Query times of valid data, hardware injections, and more.

Information about the state of the LIGO/Virgo data can be queried from resources at the GWOSC and from LVC-proprietary DQSEGDB through the functions of the pycbc.dq module. We will outline a few of common tasks below.

Determine the times an instrument has valid data

# Let's see when the detector was active.
# Note that all units are in seconds and that the +
from pycbc import dq
import pylab

start_time = 1126051217
end_time = start_time + 100000

# Get times that the Hanford detector has data
hsegs = dq.query_flag('H1', 'DATA', start_time, end_time)

# Get times that the Livingston detector has data
lsegs = dq.query_flag('L1', 'DATA', start_time, end_time)

pylab.figure(figsize=[10,2])
for seg in lsegs:
    start, end = seg
    pylab.axvspan(start, end, color='green', ymin=0.1, ymax=0.4)

for seg in hsegs:
    start, end = seg
    pylab.axvspan(start, end, color='red', ymin=0.6, ymax=0.9)

pylab.xlabel('Time (s)')
pylab.show()

(Source code, png, hires.png, pdf)

Finding times of hardware injections

# Let's see when the detector was active.
# Note that all units are in seconds and that the +
from pycbc import dq
import pylab

start_time = 1126051217
end_time = start_time + 10000000

# Get times that the Livingston detecot has CBC injections into the data
segs = dq.query_flag('L1', 'CBC_HW_INJ', start_time, end_time)

pylab.figure(figsize=[10, 2])
for seg in segs:
    start, end = seg
    pylab.axvspan(start, end, color='blue')

pylab.xlabel('Time (s)')
pylab.show()

(Source code, png, hires.png, pdf)

What flags can I query?

A list of many of the flags which can be quiered is available here. Instead, just give the raw name such as “DATA” instead of “H1_DATA”.

There are two additional types of flags which can be queried. These are the negation of the flags like “NO_CBC_HW_INJ”. The flag “CBC_HW_INJ” would give times where there is a hardware injection instead of times when there isn’t. Similarly if you use “CBC_CAT2_VETO” instead of “CBC_CAT2” you will get the times that are adversely affected instead of the times that are not.