The detonation of the Klaxosaur Bomb causes an explosion seen all the way back on Earth. Strelizia True Apus is noted to be so far from Earth that there are no recognisable stars, and the sky and perspective is completely different (there are also noticably more stars in the sky than in space in the Solar System).
We can see at least 6 Spiral galaxies, excluding the Milky Way (the first galaxy is a bit hard to see as it's only visible in the fade in, but you can definately see it there).
= 2*atan(314/(1614/tan(70/2)))
= 0.18383961 rad
= 10.533233760357172 degrees
Enter that through the angscaler, and we can determine that the Milky Way is at least 5131600000000000000000m away. The full shot is even further away, but for now let's leave it at that. The light is clearly visible in the middle of the day and from across the Universe, which would mean if'd have to be at least comparable to the luminousity of the Sun. The apparent magnitude of the Sun is -26.74.
-26.74 = -26.73 - 2.5log((L/3.846*10^26)(146000000000/(5131600000000000000000))^2)
(146000000000/(5131600000000000000000))^2) = 8.09468809e-22
-26.74 - -26.73 = 8.09468809e-22/((L/3.846*10^26)
-0.01 = -2.5Log(8.09468809e-22/((L/3.846*10^26))
-0.01/-2.5 = (8.09468809e-22/((L/3.846*10^26))
10^(0.004) = (8.09468809e-22/((L/3.846*10^26))
1.00925289 = (8.09468809e-22/((L/3.846*10^26))
1.00925289 X (3.864*10e26) = 9.46317256e-10
3.89975317e27/8.09468809e-22 = 4.81766947e48 joules
The light lasts 3 days.
= 259200s
E = 4.81766947e48 X 259200
= 1.24873993e54/10^44
= 12.487399300 GIGAFOE
Final Results
Klaxosaur Bomb = >12.487 GIGAFOE