Jagiellonian University Doctoral Thesis Towards advanced astronomical imaging: new techniques of data reduction and their applications Author: Supervisor: Aleksander Kurek Dr hab. Agnieszka Pollo A thesis submitted in fulllment of the requirements for the degree of Doctor of Philosophy in the Faculty of Physics, Astronomy and Applied Computer Science 30 marca 2017 ii I’ve seen things you people wouldn’t believe. Attack ships on re o the shoulder of Orion. I watched C-beams glitter in the dark near the Tannhäuser Gate Roy Batty iii Abstract Goal The main goal of this thesis is to present new advanced methods of data acquisition and reduction developed in order to increase the photometric eciency and angular resolution of astronomical imaging. Methods I present an overview of the techniques I developed during my PhD studies. They include: (1) increasing the precision of bad pix- els removal, (2) impulse noise removal, (3) precise photometry and high angular resolution imaging of extremely faint sources, (4) ef- cient exposure times planning and (5) superresolved imaging of extended distant sources. Results It was shown that (1) is is possible to interpolate over bad pixels in the CCD ∼4× more eciently than it is done by standard meth- ods. A review of impulse noise removal techniques demonstrated (2) that the standard method (Laplacian Edge Detection) is in most cases the most ecient one, however, there are exceptions – mainly astrometric applications. Our evolutionary algorithm-based meth- ods were shown to be able to: (3) recover the surface prole of sources which are only ∼2-3 % stronger than their background; and (4) nd an optimal way to divide the available observing time to multiple exposures, so that the average photometric error of a dense eld photometry was lowered by 0.05 mag. The endeavor to employ Optical Parametric light Amplication (OPA) to high an- gular resolution astronomical imaging (5) did not succeeded so far but its limitations were demonstrated. Keywords: high angular resolution, imaging, photometry Streszczenie Cele Głównym celem rozprawy doktorskiej było rozwinięcie i przetesto- wanie metod pozyskiwania i redukcji danych w celu zwiększenia dokładności pomiaru fotometrycznego oraz rozdzielczości kąto- wej obrazowania astronomicznego. Metodyka Przedstawiam przegląd opracowanych i zaproponowanych przeze mnie technik precyzyjnych obserwacji astronomicznych. Są to tech- niki: (1) precyzyjnej redukcji wadliwych pixeli (ang. bad pixels), (2) usuwania szumu impulsowego ze zdjęć astronomicznych, (3) pre- cyzyjnej fotometrii oraz obrazowania bardzo słabych źródeł z wy- soką rozdzielczością kątową, (4) efektywnego planowania czasu ekspozycji, oraz (5) superrozdzielczego obrazowania źródeł rozcią- głych. Wyniki Wykazano, że (1) możliwe jest ∼4× precyzyjniejsze usuwanie bad pixels, niż standardowymi metodami. Przegląd metod usuwania szumu impulsowego wykazał (2), że domyślnie używana metoda (Laplacian Edge Detection) jest zwykle najefektywniejsza, ale w nie- których sytuacjach lepiej zastosować metodę Progressive Switching Median (PSM). Zaproponowane przez nas metody bazujące na al- gorytmach ewolucyjnych są w stanie: (3) odzyskać rozkład płasz- czyznowy źródła rozciągłego, które jest jedynie 2-3% jaśniejsze niż tło; oraz (4) znaleźć optymalny podział całkowitego czasu obser- wacji na poszczególne ekspozycje w taki sposób, aby średni dla wszystkich źródeł błąd fotometryczny obniżył się o 0,05 mag. Próba zastosowania wzmacniania parametrycznego światła (OPA) do zwięk- szenia rozdzielczości kątowej obrazowania astronomicznego (5) jak dotąd nie przyniosła pozytywnych rezultatów, ale wykazaliśmy ogra- niczenia stosowania OPA w tym celu. Słowa kluczowe: wysoka rozdzielczość kątowa, obrazowanie, fotome- tria vii This dissertation has been written basing on the scientic results previously reported in the following articles: • A. Popowicz, A. R. Kurek, Z. Filus, Bad pixel modied interpo- lation for astronomical images, 2013PASP..125.1119P • A. Popowicz, A. R. Kurek, A. Pollo, B. Smolka, Beyond the cur- rent noise limit in imaging through turbulent medium, 2015OptL...40.2181P • A. R. Kurek, T. Pięta, Tomasz Stebel, A. Pollo, A. Popowicz, Quantum Telescopes: feasibility and constrains, 2016OptL...41.1094K • A. Popowicz, A. R. Kurek, T. Blachowicz, V. Orlov, B. Smolka, On the eciency of techniques for the reduction of impulsive noise in astronomical images, 2016MNRAS.463.2172P Other results presented in this dissertation are described in the fol- lowing articles which were recently submitted: • A. R. Kurek, A. Stachowski, K. Banaszek, A. Pollo, A. Popowicz, Parametric light amplication in astronomy: a quantum optical model (MNRAS) • A. Popowicz, A. R. Kurek, Optimization of exposure time divi- sion for multiobject photometry (PASP) ix Acknowledgements I would like to express my highest gratitude to my Supervisor, dr hab. Agnieszka Pollo, for enormous help and patience during writing this thesis and thorough supervision over the past 4 years. I also thank for a very friendly atmosphere and numerous useful conversations. xi Contents Abstract iii Streszczeniev Acknowledgements ix 1 Introduction: Angular resolution in astronomical imaging1 1.1 Targets of astronomical imaging..............4 1.1.1 Exoplanets.......................4 1.1.2 Other targets of interest..............5 1.2 Current technological capabilities............. 