific simulation codes for parallel machines, and making new codes with unstructured meshes and dynamic load balancing (see 1993 below). I was co-author of a book Parallel Computing Works!. There was a lot of fluid-flow simulation on parallel computers, inculuding a simulation of the hypersonic flow around the Huygens space probe that landed on Saturn's moon Titan (paper).

The world-wide web arrived in the early 1990's, where I was an early adopter. In 1995, I gave a lecture and wrote an article about its potential. I was building web applications in 1996, delivering Earth remote-sensing data over the internet, where I wrote about what I called Hypermaps, a prequel to Google Maps.

I worked with the LIGO (gravitational waves) project in the late 1990's, introducing them to databases and XML, and built science gateways for the US Teragrid project. I was with the Virtual Observatory from the start, as architect, also creating in large part the VOTable and VOEvent standards, now widely used. There was a lot of work on astronomical transients, leading up to the Palomar Transient Factory and preliminary work on LSST, realizing that soon the transient detections would overwhelm the ability of telescopes to observe them all. I worked again for the LIGO group from 2010, developing the Gravitational Wave Open Science Center. I was lucky enough to be at Caltech when the first detection happened, with all its excitement, and I wrote this account of LIGO is Awesome and This is Why.

In June 2017 I moved to Edinburgh, where I work at the Royal Observatory, where I work in preparation for the flood of transient observations from the LSST telescope, due to be on sky in 2020. There are expected to be millions of transient observations per night, and we are preparing by building a prototype called Lasair at

Edinburgh is a great place to live. I am enjoying spending a day each week at the Edinburgh Tool Library in Colinton, and listening to the wind blowing outside my office window at the Observatory. Also starting to do a bit of writing.


Paintings 2019 and beyond

Stellations of the Icosahedron


Stained glass

Javascript games.

Useless information about Pi

Xmorphia: beautiful equations

Paintings of Vermeer: ancient pages from 1995

Greatstreets: 47 city street plans to scale



Enabling Science from the Rubin Alert Stream with Lasair
Roy D. Williams, Gareth P. Francis, Andy Lawrence, Terence M. Sloan, Stephen J. Smartt, Ken W. Smith, David R. Young
Click for arxiv.


NEural Engine for Discovering Luminous Events (NEEDLE): identifying rare transient candidates in real time from host galaxy images
X. Sheng et. al.
Click for arxiv.

GW190425: Pan-STARRS and ATLAS coverage of the skymap and limits on optical emission associated with FRB190425
S. J. Smartt et. al.
Click for arxiv.

Fitting Early light curves of Explosive Astrophysics
R. D. Williams
Click for pdf.


Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo Abbott et. al. (LIGO collaboration)
submitted to Nature Scientific Data Click for Arxiv and pdf.

Lasair: The Transient Alert Broker for LSST:UK Ken Smith, Roy D. Williams, D. R. Young, A. Ibsen, S. J. Smartt, A. Lawrence, D. Morris, S. Voutsinas, and M. Nicholl
Research Notes of the AAS, Volume 3, Number 1 Click here.


GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
LIGO Scientific Consortium
Phys. Rev. Lett. 119, 161101.


Observation of Gravitational Waves from a Binary Black Hole Merger
LIGO Scientific Consortium
Phys. Rev. Lett. 116, 061102


LIGO Open Science Center: data releases from the LIGO project. 2013 - present.

LIGO Data Management Plan Stuart Anderson and Roy Williams, 2013
Click here.


Responding to the Event Deluge Roy D. Williams, Scott D. Barthelmy, Robert B. Denny, Matthew J. Graham, John Swinbank
Proceedings of SPIE Observatory Operations, Amsterdam, 2012 Click here.

Community Input for LIGO Open Data edited by Roy Williams, Christian Ott, Steve Groom, 2012
Click here.

Astronomy with Cutting-Edge ICT: From Transients in the Sky to Data over the Continents (India-US) Ashish Mahabal, Ajit Kembhavi, Roy Williams and Sharmad Navelkar
Click here.


