CalDB 4.6.10a Public Release Notes

I. INTRODUCTION

CalDB 4.6.10a is an upgrade to the Chandra CalDB, which includes the following items:

• ACIS SUBPIXEL BOUNDARY CONDITION MODS for CC-Modes

II. SUMMARY OF CHANGES

A. ACIS SUBPIXEL BOUNDARY CONDITION MODS for CC-Modes

Location:	$CALDB/data/chandra/acis/subpix/
Filename:	acisD1999-07-22subpixN0001.fits

With the installation of Standard Data Processing software version DS10.4.2, the appropriate CTI-correction for ACIS continuous clocking (CC-mode) data is being implemented in acis_process_events for the first time. As such, it becomes appropriate then to apply the ACIS SUBPIXEL repositioning (EDSER) algorithm to these data sets as well. This CalDB change is to add the CC33_GRADED and CC33_FAINT DATAMODE options to each of the ten headers of the above ACIS SUBPIX CalDB file in the keyword CBD20001. While this will apply the new CTI-correction algorithm to CC-mode data for the archive beginning on 2015-09-30T14:00:00, users will not have access to this software update in CIAO until December 2015. This means that reprocessing these CC-mode data sets with chandra_repro will remove the new CTI-correction and SUBPIX repositioning from them, until installing the December 2015 CIAO release on your local system.

See the ACIS energy-dependent pixel repositioning why page for more information.

PIPELINES/TOOLS AFFECTED:

ACIS Level 1 pipeline toolacis_process_events

THREADS AFFECTED:

Currently the CC-mode CTI-correction algorithm is not available in the CIAO acis_process_events, and it will not be available there until the December 2015 CIAO release. Hence no CIAO threads are affected by this change in CalDB until that next major CIAO release.

III. TECHNICAL DETAILS

A. ACIS SUBPIXEL BOUNDARY CONDITION MODS for CC-Modes

The specific header change for each of the ten extensions (one for each ACIS chip) is given below. Previously the second boundary condition in each header was set to:

CBD20001 = DATAMODE(FAINT,FAINT_BIAS,GRADED,VFAINT)

The new setting, with DS10.4.2, is as follows:

CBD20001 = DATAMODE(FAINT,FAINT_BIAS,GRADED,VFAINT,CC33_GRADED,CC33_FAINT)