Forty Seven

That special Star Trek number. Let's list the known occurrences, shall we?

There's not many. Most of the time the writers seemed to be desperately trying to avoid using it.

Terra Nova  3 hours 17 minutes journey time - 3+1=
Fortunate Son Travis suggests bypassing circuit L-47 to get the long range sensors back online.
Desert Crossing The sensor grid gap opens every 46 minutes for less than one minute. 46+1=47
Night In Sickbay The episode opens at 8:47 pm.
Judgment The asteroid fragment is at 2+2 (4) 7 mark 4
Bounty The hydrothermal pools are 227km etc (2+2=4, 7. A desperate reach) 
Impulse According to T'Pol, the Seleya's crew complement was 147.
Similitude Sim's torpedo case coffin is number 2744506
Stratagem 7 Red giants in 40 light years
Cold Station 12 Soong initiates  Protocol 047
Kir'Shara The maintenance log Reed shows Trip has lots of 47's in it. 
United Enterprise will intercept the Romulan Drone ship in 47 minutes.
Affliction Satellite grid 137 (1+3=4) was offline when Phlox was kidnapped. 
Hadron count at the Rigelian ship is 147.
Divergence There are 47 minutes until the warp reactor breaches.
In A Mirror, Darkly 2 There are 47 Alternate Universe crew on Defiant.
Demons The Terra Prime meeting is held at junction 4, level 7.
Terra Prime The Medical Unit is labeled 03-47.
These Are The Voyages... Takes place on stardate 47457.1. 

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