scan_mode

[alle-ira]

Sect 4.5 -
From the IVOA perspective of keeping separate time, space and energy domains, should we adopt two parameters: one for scanning in spatial coordinates (for instance sky_scan_mode) and the other for frequency scanning (for instance freq_scan_mode)?

[Bonnarel]

Can we imagine some vocabulary rule which allows combination of two terms ? So that we may use the same FIELD for either axis scan exclusively or combination of both ? This to avoid too much empty FIELDS in case.

[alle-ira]

We agree on the proposal of keeping one parameter, accompanied by a vocabulary and its rules. We could imagine scan_mode as composed by two terms, the first one (always present) defining the sky scanning mode and the second (optional) describing the frequency scanning mode if present. As an example, a frequency switching observation could have scan_mode='on, freq_switch' while an on-the-fly map could have scan_mode='otf_map' only.