Part I Foundations
1 Astrophysical Information .................................... 3
1.1 Carriers of Information ................................. 4
1.1.1 Electromagnetic Radiation ........................ 4
1.1.2 Matter: From Electrons and Nuclei to
Meteorites ....................................... 5
1.1.3 Neutrinos ........................................ 6
1.1.4 Gravitational Waves .............................. 9
1.1.5 In Situ Observation ............................. 10
1.2 Data Acquisition ....................................... 12
1.2.1 The Main Characteristics of Photons ............. 12
1.2.2 Observing Systems ............................... 12
1.2.3 Reaching a Systematic Description of
Observation ..................................... 27
1.3 Global Organisation of Astronomy ....................... 28
1.3.1 People .......................................... 29
1.3.2 Research Policies and Institutions .............. 31
1.3.3 Publications .................................... 34
2 The Earth Atmosphere and Space .............................. 39
2.1 Physical and Chemical Structure of the Atmosphere ...... 40
2.1.1 Vertical Structure .............................. 40
2.1.2 Constituents of the Atmosphere .................. 41
2.2 Absorption of Radiation ................................ 45
2.3 Atmospheric Emission ................................... 50
2.3.1 Fluorescent Emission ............................ 50
2.3.2 Thermal Emission ................................ 55
2.3.3 Differential Measurement Techniques ............. 56
2.4 Scattering of Radiation ................................ 58
2.5 Atmospheric Refraction and Dispersion .................. 61
2.4 2.6 Turbulence Structure of the Earth Atmosphere ...... 62
2.6.1 Turbulence in the Lower and Middle Atmosphere ... 63
2.6.2 Ionospheric Turbulence .......................... 70
2.7 The Atmosphere as Radiation Converter .................. 70
2.7.1 Ground-Based Gamma-Ray Astronomy ................ 70
2.7.2 Air Showers and Cosmic Rays ..................... 71
2.8 Terrestrial Observing Sites ............................ 71
2.8.1 Visible, Infrared, and Millimetre
Observations .................................... 72
2.8.2 Centimetre and Metre Wave Radioastronomy ........ 74
2.8.3 Very High Energy Gamma-Ray Astronomy ............ 75
2.8.4 Very High Energy Cosmic Radiation ............... 75
2.8.5 Man-Made Pollution and Interference ............. 75
2.8.6 The Antarctic ................................... 76
2.9 Observation from Space ................................. 77
2.9.1 The Advantages of Observation from Space ........ 79
2.9.2 Sources of Perturbation ......................... 79
2.9.3 Choice of Orbits ................................ 86
2.10 The Moon as an Astronomical Site ....................... 87
Problems .................................................... 89
3 Radiation and Photometry .................................... 93
3.1 Radiometry ............................................. 94
3.2 Aspects of Radiation ................................... 99
3.2.1 Blackbody Radiation ............................. 99
3.2.2 Coherence ...................................... 100
3.3 Magnitudes ............................................ 104
3.4 Photometry Through the Atmosphere ..................... 109
3.5 Calibration and Intensity Standards ................... 110
3.5.1 Radiofrequencies ............................... 110
3.5.2 Submillimetre, Infrared, and Visible ........... 112
3.5.3 Ultraviolet and X Rays ......................... 117
3.5.4 Gamma-Ray Radiation ............................ 120
3.5.5 Some Examples of Spectrophotometry ............. 120
3.6 Calibration of Angular Dimensions ..................... 123
Problems ................................................... 124
4 Space-Time Reference Frames ................................ 127
4.1 Spatial Reference Systems ............................. 129
4.1.1 Definitions of Spatial Frames .................. 129
4.1.2 Astronomical Reference Frames .................. 131
4.1.3 Change of Frame ................................ 138
4.2 Practical Realisation of Spatial Frames ............... 144
4.2.1 Celestial Reference Systems .................... 144
4.2.2 Fundamental Catalogues ......................... 145
4.2.3 The Extragalactic System ....................... 147
4.2.4 The Hipparcos Frame ............................ 151
4.2.5 The Near Future: The Gaia Mission .............. 155
4.3 Temporal Reference Systems ............................ 157
4.3.1 Time Scales .................................... 157
4.3.2 Atomic Time .................................... 161
4.3.3 Coordinated Universal Time (CUT or UTC) ........ 164
4.3.4 GPS Time ....................................... 166
4.3.5 Dynamical Time Scales .......................... 167
4.3.6 Dates and Epochs. Dealing with Long Periods .... 169
Part II Data Collection
5 Telescopes and Images ...................................... 175
5.1 Image and Object in Astronomy ......................... 176
5.1.1 The Telescope and Geometrical Optics ........... 177
5.1.2 Gravitational Optics ........................... 183
5.2 Telescopes ............................................ I84
5.2.1 Radiotelescopes ................................ 185
5.2.2 Ground-Based Optical Telescopes: Visible and
Near Infrared .................................. 189
