CalDB 4.11.1 Public Release Notes

I. INTRODUCTION

CalDB 4.11.1 is an upgrade to the Chandra CalDB, which includes the following items:

• ACIS CTI Corrections version N0012
• HRC-S QE Uniformity File Set N0018
• ASPECT ACA-P Dark Current Update #6

For the CIAO 4.16 / CalDB 4.11.1 release notes see How CalDB 4.11.1 Affects Your Analysis.

II. SUMMARY OF CHANGES

A. ACIS CTI Corrections version N0012

Location:	$CALDB/data/chandra/acis/cti/
Filenames:	acisD2005-01-01ctiN0012.fits acisD2005-09-16ctiN0012.fits acisD2010-01-01ctiN0012.fits acisD2015-01-01ctiN0012.fits acisD2020-01-01ctiN0012.fits

Calibrations for "warm" FP_TEMPs have been generated for chips ACIS-S2 and ACIS-S3. Five new files have been generated, upstaging the corresponding existing N0011 files with the same effective dates, beginning with the 2005-01-01 file.

Version N0012 of the CTI correction file contains improved CTI corrections for all four chips on ACIS-I up to focal plane temperatures of -107C. No changes are made for data taken with FP temperatures below -117C, or prior to 2005. The CTI corrections for ACIS-S0, S1, S4, and S5 are unchanged.

Prior versions of the CTI correction file used a linear correction with temperature, a single energy-dependent correction at all temperatures, and a single trap map at all temperatures. Version N0011 uses a quadratic function to model the temperature dependence of the CTI correction, a separate power-law energy-dependent correction in each temperature bin, and a separate trap map in each temperature bin.

Hence the new CTI N0012 files have 3-D trap density map extensions, one for each chip. The four ACIS-I chips have multiple trap maps in each extension, i.e. 1024x1024xn, where n is 4 for ACIS-0 and ACIS-2 and 5 for ACIS-1 and ACIS-3. For ACIS S2 n=4, and for ACIS S3 n=1. The remaining ACIS-S chips have a single 1024x1024x1 trap map each. Each n, or index value covers a range of FP_TEMP values, from -125 C to -105 C.

See the ACIS CTI why page for more information.

PIPELINES/TOOLS AFFECTED:

ACIS L1 pipeline tool acis_process_events
CIAO reprocessing tool chandra_repro

THREADS AFFECTED:

Reprocessing Data to Create a New Level=2 Event File

B. HRC-S QE Uniformity File Set N0018

Location:

$CALDB/data/chandra/hrc/qeu/

Filenames:

hrcsD1999-07-22qeuN0018.fits hrcsD2000-01-01qeuN0018.fits hrcsD2001-01-01qeuN0018.fits hrcsD2002-01-01qeuN0018.fits hrcsD2003-01-01qeuN0018.fits hrcsD2004-01-01qeuN0018.fits hrcsD2005-01-01qeuN0018.fits hrcsD2006-01-01qeuN0018.fits hrcsD2007-01-01qeuN0018.fits hrcsD2008-01-01qeuN0018.fits hrcsD2009-01-01qeuN0018.fits hrcsD2009-09-15qeuN0018.fits hrcsD2010-09-14qeuN0018.fits hrcsD2012-03-29qeuN0018.fits hrcsD2012-10-05qeuN0018.fits hrcsD2013-09-21qeuN0018.fits hrcsD2015-02-17qeuN0018.fits hrcsD2016-02-22qeuN0018.fits hrcsD2016-07-29qeuN0018.fits hrcsD2017-01-25qeuN0018.fits hrcsD2017-06-06qeuN0018.fits hrcsD2017-09-27qeuN0018.fits hrcsD2018-01-20qeuN0018.fits hrcsD2018-05-27qeuN0018.fits hrcsD2018-09-27qeuN0018.fits hrcsD2019-02-25qeuN0018.fits hrcsD2019-08-23qeuN0018.fits hrcsD2020-01-18qeuN0018.fits hrcsD2020-07-23qeuN0018.fits hrcsD2021-05-14qeuN0018.fits hrcsD2021-09-03qeuN0018.fits hrcsD2022-09-09qeuN0018.fits hrcsD2023-09-08qeuN0018.fits

A new set (version N0018) of the HRC-S QEU files has been generated, including a new file effective 2023-09-08, derived from the most recent HZ43 LETG/HRC-S observations. The wavelength- independent drop in QE since last June is from 1-2%, depending on dispersed orders. The wavelength-dependent corrections required on S1 and S3 continue to follow long-observed trends.

