Assertion: reflecting telescope's mirror | /r/HasProperty | removed
Facets:
value: anyway
type: MANNER
value: frequently
type: TEMPORAL
Source sentences:
text: This meant they need more than one mirror per telescope since mirrors had to be frequently removed and re-polished.
text: The second mirror was left in place in the telescope when it was dismantled, but was removed when the tube was crushed.
text: Some people prefer to remove the primary mirror completely from the telescope when aligning the secondary mirror, especially if the primary mirror needs to be removed anyway to be center-marked.