10 1.3 Fundamental limits...................... 11 1.4 Conclusions........................... 14 1.5 The goals and outline of the thesis............ 14 2 Selected methods of increasing of the angular resolution and photometric precision in astronomical imaging 15 2.1 Bad pixel removal....................... 15 2.1.1 Introduction...................... 15 2.1.1.1 Present methods of bad pixel inter- polation................... 17 2.1.2 Data........................... 18 2.1.3 Test of interpolation methods........... 19 2.1.3.1 Comparison test............. 19 2.1.4 Modied interpolation................ 20 2.1.4.1 Presentation of the idea........ 20 2.1.4.2 Verication................. 24 2.1.5 Conclusions...................... 25 2.2 Impulse noise reduction................... 29 2.2.1 Introduction...................... 29 2.2.1.1 Stationary dark current......... 29 2.2.1.2 Non stationary dark current...... 31 2.2.1.3 Clock induced charge.......... 33 2.2.1.4 Cosmic rays................ 34 2.2.2 Tested methods................... 35 2.2.3 Tests........................... 38 xii 2.2.4 Results......................... 38 2.2.5 Conclusions...................... 42 2.3 Ecient use of telescope time............... 46 2.4 Evolutionary algorithms for image restoration..... 50 2.4.1 Introduction...................... 50 2.4.2 Our method...................... 51 2.4.3 Summary........................ 56 3 Near future 59 3.1 Extremely Large Telescopes................ 59 3.2 Space telescopes....................... 61 3.3 Interferometers, including Event Horizon Telescope. 61 3.4 Hypertelscopes........................ 65 4 Far future 71 4.1 Quantum Telescopes / Optical Parametric Ampli- cation............................... 71 4.1.1 Introduction...................... 71 4.1.2 Classical model.................... 73 4.1.2.1 Simulations................. 73 4.1.2.2 QT: technological feasibility...... 76 4.1.2.3 Conclusions................ 78 4.1.3 Semiclassical model................. 78 4.1.3.1 An updated QT concept........ 79 4.1.3.2 QT – a semiclassical model...... 79 4.1.3.3 Simulations................. 82 4.1.3.4 Results................... 82 4.1.3.5 Conclusions................ 86 4.1.3.6 Discussion................. 86 4.2 Quantum and optimal: SLIVER, SPADE......... 87 4.3 Hypertelescopes in Space................. 87 5 Summary 91 Bibliography 95 xiii List of Abbreviations ATLAST Advanced Technology Large-Aperture Space Telescope CCD Charge Coupled Device CT Classic Telescope DL Diraction Limit EELT European Extremly Large Telescope ELT Extremly Large Telescope EMCCD Electron Multiplying CCD EPE Extrasolar Planets Encyclopedia ESI Earth Similarity Index GA Genetic Algorithm HAR High Angular Resolution HST Hubble Space Telescope IRAF Image Reduction and Analysis Facility JWST James Webb Space Telescope LI Lucky Imaging OPA Optical Parametric Amplication PCB Proxima Centauri B PSNR Peak Signal to Noise Ratio RMS Root Mean Square RMS Random Telegraph Signals SR Strehl Ratio QT Quantum Telescope SNR Signal to Noise Ratio VLBI Very Long Baseline Interferometry 1 Chapter 1 Introduction: Angular resolution in astronomical imaging There is a constant demand to increase the angular resolution in astronomical imaging. It concerns all possible wavelength spans, where the imaging was, is and is about to be performed. The angu- lar resolution of any classical (not based on quantum mechanical tricks) imaging system is limited by its aperture diraction, i.e. so called diraction limit1. Historically, obviously the rst instrument used for astronomi- cal observations was the human eye. Below I list selected features of the human eye as an astronomical instrument. The interested reader is referred to chapter 2 of Wyszecki and Stiles, 2000 for a more detailed information on the human eye properties from as- tronomical point of view, including the light losses, stray light con- tamination, photometric specication etc. • Spectral response of the human eye is wider at the daylight than at night. The optimal sensitivity is at 550 nm, with corre- sponds to the V band in the standard in astronomy Johnson- Cousins UBVRI photometric system (Bessell,