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ALMA Calibration Introduction

Learn about the process of calibration in ALMA observations, including measurement and adjustment of instrumental parameters. Explore various calibration types such as amplitude, phase, bandpass, polarization, and more. Join the discussion on different calibration techniques and advancements in the field.

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ALMA Calibration Introduction

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  1. ALMA CalibrationIntroduction Bryan Butler NRAO

  2. Definition calibration: 1: the act or process of calibrating : the state of being calibrated calibrate: 4: to measure or adjust precisely so, in the broadest sense, “calibration” includes the effort of measurement (and application) of all instrumental parameters. split into two types: 1 – quantities which must be known when the observation is made (signal adjustments pre-correlation) – these are mostly component values which change only infrequently, or array parameters which change with antenna moves, e.g.; 2 – quantities which can be applied to the data at a later date (but might have to be measured during obsn) – these are mostly instrumental parameters which change with time or ambient conditions. the timescale is important!

  3. The Elements • Antenna • Pointing • Surface & primary beam • subreflector & feed positioning • Amplitude • Fluctuating (opacity, receiver – Tsys; decorrelation) • Flux density scale • Single dish • Delay • Geometric • Atmosphere (the fluctuating part is what we often call “phase”) • Antenna structure • Electronics • Bandpass • Polarization • Miscellaneous (solar, e.g.)

  4. Agenda Amplitude Calibration 13:50 Introduction Guilloteau 14:00 Tests of Dual-Load System Welch 14:10 Tests of S/T-Vane System Pintado 14:20 New Grid System Guilloteau, Lamb 14:40 New Absolute Scheme Welch 15:00 Mod to New Absolute Scheme Guilloteau 15:10 Receiver Gain Stability D’Addario, Guilloteau 15:20 Discussion 15:30 Break Phase Calibration 15:40 Introduction Wootten 15:50 Fast Switching Holdaway 16:00 Discussion

  5. Agenda Bandpass Calibration 16:10 Introduction Guilloteau 16:20 Use of Astronomical Sources Guilloteau 16:40 Discussion Polarization Calibration 16:50 Introduction Butler 17:00 Discussion 17:10 Miscellaneous (Antenna Location, Focus, Delay, etc...) Butler ACA 17:30 Introduction Hasegawa 17:35 Discussion 17:40 Milestones Guilloteau, Wootten, Butler

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