|b| \leq\ 55\arcdeg$. There were 143 observations in this region of the sky, which we inspected for usable spectra.

Each observation includes data from the three active X-ray Imaging Spectrometer (XIS) detectors on board *Suzaku* [@koyama_etal07]. The detectors each have an $18\arcmin \times 18\arcmin$ field of view and a point spread function of $\approx 2 \arcmin$. We only considered data from the back-illuminated XIS1 detector since it has a larger collecting area below 1 keV than the other detectors.

We processed all XIS1 data using HEAsoft version 6.17 and calibration database (CALDB) files from 2015 January. We followed the standard data reduction procedure described in *The Suzaku Data Reduction Guide*.[^3] This includes recalibrating the raw data files, screening for flickering or bad pixels, energy-scale reprocessing, and building good time interval (GTI) files. Fortunately, the FTOOL script `aepipeline` performs all these tasks for standard *Suzaku* observations. We used `aepipeline` version 1.1.0 to generate reprocessed images, light curves, and spectra for our analysis.

We extracted all data products using `xselect` version 2.4. Each data set combined data from $3 \times 3$ and $5 \times 5$ editing modes where applicable. We did not impose any non-standard criteria on the data extraction steps with 