jeffrey.kissel@LIGO.ORG - posted 11:50, Thursday 07 February 2019 - last comment - 10:24, Thursday 21 February 2019(46847)
PCALY Showing Signs of Clipping (Because it's very cold outside again?)
J. Kissel, The H1 DARM figure of merit on the wall constantly shows the H1 PCALY PX PD ASD calibrated into displacement, so it's easy to notice when it looks abnormal. Today (and for the past several days), the I've noticed that other peaks in the ASD besides those requested by calibration lines have returned, reminiscent of very-cold winter problems from 2017 (see LHO aLOG 33108, and FRS Tickets 8328 and Integration Issue 8481). Note that temperatures are also quote cold today, in the ~15 deg F range. This is to notify the PCAL team to investigate. Also @DetChar, the summary pages for the PCAL system, e.g. the 2019-02-05 PCAL Summary page appears to have a significant flaw in he calibration of the X- and Y-end ASD, off by a factor of about 1000. Further, the last two days on summary have failed, and the "clipping" pages (2019-02-06) are dead and/or a repeat of each other.
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Still clipping. Interestingly (?) a few peaks have changed location. The main feature at 27.6 Hz is a little bit worse. There is no coherence with DARM (even though the ASD reports that the "displacement" is only a bit away from DELTAL EXTERNAL, and there's a completely coincidental feature around that frequency), so this is likely clipping on the RXPD side of things again.
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Associated with FRS Ticket 12281.