Dramatic Improvement of RXTE Background Models for Faint Sources

A patch to FTOOLS 4.1, released June 26, 1998, includes an updated pcabackest a nd new models which provide significant improvement in the PCA background subtraction for faint sources. In addition, fixes to several known bugs are included and a new xtefilt which provides better filtering capabilities .

RXTE users with epoch 3 data at count rates below 40 ct/sec/PCU should install this patch and reanalyze their data to take advantage of the dramatic improvement. The new models provide reliable background subtraction below 24 keV for energies where the net signal is > 0.01 ct/sec/keV.