¶ Air Compressor (50 Hz)
Description:
Air Compressor (50 Hz) are short glitches centered at a frequency of 50Hz.
Cause:
At LIGO Hanford, these glitches were found to be related to air compressor motors switching on and off at the end stations. These were solved on 29 September 2015 at LIGO Hanford by replacing the vibration isolators (rubber feet) on air compressors. However, a few weeks' worth of these glitches were in data from the first observing run (O1) prior to the fix.
Status:
Extinct.
Examples:
Audio Example:
Make sure to wear good headphones!
More Information:
- LIGO Hanford electronic logbook entry from 12 September 2015
- LIGO Hanford electronic logbook entry from 29 September 2015
- LIGO Hanford electronic logbook entry from 30 September 2015
- During later observing runs, other causes have produced glitches at similar frequencies, often of somewhat longer durations. See, for example, Slow Parallels.