If we assume that the intensity histogram of our wt data is a Gaussian curve, we can calculate sigma values based on the full width at half maximum (FWHM). The half peak diameter (HPD) of XRT at 1.5 keV is 18 arcseconds. After calculating the 95% and 99% confidence intervals in arcseconds, we settled on using a set value of 20 arcseconds for the radii of our sources (for filtering purposes).

GSFC’s Legacy FTP was still down, but Sandy found the files I needed on HEASARC. I downloaded and installed the latest Swift calibration files. I then processed all the XRT data for SGR 1900+14. I made light curves and spectra for all of the good pc and wt event files. My next steps are to model them to obtain best fits and to run an FFT on the wt data to obtain the spin period.