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Sean O'Brien

I'm Sean (he/him), an MSc student in the Astronomy and Astrophysics group at the University of Warwick under the supervision of Dan Bayliss. I completed my BSc in Mathematics at Warwick (2017-2020).


My research is as part of the Exoplanets Group. Specifically, I use NGTS photometry to analyse the light curves of bright stars in order to study the scintillation effect. Atmospheric scintillation is caused by light passing through turbulent regions of the Earth's atmosphere, resulting in changes in intensity of the light received by a telescope. This is more colloquially known as the "twinkling" we see when observing stars with the naked eye. This is the dominant noise source when observing bright stars with small-aperture ground-based telescopes, such as at the NGTS observatory at Paranal, Chile. I am comparing the approximations of the modified Young's equation for scintillation noise with measurements made by atmospheric site monitors such as the MASS-DIMM at Paranal. Primarily, I am measuring the empirical coefficient, CY, which captures the mean scintillation conditions at observatories. I also analyse the variation in scintillation compared with factors such as high-altitude turbulence and wind velocity, including the seasonal variation in the position and speed of the jetstreams. Additionally, I am testing the precision of the NGTS cameras by comparing scintillation measurements from multi-telescope observations. I primarily use Python, including the SciPy, Matplotlib, pandas and AstroPy packages.

The following animation shows the wind velocity vectors (black arrows) and wind speed contours over South America (blue outline) for the months of January 2016 through to April 2021. The red star indicates the position of Paranal Observatory. These plots are generated from ECMWF data and are used to study high-altitude wind speeds, typically dictated by the position and strength of the jet stream. The differences in wind speed throughout the year have differing effects on long-exposure and short-exposure scintillation.

Gif showing the wind speed vectors and contours above South America for each month since January 2016 to April 2021

Outreach and other interests

In 2019, I completed a month-long internship as a Maths/Physics Teaching Assistant in a top UK secondary school, working with students between ages 11-18 of varying abilities including those with Special Educational Needs. I hope to use my experience gained during the internship and apply it to outreach activities run by Warwick, as well as any future opportunities for teaching others about astronomy, physics or maths.


I've been a cyclist for around 8 years, racing competitively since 2016. If I'm not at my desk, I'm riding my bike! (Eddington number of 61)

University of Warwick Triathlon & Road Cycling Club:

Running & Duathlon Coordinator (2018-19); Social Secretary (2020-21). I am a regular attendee of club cycle rides and races, competing in both BUCS events and local races as well as organising registration and transport for the team on occasion.

Picture of Sean

Write to:

Sean O'Brien,
Department of Physics,
University of Warwick,
Coventry CV4 7AL

Contact details:

Office: PS0.16C