Where did this piece go?

Fortunately I'm not holding a large bolt in my hand and asking the engineers if they know which bit of the telescope it came from. Our engineering team put everything back together so precisely after our recent realumunisition work (see here and here) that tonight it was hardly necessary to make any adjustments at all in order for us to take science data again. We were doing science observations just an hour after sunset on our first night back when in fact we had scheduled two and a half nights of engineering to get us up to speed again!

We still have to do some very careful realignment which we're doing now as the telescope structure has cooled off sufficiently to give us stable conditions. In another hour I'll start doing the sums to make sure both the primary and secondary mirrors are aligned correctly and that they also make the proper corrections depending where on the sky we are pointing. Just the sort of thing you want to do be doing at two o'clock in the morning at 14,000 feet...

We should be fully back in business at the start of tomorrow night I'm pleased to say.