Galactic structure and nearby galaxies

Brief description

Use data from the Leiden/Dwingeloo radio survey of neutral hydrogen in the Galaxy to determine the spiral arm structure of the Milky Way. By assuming that Galactic material moves in circular orbits at angular speeds that depend only their orbital radius (distance to the Galactic Centre), you can interpret redshifts in any directions as a distance along the line of sight. Peculiar motions within the Galaxy can also be determined.

Several nearby galaxies were seen for the first time in these data, previously hidden behind the dust of the Galactic plane. See if you can spot them (hint: tey will appear as material with an anomalous velocity).