In this short course I will present and discuss the observational properties and some theoretical implications of astrophysical jets (in particular AGN jets) as revealed by their polarised emission, throughout the EM spectrum. The course will start with a brief discussion of the observational techniques and how to interpret the polarisation information, and will proceed with a review of the current status of our knowledge regarding a polarimetric view of jets. I will focus on the discussion of some key physical parameters and measurements that can be extracted from the polarimetric data, and the physical insights they provide. Finally, I will discuss some theoretical aspects which can be tested or probed with polarimetric measurements. To conclude, I will give some personal views (criticisms and proposals) on the use of polarimetric data in combination with multi-band light-curves and SEDs to probe the physics of AGNs, and specially blazars.
The Earth’s atmosphere is the medium through which electromagnetic
signals emitted by or received by ground-based or space-based human-
made devices travel. The molecular and aerosol composition alter the
transmission properties in a peculiar wavelength-dependent way. Several
instruments allow to monitor the integral or the height-resolved
transparency of the atmosphere, the scattering and absorption
properties of the suspended particles, at different wavelengths and with
different characteristics in terms of exposure (day/night), acceptance,
resolution, etc. This course will cover the theoretical background
needed for discussing instruments and methods for atmospheric measurements. The goal is to familiarise students with these active fields of research, which count with a great variety of applications, among which for the assessment of the Earth's greenhouse effect and hence its climate change.