Transit of the Galactic Plane
An interesting drift scan is the measurement of hydrogen emissions from our own Milky Way. We aim the dish at a fixed point in which the Milky Way passes twice within 24 hours. This is also clearly visible in the drift scan below. The color plot was created with a simple Python script. The black and white plot is a conversion of the data with Excel into color values (Conditional Format).
The sinusoidal structure is related to the Doppler effect. The Doppler shift is mainly due to the movement of the earth around the sun (30 km/s) and due to the rotation of the earth. We always look in different directions during the day with respect to this direction of movement.
The vertical axis is Time (total 24 hours).
Here a small movie from the Milky Way transit: https://youtu.be/aJnVMv_7o-k