My worst Catasetum killer
 

Symptoms develloped very fast within 2-3 days.
When watering a few days ago the plant looked healthy and strong, forming a good flower spike. Then there were low temps outside, autumn fog blocked the sun, and for astronomical reasons the daylength rapidly decreases after equinox.. In consequence the ventilation was shut down, and eventually the plant stood a bit tight.
Luckily so far the only plant out of a large number. I separated it immediately. After four more days even all backbulbs turn soft and rotten.
My diagnosis is soft rot, probably Erwinia, but not tested in a laboratory so far. Not a pretty sight. Continuous monitoring is the order of the day.

Ohh, so sorry to hear about your orchid, this one really looks bad:-( I hope it will make it maybe somehow?

Oh dear. :( It did decline quickly. Hopefully that was the only casualty though.

how low did the temps get and were they prolonged lows ? I have heard that low temps are the ultimate killer of cats.

It is more a sudden lack of light or moving air or a combination rather than low temps alone. Temperature was not lower than 15°C. What makes me wonder is that only one out of 300 Catasetums went to death while all the others are doing fine, and that it is a fimbriatum which normally can stand these temps.