5.2.3 Space Telescopes, from Ultraviolet to
Submillimetre .................................. 194
5.2.4 X-Ray Telescopes ............................... 199
5.2.5 Gamma-Ray Telescopes ........................... 201
6 Diffraction and Image Formation ............................ 209
6.1 Diffraction by an Arbitrary Aperture .................. 210
6.1.1 The Zernike Theorem ............................ 211
6.1.2 Coherence Etendue .............................. 214
6.1.3 Diffraction at Infinity ........................ 216
6.1.4 Spatial Filtering by a Pupil ................... 221
6.2 The Earth Atmosphere and Coherence Losses ............. 228
6.2.1 Perturbations of the Wavefront ................. 229
6.2.2 The Perturbed Image ............................ 232
6.2.3 Effect of the Atmosphere on Interferometry ..... 238
6.3 Adaptive Optics ....................................... 240
6.3.1 Wavefront Measurement .......................... 241
6.3.2 Phase Correction Devices ....................... 245
6.3.3 The Final Image ................................ 246
6.3.4 Sensitivity and Reference Sources .............. 248
6.3.5 New Concepts ................................... 252
6.4 Astronomical Interferometry ........................... 256
6.4.1 Obtaining an Interferometer Signal ............. 257
6.4.2 Light Transfer ................................. 262
6.4.3 Temporal Coherence ............................. 264
6.4.4 Loss of Spatial Coherence ...................... 264
6.4.5 Calibrating the Instrumental MTF ............... 268
6.4.6 Phase Closure .................................. 271
6.5 Astronomical Interferometers .......................... 274
6.5.1 Radiotelescope Arrays .......................... 274
6.5.2 Ground-Based Optical Arrays .................... 286
6.5.3 Space-Based Optical Interferometry ............. 294
6.6 High Dynamic Range Imaging (HDRI) ..................... 298
6.6.1 Coronagraphy and Apodisation ................... 299
6.6.2 Nulling Interferometry ......................... 311
Problems ................................................... 316
7 Detectors .................................................. 323
7.1 General Properties .................................... 324
7.1.1 Amplitude Detectors. Quadratic Detectors ....... 325
7.1.2 Spatial Structure of Detectors ................. 326
7.1.3 Temporal Response .............................. 329
7.1.4 Noise .......................................... 330
7.1.5 Characterisation of Detectors .................. 331
7.2 Fundamental Fluctuations .............................. 332
7.2.1 Quantum Noise .................................. 336
7.2.2 Thermal Noise .................................. 340
7.3 Physical Principles of the Detection of
Electromagnetic Radiation ............................. 343
7.3.1 Detection of Quanta ............................ 344
7.3.2 Detection of the Electromagnetic Field ......... 355
7.4 Astronomical Detectors from X Ray to Submillimetre .... 355
7.4.1 Noise Performance .............................. 356
7.4.2 Photographic Plates ............................ 357
7.4.3 Photomultipliers and Classical Cameras:
X Ray, UV, and Visible ......................... 359
7.4.4 X-Ray Detection (0.1-10 keV) ................... 364
7.4.5 Solid-State Imagers ............................ 365
7.4.6 Charge Coupled Device (CCD) .................... 366
7.4.7 The Hybrid CMOS Detector ....................... 373
7.4.8 Observing Conditions in the Infrared ........... 380
7.4.9 Development of Solid-State Imaging Arrays ...... 381
7.4.10 Bolometers ..................................... 383
7.5 Astronomical Detectors: Radiofrequencies .............. 387
7.5.1 General Features ............................... 388
7.5.2 Heterodyne Detection ........................... 393
7.5.3 The Diversity of Radioastronomy ................ 403
7.6 Observing Systems for Gamma-Ray Astronomy ............. 404
7.6.1 Spatial Resolution of Gamma-Ray Sources ........ 407
7.6.2 Spectral Analysis of Gamma-Ray Sources ......... 412
7.7 Neutrino Observing Systems ............................ 420
7.7.1 Radiochemical Detection of Solar Neutrinos ..... 421
7.7.2 Neutrino Detection by Cherenkov Radiation ...... 424
7.7.3 High Energy Neutrino Astronomy ................. 425
7.8 Gravitational Wave Detection .......................... 431
Problems ................................................... 437
8 Spectral Analysis .......................................... 441
8.1 Astrophysical Spectra ................................. 442
8.1.1 Formation of Spectra ........................... 442
8.1.2 Information in Spectrometry .................... 448
8.2 Spectrometers and Their Properties .................... 455
8.2.1 Quantities Characterising a Spectrometer ....... 456
8.2.2 Spectral Discrimination ........................ 459
8.2.3 The Modes of a Spectrometer .................... 460
8.3 Interferometric Spectrometers ......................... 462
8.3.1 General Criteria ............................... 462
8.3.2 Interference Filters ........................... 463
8.3.3 Grating Spectrometers .......................... 463
8.3.4 Fourier Transform Spectrometer ................. 481
8.3.5 The Fabry-Perot Spectrometer ................... 489
8.3.6 The Bragg Crystal Spectrometer (X-Ray
Region) ........................................ 491
