I would guess the reclosure (aka trigger) voltage is around 180..240V peak (the rme does not matter, mainly with non-sinusoidal shapes).
200V ballast OCV means about 280V peak, sufficiently (you always need some margin) above the 240V upper limit guess I made.
But a 105Varc lamp does mean 105V arc voltage, but on top of that are "reignition spikes" - voltage overshoots each time the current passes zero and so the arc extinguishes and has to reignite again for the next half cycle. These peaks tend to be few 10's of V (example here
), so I would guess below 150V for a nominally 105V arc lamp.
And these reignition spikes then should not trigger the starter, so the starter trigger voltage has to be then above the 150V, therefore (some margin again) the 180V as my minimum limit guess.
And as any other device, the starter triggering voltage will exhibit some tolerance, I would expect about +/-10..15% to be about the ball park, so there is not much room out of the guesses I made...