# CLASS internal data format

Observations with a single dish telescope may be divided in two categories:

1. Pointed observation: The telescope beam is pointed toward a fixed position of the source during the signal integration. In its simplest form, the scan is composed of a spectrum whose intensity is accumulated during the scan duration. Nothing prevents more complex scan definitions, e.g. a scan composed of several shorter integrations, all at the same position on the sky.
2. On-The-Fly (OTF) observation: The telescope beam continuously drifts on source during the integration to make a map of the source. The scan is then composed of set of spectra regularly dumped (typically every 1 second) during a contiguous portion of time (typically 10 minutes). Each dumped spectra corresponds to a different position on the sky.

Subsections

- Pointed observation
- On–The–Fly observation