One More Optically Thin Imaging Example

• Supernova 1987A: ALMA images of dust and CO molecules
• the power of spectroscopy: line-based 3D imaging

The Planck Spectrum

• most awesomest example plotted
• basic properties
• Wein's displacement laws
• brightness/antenna temperature, e.g., as measured by Penzias & Wilson, and modern result (Mather+ 1994)

Thermal Radiation: Kirchhoff's Law

• thermal vs blackbody emitters
• example: Cas A X-ray spectrum