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1. Radio Antennas
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Participants to IMISS1 and
Contents
In Memoriam
Preface
Participants to IMISS1 and IMISS2
1. Radio Antennas
1.1 Introduction
1.2 Basic Principles
1.3 The perfect Single-Dish antenna
1.4 The real Single-Dish Antenna
1.4.1 Systematic Deformations: Defocus, Coma, Astigmatism
1.4.2 Random Errors
1.5 Radiometric Relations
2. Millimetre Interferometers
2.1 Basic principle
2.2 The Heterodyne Interferometer
2.2.1 Source Size Effects
2.2.2 Finite Bandwidth
2.3 Delay Tracking and Frequency Conversion
2.4 Fringe Stopping and Complex Correlator
2.5 Fourier Transform and Related Approximations
2.6 Array Geometry & Baseline Measurements
3. Millimetre Very Long Baseline Interferometry
3.1 Introduction
3.2 mm-VLBI Arrays
3.2.1 The CMVA Array
3.2.2 The VLBA Array
3.3 Available Resolution
3.4 Polarization Observations
3.5 The Feasibility of mm-VLBI: Signal-to-Noise Ratio and Detections
3.6 From observations to correlations, step by step
3.6.1 Observing Techniques
3.6.2 Data Recording
3.6.3 Correlation Time
3.6.4 Phase Correction
3.6.5 Correlation
3.7 The observable sources with mm-VLBI
3.7.1 Which Kind of sources can we observe
3.7.2 The field of view
3.7.3 An example: mm-VLBI Observations of QSO 3C273
4. Introduction to Optical/Near-Infrared Interferometry
4.1 Introduction
4.1.1 Brief history of optical interferometry
4.1.2 Current and future optical interferometers
4.2 Optical versus millimeter radio interferometry
4.2.1 Common issues
4.2.2 Main differences
4.3 Description of optical interferometers
4.3.1 Functional description
4.3.2 Specific applications
4.4 Formation of the interferometric fringes
4.4.1 Beam combination
4.4.2 Fringe coding and detection
4.5 Main challenges in interferometry
4.5.1 Atmosphere turbulence
4.5.2 Other atmosphere systematics
4.5.3 Fighting the atmosphere: complexity and accuracy
4.5.4 Noise sources - Sensitivity
4.6 Conclusion
Figure credits
Internet resources
5. Receivers : an overview for non-specialists
5.1 Introduction
5.2 Coupling optics
5.3 Why we need heterodyne receivers
5.4 Local oscillator system
5.5 Local oscillator injection
5.6 Photon-assisted tunneling
5.7 Mixer
5.8 Cryostat
5.9 Actual receivers
6. Cross Correlators
6.1 Introduction
6.2 Basic Theory
6.3 The Correlator in Practice
6.3.1 Digitization of the input signal and clipping correction
6.3.2 Time lag windows and spectral resolution
6.3.3 Main limitations
6.4 The correlator on Plateau de Bure
6.4.1 The third-generation correlator
6.5 Appendix
6.5.1 Summary of definitions
6.5.2 Clipping correction for 4-level quantization
7. LO System and Signal Transport
7.1 An Heterodyne Interferometer
7.1.1 The simple interferometer
7.1.2 The heterodyne interferometer
7.1.3 Frequency conversion
7.1.4 Signal phase
7.2 Delay lines requirements
7.2.1 Single sideband processing in a finite bandwidth
7.2.2 Double sideband system
7.3 sideband separation
7.3.1 Fringe rate method
7.3.2 Phase switching method
7.4 The PdB Signal and LO transport system
7.4.1 Signal path
7.4.2 LO generation
7.4.3 Further signal processing
7.4.4 Phase stability requirements
7.4.5 Cable electrical length control
7.5 Next generation instruments
8. The Plateau de Bure Interferometer
8.1 History
8.2 Description
8.3 Array operation
8.3.1 Array calibration
8.3.2 Array observations
8.4 Proposal submission and contact people
9. Bandpass and Phase Calibration
9.1 Definitions and formalism
9.1.1 Baseline based vs antenna based gains
9.1.2 Gain corrections
9.2 Bandpass calibration
9.2.1 Bandpass measurement
9.2.2 IF passband calibration
9.2.3 RF bandpass calibration
9.2.4 Sideband calibration
9.3 Phase calibration
9.3.1 Phase referencing by a nearby point source
9.3.2 Phase referencing by a point source in the primary beam
9.3.3 Phase referencing using another band or another frequency
10. Atmospheric Absorption
10.1 The physical and chemical structure of the Atmosphere
10.1.1 Constituents of the atmosphere
10.1.2 Thermodynamics of the air
10.1.3 Hydrostatic equilibrium
10.1.4 Water
10.2 Atmospheric radiative transfer in the mm/submm
10.2.1 Introduction
10.2.2 Unpolarized radiative transfer equation