Gravitational Waves and Time-Domain Astronomy Joan Centrella, Samaya Nissanke and Roy Williams
Proceedings of the International Astronomical Union / Volume 7 / Symposium S285 / September 2011, pp 191-198 Click here.

Using the VO to Study the Time Domain Rob Seaman, Roy Williams, Matthew Graham and Tara Murphy
Proceedings of the International Astronomical Union / Volume 7 / Symposium S285 / September 2011, pp 221 - 226
Click here.


Skyalert: authoring, dissemination, annotating, mining, and messaging of immediate astronomical events. 2009 - 2013.

Sky Event Reporting Metadata (VOEvent)
R. Seaman, R.D. Williams, A. Allan, S. Barthelmy, J. Bloom, M. Graham, F. Hessman, S. Marka, A. Rots, C. Stoughton, T. Vestrand, R. White, P. Wozniak,
A Recommendation of the International Virtual Observatory Alliance, 2006. HTML

First Results from the Catalina Real-time Transient Survey
A.J. Drake, S.G. Djorgovski, A. Mahabal, E. Beshore, S. Larson, M.J. Graham, R. Williams, E. Christensen, M. Catelan, A. Boattini, A. Gibbs, R. Hill, R. Kowalski, Astrophysical J. 696 (2009) 870. PDF


National Virtual Observatory Summer School 2008
Roy Williams, Faculty Chair
Organized the content and teaching for a two-week intensive course on the Virtual Observatory, September 2008, Santa Fe, New Mexico.

VIM: Visual Integration and Mining
Integrate data from multiple positions and datasets.

Skyalert: Real-time Astronomy for You and Your Robots
R. D. Williams, S. G. Djorgovski, A. J. Drake, M. J. Graham, A. Mahabal.
Proc. ADASS XVIII (2008), PASP, eds. D. Bohlender, P. Dowler and D. Durand link

Describing Data and Data Collections in the VO
Kent, B.R.; Hanisch, R.J.; Williams, R.D.
in The National Virtual Observatory: Tools and Techniques for Astronomical Research, eds. Graham M.J., Fitzpatrick M.F., McGlynn T.A. ASP Conference Proceedings, vol. 382. PDF

Data-Intensive Computing in the 21st Century Ian Gorton, Paul Greenfield, Alex Szalay, Roy Williams
Computer 05/2008; DOI:10.1109/MC.2008.122 Click here.


Transient Event Reporting and Response with VOEvent
Seaman, R.; Allan, A.; Williams, R.
Astronomical Data Analysis Software and Systems ASP Conference Series, Vol. 394, Eds R.W. Argyle, P.S. Bunclark, and J.R. Lewis., p.213 (2007) PDF

The IVOA in 2007: Assessment and Future Roadmap
Roy Williams and the IVOA Technical Coordination Group
International Virtual Observatory Alliance, PDF

Google Sky mashup
Roy Williams and Andrew Drake
Real-time display of events from multiple streams. 2007. (bring up the Google Earth/Sky client, click Current Sky Events and VOEventNet)., or click here.


Astronomical network event and observation notification
White R.R., Allan A., Barthelmy S., Bloom J., Graham M.J., Hessman F.V., Marka S., Rots A., Scholberg K., Seaman R., Stoughton C., Vestrand W.T., Williams R., Wozniak P.R.,
Astronomische Nachrichten, 327 (2006) 775.

Object detection in multi-epoch data
G. Jogesh Babu, Ashish Mahabal, S. G. Djorgovski, R. Williams
Statistical Methodology, Volume 5, Issue 4, p. 299-306. PDF

The IVOA in 2006: Assessment and Future Roadmap
Roy Williams and the IVOA Technical Coordination Group
International Virtual Observatory Alliance, PDF.


