Interstellar Dust

• Barnard 68: optical
• Barnard 68: into the infrared

Eating Your Peas: Coordinate Systems

• Equatorial coordinates: RA and dec
• Galactic coordinates: (l,b) and cylindrical
• latitude and logitude map: sky view
• Why Galactic coords? star density maps juxtaposed
• converting from equatorial to Galactic: a handy-dandy online calculator

Mapping the Milky Way

• Diffuse components: gas and dust
  • neutral atomic hydrogen (H I): 21-cm hyperfine emission
  • molecular hydrogen (really: CO molecules)
  • ionized hydrogen (really: H-alpha recombinations; northern sky from WHAM, southern sky from SHASSA, all-sky)
  • all hydrogen (really: high-energy gamma-rays)
  • warm dust (as seen in the far infrared)