I investigated the HWS glitching issue in more detail. I ran the following tests to try to reproduce the glitching seen previously:

1. Run each camera individually with the take command (number of ring buffers = 4): no glitching
2. Run each camera individually with the take command (number of ring buffers = 1): no glitching
3. Run both cameras at the same time with the take command (number of ring buffers = 1): no glitching
4. Run both cameras at the same time with the take command (number of ring buffers = 4): no glitching
5. Run both Run_HWS_ITMX and Run_HWS_ITMY at the same time: no glitching

Since we couldn't reproduce the glitching after everything restarted, Kiwamu and I decided that we create some Guardian diagnostics to run continuously on the HWS data. The following channels will be monitored and will issue warning in the case of aberrant behaviour:

• H1:TCS-ITMX_HWS_TOP100_PV: the mean value of the top 100 brightest pixels in counts - currently around 1040 counts for ITMX. This cannot exceed 4095 in a normal image. Corrupted images routinely show pixel values much larger than this. We can also monitor this to see if the value falls below a threshold (which it will do in the case of misalignments or SLED issues).
• H1:TCS-ITMX_HWS_LIVE_ACQUISITION_GPSTIME: the GPS time of the most recently recorded HWS image. If this falls more than 15 seconds behind the current GPS time, guardian can issue a warning.