HRC-I Gain Maps

A new time-dependent gain correction for HRC-I data was introduced in CALDB 4.2.0 on 15 December 2009. These new gain maps are based on the scaled sums of the three nearest amplifier signals to the event location, which results a more accurate gain correction. (PHA is the sum of all amplifier signals corresponding to the event in question, and has a much larger small-scale spatial variation than the SUMAMPS metric.)

The gain maps were updated in CALDB 4.4.1 (15 December 2010) and CALDB 4.4.7 (15 December 2011). Technical details on the new gain maps are described in the memo SUMAMPS-based Gain Maps for the HRC-I.

Users working with HRC-I data should reprocess to improve the gain calibration in their data by running the chandra_repro script or by following the Create a New Level=2 Event File thread.