Halcyon could think anything he likes... but Blair saw it, and I believe I mentioned his description below.
And LOAF, that's the whole point - only one source gives a number, and it's all too easy to accidentally skip a "0". Admittedly, the fact that they also list its mass as 1,720 tonnes makes it less likely that it was an error - but come on, the weapon mounted on the Sivar is supposedly so large that it forms the keel of the Confederation class. But if it had been small enough to mount on a 103 metre ship..