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Title: Optical transients in the WASP survey
Author: Marshall, George
ISNI:       0000 0004 2703 9191
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2010
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This thesis describes a search for transient phenomena using data from the Wide Angle Search for Planets (WASP) observatories. With images taken of the same region of sky every 15 minutes and a field-of-view of 974 degrees squared, the WASP survey is ideal for identifying both short and long duration transients to a limiting magnitude of 16 in V. A high cadence wide-field survey of this type has not been carried out before so provides a different method of sampling variable populations and has the potential to identify previously unknown phenomena. An algorithm to carry out a full untargeted search of the database was developed, tested and run on data from 2004, 2006, 2007 and 2008. False positives were rejected based on their proximity to similar magnitude stars, the tightness of the clustering of detections in sky coordinates, the focus of the images and the number of corroborating detections. Overall, 44 cataclysmic variable candidates, 144 extreme flare candidates, 63 variable star candidates and 57 transients of unknown type were identified. The cataclysmic variable candidates showed similarities to the currently known population although some selection effects were uncovered. Of particular note were two new WZ Sge systems, an eclipsing system with a period of 540 minutes and an object with an M-star spectrum and broad Balmer lines but no visible white dwarf. The flares are some of the largest ever observed on M-type stars. The largest of these released ~1035erg in the V-band alone. A candidate flare was also identified on a G-type star releasing 1.6×1037erg in the V-band. Alternatively, it may be unrelated to the G-star and could be a gamma ray burst or similar transient without a persistent counterpart. A known supernova and two known novae were also identified.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QB Astronomy