Open Research Online The Open University’s repository of research publications and other research outputs PIRATE: A Remotely Operable Telescope for Research and Education Thesis How to cite: Holmes, Stefan (2013). PIRATE: A Remotely Operable Telescope for Research and Education. PhD thesis The Open University. For guidance on citations see FAQs. c 2013 The Author https://creativecommons.org/licenses/by-nc-nd/4.0/ Version: Version of Record Link(s) to article on publisher’s website: http://dx.doi.org/doi:10.21954/ou.ro.0000f118 Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online’s data policy on reuse of materials please consult the policies page. oro.open.ac.uk PIRATE: A Remotely Operable Telescope for Research and Education Stefan Holmes MPhys Supervisors : Dr. Ulrich Kolb, Dr. Carole Haswell PhD thesis submitted for the degree of Doctor of Philosophy Department of Physical Sciences, The Open University Submitted September 2012 ProQuest Number: 13835950 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 13835950 Published by ProQuest LLC(2019). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 Abstract This thesis introduces PIRATE, a remotely operable telescope facility for use in research and education, constructed from off-the-shelf hardware, operated by the Open University. It focuses on the PIRATE Mark 1 and PIRATE Mark 1.5 phases of operation; the telescope facility has been in the Mark 2 phase since September 2011. Situated at the Observatori Astronomic de Mallorca, PIRATE is currently used to follow up poten­ tial transiting extrasolar planet candidates produced by the SuperWASP North experiment, as well as to hunt for novae in M31 and other nearby galaxies. It is operated by a mixture of commercially available software and proprietary software. In this thesis I discuss the hardware and its characterisation, problems with performing precision time-series photom­ etry when using a German Equatorial Mount, and the PIRATE pipeline developed to assist with the fast and effective production of results from the follow-up observations of potential transiting extrasolar planets. I then go on to discuss the logistics of the follow-up program, and present the results from the PIRATE Mark 1 and 1.5 follow-up data, followed by the results from observational work on known transiting systems (such as WASP-12b). A discussion of areas for improvement and possible avenues for future work concludes the thesis. I w The Library d o n a t i o n Dedicated to my beautiful fiancee Kit for her boundless love and support. Acknowledgements I would firstly like to thank my supervisors Ulrich Kolb and Carole Haswell for all their efforts and assistance over the last few years. I couldn’t have wished for better supervision; they did a sterling job of tempering my more tangential tendencies and always focused my attentions in the most profitable directions. My sincere thanks to you both. I would also like to thank the PIRATE team and all of the contributors to the project: Ulrich for running the show, Vadim Burwitz, Rob Lucas, Juan Rodriguez, Jaume Andreu and all the staff at the OAM, other colleagues who have worked on the project at one time or another: Samantha Rolfe, John Barker, John Rostron; and my current colleagues now working on the project: Richard Busuttil and Jakub Bochinski - I leave it in safe hands. Contents 1 Introduction 1 1.1 The PIRATE project ...................................................................................... 1 1.1.1 Use in e d u c a tio n ................................................................................. 2 1.1.2 Use in re s e a rc h .................................................................................... 3 1.1.3 The O A M .............................................................................................. 4 1.1.4 Other similar fa c ilitie s ....................................................................... 5 1.1.5 Thesis sum m ary .............................................................................. 6 1.2 Exoplanets and their discovery ......................................................... 7 1.2.1 Brief history of exoplanet s c ie n c e ................................................... 7 1.2.2 Methods of detecting exoplanets ........................................................ 9 1 .2 .2.1 Astrometry ................................................................. 10 1.2.2.2 Gravitational lensing ........................................................ 11 1.2.2.3 Radial velocity measurements ................................ 12 1.2.2.4 T ra n s its ....................................................................... 15 1.2.2.5 Transit timing variations .......................................... 16 1.2.3 The transit m e th o d ............................................................................. 16 1.2.3.1 Transit duration ....................................................... 17 1.2.3.2 The shape of the transit light curve ...................... 19 1.2.3.3 Fraction of stellar disc occulted as a function of time 21 1.2.3.4 Limb darkening .......................................................... 25 1.2.3.5 Determining system parameters from the transit light curve ................................................................................... 27 2 PIRATE Hardware Software 29 2.1 The PIRATE hardware and its evolution .................................................. 29 2.1.1 Primary hardw are ................................................................................ 29 2 .1.2 Ancillary hardware ............................................................... 32 i 2.2 PIRATE softw are .............................. 32 2.2.1 Maxim DL .......................................................................................... 35 2.2.2 TheSky 6 ................................................................................................ 35 2.2.2.1 The pointing model ......................................................... 35 2 .2 .2.2 Periodic Error Correction (P E C ) .................................. 36 2.2.3 F o cu sM ax ............................................................................................. 36 2.2.3.1 V -curves ................................................................................ 38 2.2.3.2 The auto-focus procedure ............................................... 38 2.2.4 A C P ....................................................................................................... 41 2.2.4.1 Web s e r v e r ......................................................................... 41 2 .2.4.2 Observing plans ......................................................................42 2 .2 .4.3 Automatic sky flat acquisition ......................................... 44 2 .2.4.4 Initial pointing, pointing updates .................... 47 2.2.4.5 A utoguiding ......................................................................... 47 2.2.4.6 Weather monitoring and safety sh u td o w n s.................. 49 2.2.4.7 File organisation and indexing ......................................... 50 2.2.5 Weather software ................................................................................ 51 2.2.5.1 The Boltwood cloud sensor II & Clarity II software . 51 2.2.5.2 Weather32 / Reinhardt weatherstation ........................ 53 2.2.5.3 Heavy W e a th e r ................................................................... 54 2.3 Hardware ch aracterisatio n ............................................................................ 54 2.3.1 Camera ch aracteristics ...................................................................... 54 2.3.2 Flat-held inacuracy and optical response calibration ................... 57 2.3.3 Investigation of PIRATE Mark 1.5 data ...................................... 62 3 PIRATE Light Curve Generation 69 3.1 Photometric precision and sources of uncertainty ....................................... 69 3.1.1 Making a photometric measurement ............................................... 69 3.1.2 The CCD equation ............................................................................. 73 3.1.3 Correlated noise ......................................................................... 74 3.2 The PIRATE data reduction p ip e lin e ......................................................... 75 3.2.1 Pipeline operation ............................................................................. 76 3.2.1.1 Calibrating the science images ......................................... 76 3.2.1.2 Performing the aperture photom etry ............................ 77 3.2.1.3 Producing the final light curves ...................................... 79 3.3 Optimal ensemble compilation ...................................................................... 80 ii 3.3.1 How the pipeline computes final light curves ............................... 80 3.3.2 Optimal ensemble