After H1's longest lock of O4 thus far (60hr29min Lock from 8/23(wed) 1020amPT -- 8/25(fri) 11pmPT), H1 has has been finicky with locking and also has had a degrading inspiral range. 

The primary issue prior to this lockloss was the EY temperature increase of 3+degF due to FAILURE of Chiller Pump #1 at EY.  From about 10am-5pm the temperatures were NON-nominal (but H1 remained locked this whole time(!) as ASC maintained the pointing for EY during this HUGE temperature swing).

With that said about the temperature drift, and at TJ's request, wanted to also list Commissioning changes which occured during the 2.5days of the lock.

(Times in PT)

Aug23 (Wed)

• 1020amLocal:  H1 60hr lock BEGINS
• HAM1 in-air ground L4C HEPI Feedforward filter + gain change (332pm alog 72393, Jim)
• PCALY 17.1Hz Cal Line Amplitude Reduced (355pm alog 72394, Louis)

Aug24 (Thurs):  Nothing in alog

Aug25 (Fri)

• 10am-5pm EY Chilled Water Pump #1 FAILED & temperature in the LVEA drifts on order of 3 degrees farenheit over the cours of most of the day shift. (530pm alog 72444, tyler)
• MICH Feedforward filter change (2pm alog 72430, gabriele)
• HAM1 in-vac L4Cs ASC FF filters updated (324pm alog 72432, Elenna)
• ~11pmLocal H1 60hr lock ENDS

Aug26 (Sat)

• Lockloss recovery late Fri night & Sat morning (before midnight Fri, alog 72440, Austin, Tony)
  • dither script run 
  • changing sliders to a previous initial alignment of gps time 1376843785 (finally helped with ALSy)
  • turning off ALSy WFS for 5 secs at beginning of lock (alog 72460)