HotGrid: Graduated Access to Grid-Based Science Gateways
Williams, R. Steenberg, C. Bunn, J. Lect. Notes Computer Sci. 3470 (2005) 78. PDF

The IVOA in 2005: Assessment and Future Roadmap
Roy Williams and the IVOA Technical Coordination Group
International Virtual Observatory Alliance, PDF

Virtual Observatory: From Concept to Implementation
S. G. Djorgovski and R. Williams
In: Science with Wavelengths on Human Scales, ASPCS, vol. 3xx. ASPCS PDF


VOTable Format Definition
Francois Ochsenbein, Roy Williams, Clive Davenhall, Daniel Durand, Pierre Fernique, David Giaretta, Robert Hanisch, Tom McGlynn, Alex Szalay, Mark B. Taylor, Andreas Wicenec,
A Recommendation of the International Virtual Observatory Alliance. HTML

An IVOA Standard for Unified Content Descriptors
S. Derriere, N. Gray, R. Mann, A. Preite Martinez, J. McDowell, T. Mc Glynn, F. Ochsenbein, P. Osuna, G. Rixon, R.D. Williams.
A Recommendation of the International Virtual Observatory Alliance. HTML


Multi-Wavelength Image Space: Another Grid-Enabled Science
Roy Williams, Bruce Berriman, Ewa Deelman, John Good, Joseph Jacob, Carl Kesselman, Carol Lonsdale, Seb Oliver, Tom Prince
Concurrency & Computation, vol 15 (2003), pp 539-549. PDF,

Grids and the Virtual Observatory
Roy Williams
in Grid Computing: Making The Global Infrastructure a Reality by Fran Berman, Anthony J.G. Hey, and Geoffrey Fox, Wiley, 2003, pp 837-858. PDF


Scientific Data Mining Integration and Visualization
Bob Mann, Roy Williams, Malcolm Atkinson, Ken Brodlie, Amos Storkey, Chris Williams,
report of a workshop held in Edinburgh, 24-25 October 2002. PDF

XML and Web Services for Astronomers
Roy Williams and Robert Brunner
tutorial at ADASS 2002, Baltimore, October 2002. PPT

Network data analysis server (NDAS) prototype development
Szabi Marka, Benoit Mours, Roy Williams
Classical and Quantum Gravity 19 (7): 1537-1540 (2002)

Agent based data management in digital libraries
Y.Y. Yang, O.F. Rana, D. W. Walker, R. D. Williams
Parallel Computing 28 (5): 773-792 (2002)


Analysis of Shear Layers in a Fluid with Temperature-Dependent Viscosity
D. J. Estep, S. M. Verduyn Lunel, and R. D. Williams
J. Comp. Physics, vol 173 (2001), pp 17-60. PDF

Web access to supercomputing
G. Aloisio, M. Cafaro, C. Kesselman, R. Williams
Computational Science and Engineering 3 (6): 66-72 (2001)

A Virtual Data Grid for LIGO
Ewa Deelman, Carl Kesselman, Roy Williams, Albert Lazzarini, Thomas A. Prince, Joe Romano and Bruce Allen
Lecture Notes in Computer Science, vol 2110 (2001) pp 3-12


Estimating the Error of Numerical Solutions of Systems of Nonlinear Reaction-Diffusion Equations

The Formation, Structure, and Stability of a Shear Layer in a Fluid with Temperature-Dependent Viscosity D. J. Estep, S. M. Verduyn Lunel, and R. D. Williams
June 2000

D. J. Estep, M. G. Larsen, and R. D. Williams
Memoirs Amer. Math. Soc., 146 (2000) number 696, pp 1-109. PDF

A Test Suite for High-Performance Parallel Java
Jochem Hauser, Thorsten Ludewig, Roy Williams, Ralf Winkelmann, Torsten Gollnick, Sharon Brunett, Jean Muylaert
Advances in Engineering Software 31 (8-9): 687-696 (2000)

Grid computing on the web using the globus toolkit
G. Aloisio G, M. Cafaro, P. Falabella, R. Williams
Lecture Notes in Computer Science 1823: 32-40 (2000)

Approaches to Federation of Astronomical Data
Roy Williams
in Virtual Observatories of the Future, eds. R. J. Brunner, S. G. Djorgovski, and A. S. Szalay, Astronomical Society of the Pacific, Conference Series 225. November 2000. PDF


Special issue: Interfaces to Scientific Digital Archives
ed. Roy Williams
Future Generation Computer Systems 16 (1): VII-VIII (1999)

The Digital Puglia Project: An active digital library of remote sensing data
G. Aloisio, M. Cafaro, R. Williams
Lecture Notes in Computer Science 1593: 563-572 (1999)

An XML Architecture for High-Performance Web-Based Analysis of Remote-Sensing Archives
Giovanni Aloisio, Giovanni Milillo, and Roy Williams
Future Generation Computing Systems 16 (1): 91-100 NOV 1999. PDF.