10.2.3 Spectroscopic parameters
10.2.4 Line shapes
10.2.5 Non-resonant absorption
10.2.6 Radiative transfer through atmospheric hydrometeors
10.3 Fourier Transform Spectroscopy for site testing
10.3.1 FTS measurements at Mauna Kea
10.3.2 FTS measurements at Atacama (future ALMA site)
10.4 Atmospheric absorption evaluation
10.4.1 Correction for atmospheric absorption,
10.5 Phase fluctuation evaluation
10.5.1 Cause of Phase Fluctuations
10.5.2 Simulations of phase fluctuations
10.5.3 Phase Correction Methods
10.5.4 Example of phase correction
11. Atmospheric Fluctuations
11.1 Introduction
11.2 Hydrodynamical basics of turbulent motion
11.3 Statistical properties of turbulence
11.4 Remote sounding techniques
11.5 Current phase correction at IRAM
11.6 Phase correction during off-line data reduction
11.7 Frequently asked questions
12. Amplitude and Flux Calibration
12.1 Definition and Formalism
12.2 Single-dish Calibration of the Amplitude
12.2.1 Low opacity approximation and implication for
12.2.2 Absolute errors on
due to instrumental parameters
12.2.3 Relative errors or errors on
12.2.4 Estimate of the thermal noise
12.3 Flux Calibration (visitor's nightmare)
12.3.1 Introduction
12.3.2 Calibration procedure at Bure
12.3.3 Determining the absolute flux scale on a project
12.3.4 Possible biases and remedies
12.3.5 The program FLUX
12.4 Interferometric Calibration of the Amplitude
12.4.1 Correction for the antenna gain
12.4.2 Estimate of the atmospheric decorrelation factor
12.4.3 Fitting Splines: the last step
12.4.4 A few final checks
13. Calibration of data in Practice
13.1 Introduction
13.1.1 Contents of the account
13.1.2 Before starting the data reduction
13.1.3 Activating the CLIC environment
13.2 The ``First Look'' procedure
13.3 The ``Standard Calibration (2-receivers)'' procedure
13.3.1 Inputs
13.3.2 Actions or Outputs
13.3.3 Results of the calibration
14.
Plane Analysis
14.1
tables
14.1.1
table contents
14.1.2 How to create a
Table
14.2
data plots
14.3 Data editing
14.4 Position shift
14.5 Averaging
14.5.1 Data compression
14.5.2 Circular averaging
14.6 Model fitting
14.6.1 Position measurement
14.7 Continuum source subtraction
14.8 Self calibration by a point source
15. The Imaging Principles
15.1 Fourier Transform
15.1.1 Direct Fourier Transform
15.1.2 Fast Fourier Transform
15.1.3 Gridding Process
15.2 Sampling & Aliasing
15.3 Convolution and Aliasing
15.4 Error Analysis
15.5 Weighing and Tapering
15.6 The GILDAS implementation
15.7 Deconvolution
15.7.1 The CLEAN method
15.7.2 Interpretation of CLEAN
15.7.3 The CLEAN variants
15.7.4 The GILDAS implementation
16. Advanced Imaging Methods: WIPE
16.1 Introduction
16.2 Object space
16.3 Experimental data space
16.4 Image reconstruction process
16.4.1 Synthesized aperture
16.4.2 Synthetic beam
16.4.3 Regularization frequency list
16.4.4 Data space
16.4.5 Object representation space
16.4.6 Objective functional
16.4.7 Uniqueness and robustness
16.5 Implementation of WIPE at IRAM
Glossary
17. Mosaicing
17.1 Introduction
17.2 Image formation in a mosaic
17.3 Mosaicing in practice
17.4 A CLEAN-based algorithm for mosaic deconvolution
17.5 Artifacts and instrumental effects
17.6 Concluding remarks
18. Imaging in Practice
18.1 Visualisation
18.2 Photometry
18.2.1 From Flux density to Brightness temperature
18.2.2 Accuracy of Flux density estimates
18.3 Short Spacings
18.3.1 UV_SINGLE
18.4 Dirty Tricks
18.4.1 MOMENTS
18.4.2 Continuum Subtraction
19. Low Signal-to-noise Analysis
19.1 Continuum Source
19.1.1 Flux measurement
19.1.2 Other parameters
19.2 Spectral Line Sources
20. Basic Principles of Radio Astrometry
20.1 Introduction and Basic Formalism
20.2 The Phase Equation
20.3 Determination of Source Coordinates and Errors
20.4 Accurate Position Measurements with the IRAM Interferometer
20.4.1 Absolute positions
20.4.2 Relative Positions and Self-calibration Techniques
20.5 Sources of Position Uncertainty
20.5.1 Known Limitations
20.5.2 Practical Details
21. Mm versus Optical Interferometry: a qualitative comparison
21.1 The basic equation of interferometry
21.1.1 Additive interferometry
21.1.2 Multiplicative interferometry
21.2 Getting the fringes
21.3 Atmospheric behaviour and noise properties
Bibliography
Anne Dutrey