.. _gwpy-example-timeseries-statevector:

.. sectionauthor:: Duncan Macleod <duncan.macleod@ligo.org>

.. currentmodule:: gwpy.timeseries

Plotting segments for a `StateVector`
#####################################

Confident detection of gravitational-wave signals is critically dependent
on understanding the quality of the data searched.
Alongside the strain *h(t)* data, |GWOSC|_ also
releases a *Data Quality* :ref:`state vector <gwpy-statevector>`.
We can use this to check on the quality of the data from the LIGO Livingston
detector around |GW170817|_.

First, we can import the `StateVector` class:

.. plot::
   :context: reset
   :nofigs:
   :include-source:

   from gwpy.timeseries import StateVector

and download the state information surrounding GW170817:

.. plot::
   :context:
   :nofigs:
   :include-source:

   data = StateVector.fetch_open_data(
       "L1",
       1187008882 - 100,
       1187008882 + 100,
       verbose=True,
   )

Finally, we make a :meth:`~StateVector.plot`, passing `insetlabels=True` to
display the bit names inside the axes:

.. plot::
   :context:
   :include-source:

   plot = data.plot(insetlabels=True)
   ax = plot.gca()
   ax.set_xscale('seconds', epoch=1187008882)
   ax.axvline(1187008882, color='orange', linestyle='--')
   ax.set_title('LIGO-Livingston data quality around GW170817')
   plot.show()

This plot shows that for a short time exactly overlapping with GW170817
there was a data quality issue recorded that would negatively impact a
search for generic gravitational-wave transients (bursts).
For more details on this _glitch_, and on how it was excised, please see
the `Science Summary for GW170817
<https://www.ligo.org/science/Publication-GW170817BNS/>`__.