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CalDB Public Release Notes
Version: 3.2.2
Effective Date: (UTC) 2006-05-03T15:00:00

Installed in Standard Data Processing (SDP) as of (UTC) 2006-05-03T16:30:00 (12:30pm)
Release to public (anticipated) Tuesday 2006-05-09.

I. Overview

CalDB 3.2.2 is a small patch to CalDB 3.2.1 which includes three new T_GAIN files corresponding to two new epochs (to wit, quarter years) of the mission timeline. These are Epochs 23 and 24, which cover the August 2005 - Jan 2006 time period.

II. Summary of Changes

A. T_GAIN files for EPOCHs 23 and 24.

    acisD2005-11-01t_gainN0002.fits    (Flat, non-interpolating file, will be current in SDP)

ECS data collected from May 01 2005 through Nov 01 2006 have been reduced to determine the chip-by-chip T-Gain or time-dependent gain correction factors for those periods. The Chandra Data System team has produced the resultant CalDB FITS files for use in CIAO/SDP ACIS Level 1 tool acis_process_events that are effective on the dates in the filenames above.

These new files upstage and demote the previous standard processing default file, acisD2005-05-01t_gainN0002.fits for all observations taken on or after UTC=2005-05-01T00:00:00.

Pipes/Tools affected:
ACIS L1 pipeline tool acis_process_events.

CIAO tools affected:
ACIS L1 events file generator

Threads affected:

Create a New Level=2 Event File
Apply the Time-Dependent ACIS Gain Correction

III. Technical Details

An improved means of filtering the input ECS data to exclude out-of-bounds temperatures has been employed for these epochs relative to the preceding T_GAIN data releases. For the files in question, the time-dependent gain correction has the following disposition versus energy for chips ACIS-I3 and ACIS-S3, respectively. The previous default file, namely acisD2005-05-01t_gainN0002.fits, a non-interpolating file released in CalDB 3.2.0, Nov. 15, 2005, is included in the plot for reference. Note that for the FI chip I3, the T_GAIN correction is not monotonically increasing versus epoch during 2005.

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Fig 1: ACIS-I3 aim point time-dependent gain correction in eV.

I3 T_GAIN N0005 Epochs 23 and 24

Fig 2: ACIS-S3 (BI chip) time-dependent gain corrections derived from the new data files.

S3 T_GAIN N0005 Epochs 23 and 24

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