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Long-Term Time-Series Photometry in Cygnus

Miller, Niall (2021) Long-Term Time-Series Photometry in Cygnus. Master of Science by Research (MScRes) thesis, University of Kent,. (doi:10.22024/UniKent/01.02.90591) (KAR id:90591)


In this thesis we present the data reduction, database creation and photometric correction of a large, high cadence data-set provided by an amateur astronomer. We also discuss the potential science projects available from this data. The database and catalogue produced via the methods detailed in this report feature 19,858 stars within a 2.8 x 2.8 degree square centred on 317.0, +46.5 (J2000). Each star has ~ 64,000 measurements collected between 2003-09 to 2009-09. The final, photometrically corrected magnitudes have an approximate error of +/0 0.025 mag for bright stars and+/-0.040 mag for dimmer stars. The shortest cadence for the data is 1 minute (much of the data is spaced 1 minute apart with larger gaps due to nightly/seasonal observations). The data is 99% complete up to a magnitude of GAIA R ~15 mag and begins to saturate at a magnitude of GAIA R ~ 7 mag.

We have shown how the database was created with the intention of making light curves easy to retrieve. During this we also explored how certain features of the data-set, such as the seeing and resolution, were instrumental in the design features of the database, particularly when designing the software to match the same objects across multiple images.

We have also cross-matched the objects in this database with other publicly available databases such as GAIA, 2MASS and WISE in order to gain further information on the population present in this data-set. We may use the additional information provided by GAIA's astrometric data (parallax and proper motion) and stellar colour (provided by GAIA, 2MASS and WISE) to further investigate this stellar population.

We found that the flat frames used for calibration did not produce data of sufficient quality for accurate photometric measurements. A substantial amount of structure is present in some of the flat fields, as it is not possible to know if the structure is truly due to the optical path of the telescope or due to incorrect flat fielding methods. Hence, a photometric correction was performed. The correction procedure removed any systematic photometric offset caused by inhomogeneous flat frames. This was achieved with modelling the photometric offset in a given image that is present in non-variable stars. The model is a function of magnitude, colour and CCD position, and is subtracted from all stars in the image.

We have outlined some of the potential future science projects that can be performed with this data, and show that the database presented in this report is very good for conducting research in the field of time-based astronomy. A preliminary investigation of periodic variable stars was performed. It was found that multiple different types of periodic variables are present in our catalogue such as W Uma binaries and Delta Cepheids. We also investigated the possibility of detecting exoplanet transits and found that it is possible to obtain a photometric accuracy high enough to detect exoplanet transits at the sacrifice of temporal resolution. We found that, if we bin our data to reduce the temporal resolution to 42 minutes, we have a 90\% probability of detecting a hot Jupiter.

Item Type: Thesis (Master of Science by Research (MScRes))
Thesis advisor: Froebrich, Dirk
DOI/Identification number: 10.22024/UniKent/01.02.90591
Uncontrolled keywords: astronomy, astrophysics, time-series, temporal-astropysics, data-reduction, photometry
Subjects: Q Science > QB Astronomy
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
SWORD Depositor: System Moodle
Depositing User: System Moodle
Date Deposited: 05 Oct 2021 09:10 UTC
Last Modified: 23 Dec 2022 04:33 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Miller, Niall.

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