We've been struggling a bit lately to use the ITMY green camera for initial alignment. I'm suspicious that when I adjusted the masks (that exclude everything but a circle, before doing the centroid calculation) I didn't make them big enough. Mask adjustment alog is 58447. They're fine for when we're already aligned, but perhaps there is clipping that is going on that is making the calculated alignment error signals not as useful. The attached screenshot shows our 'starting' place with one of our initial alignments this morning, and it seems likely that this clipping on the mask is causing confusion for the error signals.
While we were waiting for the ITMY ring heater to cool a bit, I tried moving ITMY while the ETM & TMS WFS were running, to see how the camera error signal changed, while I was also watching the camera image itself. The error signals seemed to respond pretty normally, so no surprises there. After I had gotten the beam pretty close to the old position from alog 58447, I effectively removed the mask by making its radius 2030 pixels (rather than the 230 it had been). When I reloaded the camera config, I didn't see any change, although since I had already moved to where I wasn't clipping on the mask that's also not surprising.
I'm leaving the mask off for now (well, the radius gigantic), and I'll have a look once we're fully aligned at 2W. It's possible that we'll need to take Richard up on his offer to zoom out of those cameras a bit, if the spots that we like now are close to the edge of the camera view.
Also, TJ and I were chatting, and maybe it should be possible to add something from Guardian to trigger a camera snapshot to be taken? I was lamenting that I didn't know if the hourly snapshots would have caught the moment of our having reset the green references whenever we last did that, since it's unlikely that we happened to be at the final alignment at the moment of the hour that the snapshots are taken. Or, we can just try to remember to take snapshots of the ITM green cameras when we reset initial alignment references.
Once the IFO was aligned at 2W DC readout, I opened the green shutters. Yarm didn't want to lock on the 00 mode for me, but Xarm did, and as you can see in this attached screenshot, we're a little close to the bottom of the camera view (this screenshot is without the mask). So, probably we'll want to zoom out on these green ITM cameras.
That said, I am interested in seeing if we can limp along for the last week and a half of our commissioning period without adjusting the cameras. We should discuss at our 1pm meeting today.