See the HRC QE / QE Uniformity why page for more information.

PIPELINES/TOOLS AFFECTED:

The SDP pipeline procedure tg_mk_responses is used to generate single-source GARFs and GRMFs for HRC-S/LETG observations, to be ingested onto the archive. This procedure uses the HRC-S QEU library as loaded from the ARDLIB.

See the CIAO scripts mktgresp, and fluximage, this latter which uses mkinstmap.

THREADS AFFECTED:

For exposure-corrected imaging analysis with HRC-S, see the thread:

• HRC-S Exposure Map and Exposure-corrected Image

For grating spectroscopy with the LETG/HRC-S, see the thread:

• LETG/HRC-S Grating ARFs

C. ASPECT ACA-P Dark Current Update #6

Location:	$CALDB/data/chandra/pcad/dark_curr/
Filenames:	acapD2023-11-07darkN0002.fits acapD2023-11-25darkN0002.fits acapD2023-12-06darkN0002.fits acapD2023-12-24darkN0002.fits acapD2024-02-06darkN0002.fits acapD2024-03-09darkN0002.fits

The CXC Aspect Team has generated a sixth set of ACAP DARK_CURR files, including six (6) new files, to support ACA background calculation and subtraction in the ASPECT L1 pipeline. The DARK_CURR files draw on an ever-growing database of ACA full field dark current data products which have been accumulated since the 1999:223 OAC dark current pixel map. Each version N0002 dark current fits file in the CALDB includes a 1024x1024 image with the processed full-field dark current map of the ACA CCD in e-/sec. Each file also includes header information with the ACA CCD temperature of the calibration, the reference date of the ACA dark current product, and the scale expected to be used to scale the calibration e-/sec to the effective e-/sec at the observed temperatures during observations.

The DARK_CURR files have effective dates (Cal Validity Start Date, or CVSD*) which are spaced ~2-6 weeks apart, similar to their previously released datasets. The new files are effective as of the respective dates given above. These new files extend the date coverage for archival observations through 2024-03-09T00:00:00, with the final file being the one that will be the default file in standard data processing (SDP) until the next release/extension.

PIPELINES/TOOLS AFFECTED:

PCAD L1 Pipeline tool asp_get_calib calls for the ASPEC CalDB files, including DARK_CURR.

THREADS AFFECTED:

None.

III. TECHNICAL DETAILS

B. HRC-S QE Uniformity File Set N0018

A new version of the HRC-S QEU file set (N0018) has been generated for release in CalDB. This version adds a new QEU file, effective 2023-09-08T00:00:00 UTC, based on the most recent HZ 43 observation. The wavelength-independent drop in QE since last June is from 1-2%, depending on dispersed orders. The wavelength-dependent corrections required on S1 and S3 continue to follow long-observed trends.

This version can completely replace all previous distributed CalDB versions, which can then be removed from the CalDB distribution. Fig. 1a-d below gives wavelength-dependent corrections applied to each file (the black traces are for S1, the red for S3).

Fig. 1a: HRC-S QE Uniformity corrections used in the six N0018 files dated 2009 - 2013.

Fig. 1b: HRC-S QE Uniformity corrections used in the six N0018 files dated 2016 - 2017.

Fig. 1c: HRC-S QE Uniformity corrections used in the six N0018 files dated 2018 - 2020.

Fig. 1d: HRC-S QE Uniformity corrections used in the four N0018 files dated 2021 - 2023.