Today's activities:
- The relay tube was installed, and was leak checked: no leaks bigger than 1E-10 Torr have been detected
- The HAM5/HAM6 annulus system is being pumped down. The Turbo backing line is already at around ~4E-5 Torr
- The Mobile pumping station with 2 pcs. of ISP1000 pumping carts and with the mobile transformer has been installed next to the OMC Turbo station (see picture, and see the PID according to LIGO-E2300443-v1 Main volume Double Mobile Scroll Turbo Startup Procedure, Appendix II.)
- The checklist for pumpdown has been done according to LIGO-E2300169-v2
- The dew point at the OMC venting port in the chamber was measured -38.9 deg C, which is surprisingly good (details: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=79483)
- The pumpdown of the corner has started. With the Double ISP-1000 carts it is pretty quick: the pumpdown started at 16:15, and at 19:07 the pressure is already 167 Torr, which means 1900 l/min (at the Turbo station, as the pressure is already <100, it is well over 2000 l/min, as it should be)
- The pumpdown of HAM7 has also started, it is pretty fast, as it was anticipated, since no doors were opened there. It is already at 1.2E-5 Torr. See details here: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=79482

As you can see in both pictures, the HAM5-HAM6-HAM7 area is very busy with vacuum equipment, so please only go there if it is absolutely necessary, and if you do, be very careful. Especially the Pfeiffer pumping carts can tip over easily (remember last pumpdown), and in general, Turbo pumps don't like movement - they can easily trip off. Now there are 2 Pfeiffer pumping carts, 3 more small Pfeiffer turbos, a leak checker, a supersucker cart, the new double ISP-1000 mobile pumping station, and the HAM7 turbo up and running.

There were a couple of other issues, too:
- The PT-154 (MKS) gauge, between HAM7 and BSC3 on the FCT, falsely shows 1E-3 Torr. It needs replacement, which will be done after O4
- The instrument air compressor failed to switch on one more time at around 16:45. The aLog about the last failure is here: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=79443. It was restarted with some struggle, but it seems that the only real solution is to replace it. A Nitrogen and a compressed air bottle was staged in the mechanical room, just in case