Extended Data Fig. 1: Illustration of the data cleaning prior to the imaging and spectral analysis.
From: X-ray polarization evidence for a 200-year-old flare of Sgr A*
Panel (a) shows the count rate in the 2–8 keV band (sum of three DUs, 200 seconds time bins) in the original data set that spans 2 million seconds. The two most intense spikes are associated with a geomagnetic storm. To illustrate less prominent variations, panel (b) shows a 300 kiloseconds-long portion of the same light curve that feature a number of smaller amplitude quasi-regular spikes (notice that the vertical scale has changed) that are mostly due to the South Atlantic Anomaly. The gaps in the light curves correspond to moments when the Galactic center was obscured by the Earth. Finally, panel (c) shows the count rate for the data cleaned from spikes and individual events that most plausibly are due to detector background rather than X-ray photons. The overall count rate in the cleaned data is almost a factor of two lower than in the original data.
