Planet Hunters NGTS: A citizen science search with the Next Generation Transit Survey

When an exoplanet transits (passes in front of) its host star, a portion of the star's light is blocked, resulting in a characteristic dimming that can be measured from Earth. Today we know of over 4000 transiting planets/planet candidates. The Next Generation Transit Survey (NGTS) consists of twelve automated 20cm telescopes working in tandem to monitor the night sky. Observing since 2015, the survey has produced a rich dataset to probe stellar variability and search tens of thousands of stars for the signatures of transiting exoplanets. NGTS applies automated algorithms to identify transiting exoplanet candidates that are then reviewed and vetted by science team inspection. This process involves a large number of false positives and potential biases created by the small number of reviewers. Citizen science projects such as Galaxy Zoo and Planet Hunters have demonstrated that analysis tasks performed by large numbers of non-expert volunteers are of value, with the crowd-sourced assessments outperforming the majority of automated routines and machine learning algorithms.

This PhD project aims to search for transiting exoplanet signals that may have been missed in the initial NGTS search. The public are enlisted to help in this search via a website where they are tasked with inspecting several characteristic plots from stars identified from the NGTS algorithmic search. The Planet Hunters NGTS project(https://ngts.planethunters.org) launched in October 2021. The main aim of the PhD project is to analyse the results from this brand-new citizen science project, developing a software pipeline to combine the multiple volunteer classifications together and identifying the most promising planet candidates. The project will also involve measuring the detection efficiency of the project, by comparing the results with expert classifications and using simulated planet transits. We expect that a component of this project will involve performing, analysing, and interpreting observational data from optical ground-based telescopes to validate and characterise discoveries from the NGTS citizen science project.