8.4 Radiofrequency Spectrometry ........................... 494
8.4.1 Spectral Discrimination Methods ................ 495
8.4.2 Submillimetre Spectroscopy ..................... 501
8.5 Resonance Spectrometers ............................... 503
Problems ................................................... 504
Part III Data Analysis
9 The Signal in Astronomy .................................... 509
9.1 The Signal and Its Fluctuations ....................... 510
9.1.1 Observing System and Signal .................... 510
9.1.2 Signal and Fluctuations. Noise ................. 511
9.1.3 Elementary Signal Processing ................... 519
9.1.4 A Specific Example of Data Processing .......... 528
9.2 Complete Model of an Observing System ................. 529
9.3 Overall Performance of an Observing System ............ 532
9.3.1 Observing with the IRAM Millimetre
Interferometer ................................. 533
9.3.2 Observing with NAOS Adaptive Optics ............ 536
9.3.3 Observing with the Photometric Satellite
COROT .......................................... 538
9.3.4 Observing with a Coded Mask Gamma-Ray
Instrument ..................................... 541
9.4 Removing Instrumental Signatures ...................... 544
9.4.1 Intrinsic Emission from the Instrument ......... 545
9.4.2 Dark Current ................................... 545
9.4.1 Non-Linearity Defects .......................... 546
9.4.4 Bias ........................................... 547
9.4.5 Light Interference ............................. 547
9.4.6 Flat Field Corrections ......................... 548
9.4.7 Defective Pixels ............................... 549
9.4.8 Effects of High Energy Particle Impacts ........ 549
9.5 The Problem of Estimation ............................. 550
9.5.1 Samples and Statistics ......................... 550
9.5.2 Point Estimation ............................... 551
9.5.3 Elements of Decision Theory .................... 551
9.5.4 Properties of Estimators ....................... 554
9.5.5 Fréchet or Rao-Cramér Inequality ............... 564
9.5.6 Efficient Estimators ........................... 566
9.5.7 Efficiency of an Estimator ..................... 568
9.5.8 Biased Estimators .............................. 568
9.5.9 Minimum Variance Bound and Fisher
Information .................................... 570
9.5.10 Multidimensional Case .......................... 570
9.5.11 Robust Estimators .............................. 571
9.5.12 Some Classic Methods ........................... 573
9.6 From Data to Object: the Inverse Problem .............. 575
9.6.1 Posing the Problem ............................. 576
9.6.2 Well-Posed Problems ............................ 579
9.6.3 Conventional Inversion Methods ................. 581
9.6.4 Inversion Methods with Regularisation .......... 587
9.6.5 Application to Adaptive Optics Imaging ......... 592
9.6.6 Application to Nulling Interferometry .......... 595
Problems ................................................... 597
10 Sky Surveys and Virtual Observatories ...................... 605
10.1 Statistical Astrophysics .............................. 605
10.2 Large Sky Surveys ..................................... 608
10.2.1 Sky Surveys at Visible Wavelengths ............. 610
10.2.2 Infrared Sky Surveys ........................... 614
10.3 A Virtual Observatory ................................. 615
A Fourier Transforms ......................................... 619
A.l Definitions and Properties ............................ 619
A.1.1 Definitions .................................... 619
A.1.2 Some Properties ................................ 620
A.1.3 Important Special Cases in One Dimension ....... 622
A.1.4 Important Special Cases in Two Dimensions ...... 625
A.1.5 Important Theorems ............................. 626
A.2 Physical Quantities and Fourier Transforms ............ 631
A.3 Wavelets .............................................. 635
В Random Processes and Variables ............................. 637
B.l Random Variables ...................................... 637
B.2 Random or Stochastic Processes ........................ 644
B.3 Physical Measurements and Estimates ................... 653
B.3.1 An Example of Estimation: The Law of Large
Numbers ........................................ 654
B.3.2 Estimating the Moments of a Process ............ 655
С Physical and Astronomical Constants ........................ 659
D Tables of Space Missions ................................... 661
E Webography ................................................. 663
E.l Main Earth-Based Telescopes ........................... 663
E.2 Recent Space Missions ................................. 667
E.3 Databases ............................................. 669
E.4 Journals .............................................. 672
E.5 Bibliographical Research .............................. 673
E.6 Image Sources ......................................... 673
E.7 Education ............................................. 675
E.8 Computing and Astronomy ............................... 676
E.9 Resources ............................................. 677
F Acronyms ................................................... 679
Bibliography ............................................... 687
Index ......................................................... 705
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