Assertion: telescope's mirror | /r/HasProperty | m1
Facets:
Source sentences:
text: The Rubin Observatory primary mirror (M1) is 8.4 meters (28 ft) in diameter, the secondary mirror (M2) is 3.4 meters (11.2 ft) in diameter, and the tertiary mirror (M3), inside the ring-like primary, is 5.0 meters (16 ft) in diameter.