Strategies for Parallel and Numerical Scalability of CFD Codes
Ralf Winkelmann, Jochem Hauser and Roy Williams
Computational Methods in Applied Mechanical Engineering. 174 (3-4): 433-456 (1999). PDF
(image shows Huygens craft, that landed on Titan Jan 2004)

A Pure Java Parallel Flow Solver
Jochem Hauser, Thorsten Ludewig, Torsten Gollnick, Ralf Winkelmann, Roy Williams, Jean Muylaert, and Martin Spel
AIAA paper 99-0549, proceedings of 37th Aerospace Sciences Meeting, Reno NV, Jan 1999.

XSIL: Extensible Scientific Interchange Language
Kent Blackburn, Albert Lazzarini, Tom Prince and Roy Williams
Lect. Notes. Comp. Sci. 1593 (1999) 513.


Report of the European Union - United States Workshop on Large Scientific Databases
Roy Williams, Paul Messina, Fabrizio Gagliardi, John Darlington, and Giovanni Aloisio
October 1999

Interfaces to Scientific Data Archives
Report of the NSF Workshop
Roy Williams, Julian Bunn, Reagan Moore and James Pool,
May 1998. HTML .

Paraflow: A dataflow distributed data-computing system
Roy Williams and Bruce Sears
Lecture Notes in Computer Science 1401: 556-565 (1998)

Metacomputing - From ideas to real implementations
Wolfgang Nagel and Roy Williams
Parallel Computing 24 (12-13): 1709-1711 (1998)


A Distributed Web-based Metacomputing Environment
G. Aloisio, M. Cafaro, P. Messina, R. D. Williams,
in HPCN97, Vienna, April 1997. PDF

A Tangled Web Strategy for Numerical and Parallel Scalability in Aerospace Simulation
J. Haeuser, R. D. Williams and R. Winkelmann
Proceedings of CFD97, University of Victoria, Canada, 25-27 May 1997. PDF.


Dreaming of Hypermaps
Caltech Engineering and Science magazine, PDF.

Video: Letter R formed by evolution of non-uniform Gray-Scott model, 1999. Click here.

Error Estimation for Numerical Differential Equations
D. J. Estep, S. M. Verduyn Lunel and R. D. Williams
IEEE Antennas and Propagation 38 (2): 71-76 (1996). PDF

Accurate Parallel Integration of Large Sparse Systems of Differential Equations
D. J. Estep and R. D. Williams
Mathematical Models and Methods in Applied Sciences 6 (4): 535-568 (1996). PDF

Efficient Convergence Acceleration for Parallel CFD Codes
R.D. Williams, J. Hauser and R. Winkelmann,
Proceedings of the Parallel CFD '96 conference, Capri, Italy
July 1996. PDF


"Infinite" Information on the Internet
Caltech Engineering and Science magazine PDF

A Newton-GMRES Method for the Parallel Navier-Stokes Equations
J. Hauser, R.D. Williams, H.-G. Paap, M. Spel, J. Muylaert and R. Winkelmann
Proceedings of the Parallel CFD '95 conference, Pasadena, California
July 1995. PDF


Parallel Computing Works!
G. C. Fox, R. D. Williams and P. C. Messina,
Morgan-Kaufmann, San Francisco, 1994 (available from Amazon)


Unstructured hypersonic flow on a parallel machine

These pictures show a parallel 3D adaptive unstructured mesh. The first two images show the pressure on the outside of a pipe of square cross section, that has a slot in it. Fluid moves from the top right to the bottom left; the main bow shock is reflected multiple times as the fluid moves down the pipe. The third image shows the surface of the unstructured tetrahedral mesh that was used for the computation; the mesh has self-adapted to the pressure gradient, meaning a finer mesh at the shocks. The fourth picture shows the decomposition of the mesh among 512 parallel processors: each colour represents a differentr processor. Adaptivity is evident here also, as each processor has an equal number of tetrahedral mesh cells.


