Assertion: telescope's mirror | /r/HasProperty | 75.76 m2
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Source sentences:
text: However, all of the light collected by the Keck Observatory primary mirrors (75.76 m2) is sent to the secondary mirror and the instruments, compared to GTC's primary mirror, which has an effective light-collection area of 73.4 m2, or 2.36 m2 (25.4 sq ft) less than each of the Keck Observatory primary mirrors.