(portion of the celestial sphere where a survey's observations aim)
The phrase survey field (or survey region or sometimes field of view
or FOV)
is used for the portion of the celestial sphere where an
astronomical survey's observations are carried out.
The phrase all sky survey means just that,
but is also used to indicate a substantial fraction of the sky,
e.g., for survey performed from a single ground location,
all that is reachable.
Surveys often reuse a past survey field to carry out
additional observations, e.g., covering other parts of the
electromagnetic spectrum,
greater depth, or adding spectrography.
A deep field is a (generally small) field used for
extreme depth, i.e., looking for distant and therefore faint
objects.
The term wide field is sometimes used for a large survey field,
but also is used to indicate a large field of view.
Survey fields are often re-used, i.e., a subsequent survey
is intended to gather more data on the field's known objects (and
to search for more), and for the same reasons, sometimes a new
survey field is specifically chosen to overlap with an existing
field. These are especially true of deep fields.