Strategies for Parallelizing a Navier-Stokes Code on the Intel Touchstone Machines
J. Häuser and R. D. Williams,
Int. J. Numerical Methods in Fluids, 15, 51 (1992)

Voxel Databases: A Paradigm for Parallelism with Spatial Structure
R. D. Williams,
Concurrency, 4 (1992) 619. PDF


Adaptive Parallel Meshes with Complex Geometry
R. D. Williams
in Numerical Grid Generation for Computational Fluid Dynamics, ed. A.-S. Arcilla et. al., Elsevier North-Holland, Amsterdam, 1991. PDF

Performance of Dynamic Load Balancing Algorithms for Unstructured Mesh Calculations
R. D. Williams,
Concurrency, 3 (1991) 457. PDF

Adaptive Parallel Meshes with Complex Geometry
C. F. Baillie, R. D. Williams, S. M. Catterall and D. A. Johnston
Nucl. Phys B348, 543 (1991)

Performance of Dynamic Load Balancing Algorithms for Unstructured Mesh Calculations
R. D. Williams,
Concurrency, 3, 457 (1991) PDF users manual


Benchmarking Advanced Architecture Computers
P. Messina, C. F. Baillie, E. W. Felten, P. G. Hipes, D. W. Walker, R. D. Williams, et al,
Concurrency, 2, 195 (1990)

Crumpling Transition in Dynamically Triangulated Random Surfaces
C. F. Baillie, R. D. Williams, D. A. Johnston
Nuclear Physics B 335 (2): 469-501 (1990)

Computational Aspects of Simulating Dynamically Triangulated Random Surfaces
C. F. Baillie, R. D. Williams, D. A. Johnston
Computer Physics Communications 58 (1-2): 105-117 (1990)


Distributed Irregular Finite Elements
R. D. Williams
A software package for distributed parallel computing with unstructured triangular and tetrahedral meshes. PDF users manual

Supersonic Flow in Parallel with an Unstructured Mesh
R. D. Williams
Concurrency, 1, 51 (1989) PDF.


Free-Lagrange Hydrodynamics in Parallel
R. D. Williams
Parallel Computing 7, 439 (1988) PDF.


Two Transitions in Tangentially Anchored Nematic Droplets
R. D. Williams
J. Phys. A19, 3211 (1986) PDF

Critical Spin Dynamics of Europium Oxide
S. W. Lovesey and R. D. Williams
J. Phys. C19, L253 (1986)

Scattering Response of a Phonon Damped Harmonic Oscillator
R. D. Williams, S. W. Lovesey and W. Renz,
Z. Physik B64, 129 (1986) PDF

Neutron Scattering from a Substitutional Mass Defect
R. D. Williams and S. W. Lovesey
Z. Physik B62, 413 (1986) PDF


Sub-Saturation Phases of Nuclear Matter
R. D. Williams and S. E. Koonin,
Nucl. Phys. A345, 844 (1984) PDF

Bound-State Decay of Rhenium-187
R. D. Williams, W. A. Fowler and S. E. Koonin,
Astrophys. J. 281, 363 (1984) PDF


Semiclassical Quantization in Many Dimensions
R. D. Williams,
Ph.D. Thesis, California Institute of Technology, 1983

The Coupling of Phonons to a Helium Atom Adsorbed on Graphite
R. D. Williams, M. W. Cole and S. E. Koonin,
Phys. Rev. B28, 1076 (1983)

Atomic Final-State Interactions in Tritium Decay
R. D. Williams and S. E. Koonin,
Phys. Rev. C27, 1815 (1983) PDF


Semiclassical Quantization of the Shell Model
R. D. Williams and S. E. Koonin,
Nucl. Phys. A391, 79 (1982) PDF


Direct Capture Cross Sections at Low Energy
R. D. Williams and S. E. Koonin,
Phys. Rev. C23, 2773 (1981) PDF