The SWIFT BAT Software Guide Version 6.3 30 ... - HEASARC - Nasa

64 CHAPTER 6. BAT ANALYSIS ISSUES
6.3.6 batbinevt: light curves have slightly incorrect energy bins
Task: batbinevt
Version: v1.28 and earlier
What builds: HEADAS 6.0.4 and earlier
Problem: Incorrect energy bin assignment for light curves
Status: Closed (HEADAS 6.0.5)
Updated: 29 May 2006
The task batbinevt is used to make spectra and light curves from BAT data. A bug in the way
that energy bin assignments are made will lead to slightly incorrect reported count rates.
The easiest way to explain it is by example: if you ask for a light curve from 15-25 keV, then
you actually get a light curve from 15-25.1 keV (not the extra 0.1 keV). The upper bin edge will
always be too large by 0.1 keV.
If you are making a vector light curve (multiple energy bands), or a spectrum, then only the
last energy bin is affected.
Thus, this is typically a small effect: spectra are basically unaffected (since the top bin is usually
ignored). Light curves made in individual bands are affected. However, for wide energy bins, the
light curves will be off by only a small amount (