Figure 2: ASD vs Frequency to compare possible changes in the violin modes for the two times from above. Note: BNS Range y-axis units not shown for viewing clarity. We tracked down the time for one of the louder Pizzicato glitches from this day, a 1023 Hz glitch from 07:46 UTC, and then found a time within the same lock stretch where there are no glitches near that frequency, 03:00 UTC. Figure 1: Livingston BNS Range (blue line) placed over the glitchgram (dots) for this day.

The ASD shows us the average amount of noise in the detectors at any given time. 2 below), which shows us the Amplitude Spectral Density (ASD) versus frequency. We then plotted data from these times as a spectrum (Fig. We did this by first finding a time where a Pizzicato glitch was seen, and then picking a nearby time where there were no nearby glitches (Fig. Since these glitches are present in the same frequency ranges that Violin Mode Harmonics glitches take place in, the first thing we checked was if Pizzicato glitches were directly correlated to the violin modes being excited. Excitations around 500 Hz are First Order Violin Modes, 1000 Hz are Second Order, and 1500 Hz are Third Order Violin Modes. These excitations manifest in the fibers at around 500 Hz and, depending on how strong these excitations are, can cause vibrations at higher frequencies, similar to how plucking a violin string can cause reverberations at multiple frequencies. Violin modes occur when the glass fibers that hold up the test masses (the mirrors that we bounce lasers between to measure gravitational waves) in the detectors experience excitations from changes in temperature. This glitch is so interesting to us primarily because it so clearly seems related to the violin modes of the test mass suspensions, but at the same time we haven’t yet been able to pinpoint an exact cause. They showed up in both detectors within months of each other however, since we have seen possible previous incarnations of Pizzicato (see Church), we cannot be certain that whatever is causing these glitches is something completely new to the detectors. About 80% of these glitches are found at the Livingston detector, with the other 20% occurring at Hanford. Pizzicato first showed up during Engineering Run 14 (ER14), and continued to the end of O3.

Pizzicato glitches typically resemble a UFO and show up within the frequency ranges of First Order (~500 Hz) and/or Second Order(~1000 Hz) Violin Modes. Pizzicato was brought to our attention when it was proposed as a new glitch class by She, along with the help of other users, is ultimately the reason why Pizzicato has been added as a new category. Pizzicato (originally known as High Frequency Burst 500 Hz) has been added as a new glitch category option in Level 5 and Level 7!

Not pizzicato