next up previous contents
Next: Create the Photon Redistribution Up: Extract and Fit the Previous: Check for Pile Up   Contents

My Observation is Piled Up! Now What?

There are two ways to remove the effects of pile up from an observation:

Using the region selection and event file filtering procedures demonstrated in earlier sections, you can excise the inner-most regions of a source (as they are the most heavily piled up), re-extract the spectrum, and continue your analysis on the excised event file. For this procedure, it is recommended that you take an iterative approach: remove an inner region, extract a spectrum, check with epatplot, and repeat, each time removing a slightly larger region, until the model and observed distribution functions agree.


Using the event file filtering procedures, consider only the pattern 0 events (PATTERN==0). Pattern 0 events are less sensitive to pile up than other patterns.

Lynne Valencic 2011-07-26