Ireland’s key role in Veritas Astrophysics project

The gamma-ray instrument at the Smithsonian Institution’s Fred Lawrence Whipple Observatory in southern Arizona, USA.

John Daly talks to CIT physicist Dr Paul Reynolds about the Veritas project.

Veritas — the Very Energetic Radiation Imaging Telescope Array System — is an international astrophysics collaboration between the USA, Canada, Germany and Ireland (UCD, NUIG and CIT).

The project involves nine founding institutions and 15 collaborating institutions.

It operates a ground-based gamma-ray instrument at the Smithsonian Institution’s Fred Lawrence Whipple Observatory in southern Arizona, USA — an array of four 12m optical reflectors that uses the Imaging Atmospheric Cherenkov technique to perform gammaray astronomy in the GeV — TeV energy range.

High-energy gamma rays are associated with exotic cosmic objects such as exploding stars, or supernovae, pulsars, quasars and black holes.

Expensive, space-based observatories are normally required to detect gamma rays as they are absorbed in the atmosphere, but VERITAS is able to use the Atmospheric Cherenkov Imaging technique to observe them from the ground.

“Ireland has had an important role in this going way back to the 1960s when the actual technique was discovered by an Irish American scientist, Neil Porter, who was a professor in UCD,” explains Dr Paul ‘Josh’ Reynolds, CIT Department of Physical Sciences.

“He set up in the Wicklow mountains with a series of searchlights and started the Atmospheric Cherenkov Imaging technique, and led through to the breakthrough discovery in this area of astronomy in 1987. It consisted back then of a small group of Irish and American scientists, but which has over the years mushroomed into a number of observatories.”

Dr Reynolds highlights the major project currently underway — the Cherenkov Telescope Array (CTA), the next generation ground-based observatory for gamma-ray astronomy at very-high energies.

With more than 100 telescopes located in the northern and southern hemispheres, CTA will be the world’s largest and most sensitive high-energy gamma-ray observatory.

“This will hopefully come on line in three or four years time and is where the knowledge gleaned over the years will be put into.”

The southern array will be hosted in Chile‘s Atacama Desert, and the northern at La Palma in Spain.

Dr Paul ‘Josh’ Reynolds, CIT Department of Physical Sciences, who is playing a lead role in the international VERITAS astrophysics project.
Dr Paul ‘Josh’ Reynolds, CIT Department of Physical Sciences, who is playing a lead role in the international VERITAS astrophysics project.

“With one on either side of the equator, it will allow for full coverage of the sky,” he said. “This is an enormous project, with thousands of scientists involved.”

Dr Reynolds has been a member of the VERITAS collaboration ever since its inception back in 2003, as well as being a member of its progenitor — the Whipple Observatory collaboration. He is also a co-author of the publication that announced the discovery the Atmospheric Cherenkov Imaging Technique in 1989.

“My participation to-date in VERITAS has been funded with Basic Research Grants from Science Foundation Ireland, with some contributions from CIT, but funding for this class of basic Astronomy research has been discontinued by SFI since 2012,” Dr Reynolds said.

“VERITAS has a prodigious research output, with approximately 90 publications in peer reviewed journals over the last eight years.”

CIT hosted the VERITAS summer collaboration meeting in 2010. “I was responsible for installing and currently run and maintain two of the atmospheric quality monitoring systems at the VERITAS, namely a LIDAR and a network of Mid-IR radiometers.

"The LIDAR system was purchased by CIT through a Science Foundation Ireland Research Frontiers Programme grant in spring 2011 and was deployed at VERITAS after a six month testing period at Blackrock Castle.”

Each collaboration member is required to spend at least two weeks on-site, in the period from September to June, taking data and performing engineering work with the instrument.

“My most recent research visit was a two-week tour of duty in January 2018 when I was one of a three-man team taking data with the VERITAS instrument and performed maintenance and calibration on the CIT sourced atmospheric monitoring instrumentation. Results from data taken on the gamma ray blazar TXS 0506+056 during this observing campaign was published as part of The ICE-CUBE neutrino emission discovery from the same source.”

Dr Reynold’s next research visit to VERITAS is scheduled to take place in June/July 2019. Data from the instrument has been used in multiple level 8 projects over the years in CIT – last semester a Maths Department Data Analytics student performed deep learning on the raw images and his project achieved joint top project marks in the class.

The VERITAS collaboration is bound by a teaming agreement between nine founding institutions and 15 collaborating institutions, of which CIT is one. “I was elected as one of the two collaborator representative member of the 12 person VERITAS Executive Committee (VEC) for two years between Spring 2016 – Spring 2018.”

The VEC is a supervisory and regulatory body for the project that determines membership of the VERITAS collaboration, advises the project office on budgetary and policy matters, defines appoints and reviews committees, reviews and approves proposals pertaining upgrades to the VERITAS instrument and for additional instruments relating to the VERITAS site.

“I was a graduate student and had joined the research group in UCD back in 1985, working for a year with the Smithsonian when the discovery was made. That was probably the most exciting time, but there have been others along the way that have made it quite a memorable journey to be part of.”

Dr Reynolds says the current VERITAS spokesman is Irish — the recently elected Professor John Quinn.

Further information on the VERITAS experiment are available at

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