Last modified: 10 December 2021

URL: https://cxc.cfa.harvard.edu/caldb/prop_plan/pimms/pimms.html

Cycle 24 PIMMS Effective Area Public Information

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Released as of 15 DEC 2021



The Chandra effective areas are built for sixteen configurations implemented in the PIMMS EA viewer and count rate calculator facility. Four of the configurations are for the default aim-point positions for each of the four detector arrays aboard Chandra, specifically the ACIS-I, ACIS-S, HRC-I and HRC-S routines.

The other twelve configurations involve one or the other of the transmission gratings. For the HETG/ACIS-S configurations the default SIM_Z positions do not correspond to the above aim point settings, but instead are offset to minimize the ACIS CTI effect. A default SIM_Z offset of -3.0 mm (in the direction of the readouts) is used for HETG/ACIS-S.

As in previous years, model observations have been selected so that the zeroth order ARFs, as well as the first order GARFs will correspond to the appropriate positions on the ACIS-S array. The same is true for the LETG/HRC-S configuration, where the default zeroth order position does not necessarily coincide with the default imaging aim point.

PIMMS effective area (EA) files are built using model observations (OBSIDs) with standard/default detector and SIM_Z configurations with the CIAO 4.14 routines mkarf for imaging aimpoint cases and mkgarf for gratings configurations, using the most current CALDB input files (CALDB 4.9.6). The following table gives the input CALDB file information used by mkarf or mkgarf to generate the respective effective area files (as ARFs) for the Cycle 23 (N0023) and Cycle 24 (N0024) proposal cycles. Plots of the PIMMS effective areas may be viewed at the PIMMS Effective Area Data page. You may also use the automated Chandra Effective Area Viewer.

PIMMS Input Data and Procedure Changes for Cycle 24:

CalDB Input File Uprades (since Cycle 23):

  1. CIAO 4.14 vignet correction sign error bug fix (ardlib): A software error has been identified in the vignetting correction in the ARDLIB tools, which has been corrected in the CIAO 4.14 pre-release software, used to generate the new PIMMS EAs. This change should have the most significant effect for off-axis ARFs and exposure maps. The fix causes only a slight change in any of the sixteen PIMMS effective area configurations (less than a 1% reduction).

  2. AIMPOINT Configurations: ENERGY GRIDS All the grids for the aimpoint configurations match the default energy grid of the LETG first order for that detector array; for the HRC-I, the grid corresponds to the LETG/HRC-S first order default grid. Hence, for ACIS configurations, the aimpoint and zeroth order grids all have 8192 points. For HRC, the energy grids include 16384 points. The grids were changed for Cycle 21 in December 2018, to eliminate interpolation errors that occur when comparing spectra (and associated count rates) when comparing or calculating results across configurations.

  3. ACIS configurations: No new calibration file changes relevant to PIMMS Effective Areas have been made since the previous proposal cycle. The only change is due to the new time-delay setting that is relevant to Cycle 24. Specifically, the TIME delay qualifier for the effective areas has been adjusted for Cycle 24 to be 15 May 2023 UTC, or 800496069.184s MET. The result is that the Cycle 24 EAs for ACIS configurations a noticeable decrease in predicted EA below 1 keV compared with Cycle 23 for both ACIS-I and ACIS-S, to the level of ~-60% at the carbon K-edge and ~-38% at oxygen K.

  4. HRC-I configurations: An update to time-varying central QE has been released for HRC-I since the previous cycle, including a new file effective 2021-02-16T13:09:07 (UTC), calibrated for the new HV setting that is effective on that date (as of CalDB 4.9.6). Any changes relative to the previous cycle are due to that QE change, giving a flat ~8.2% increase (relative to CY23) below ~630 eV, and about ~3% increase above ~630 eV. The increase in the predicted value is again due to the new HV setting.

  5. HRC-S configurations: The HRC-S HV was reset on 2021-05-14T00:00:00, and new QE and QEU calibrations have been released (in CalDB 4.9.6) effective on that date. Both were employed in the Cycle 24 PIMMS EA derivations, and any differences between the Cycle 23 and Cycle 24 HRC-S configuration EAs is due to these upgrades. These changes produce a flat ~7.1% increase in the HRC-S-related PIMMS EAs over 60-630 eV, and decreasing to a <~2% increase at 10 keV (relative to Cycle 23).

Parameter Input Changes (versus CY23 inputs):

  1. Imaging aimpoints:Due to the thermal cycling of the Chandra Aspect Camera, the aimpoint drift has become irregular, and an operational scheme has been adopted to fix targets dynamically at the desired location. This results in a permanent aimpoint location for each chip as a matter of course (which may be changed programatically if necessary, but not due to drift. See the Table below, and the Proposers Observatory Guide (POG) Table 6.4. The permanent aim point locations were set for the Cycle 18 release, and remain so for the current cycle.

  2. ACIS CONTAM time-delay parameter: The CIAO ARF- and GARF-generating routines employ a time-delay option in the "detsubsys" parameter specification, wherein a TT date value in seconds may be entered to set the date for the time-dependent CONTAM calculations. For Cycle 24 the value is 800496069.184, which corresponds to UTC date 15 May 2023. For Cycle 23 the value was 768960069.184, corresponding to 15 May 2022. This affects all and only ACIS configurations.


TABLE 1

Configuration (CHIPX, CHIPY) ObsID Used HRMA QE QEU ACIS FI DEAD AREA ACIS CONTAM CONTAM TIME DELAY ACIS OSIP GREFF CALDB Filenames
ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
N/A N/A acisiD2020-11-17pimmsN0023.fits
acisiD2021-11-03pimmsN0024.fits
ACIS-S (210.0, 520.0) 9300 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
N/A N/A acissD2020-11-17pimmsN0023.fits
acissD2021-11-03pimmsN0024.fits
HRC-I (7590.0, 7745.0) 8531 hrmaD1996-12-20axeffaN0008.fits hrciD2020-02-20qeN0012.fits
hrciD2021-02-16qeN0013.fits
hrciD1999-07-22qeuN0002.fits N/A N/A N/A N/A N/A hrciD2020-11-17pimmsN0023.fits
hrciD2021-11-03pimmsN0024.fits
HRC-S (2095.0, 8915.0) 9630 hrmaD1996-12-20axeffaN0008.fits hrcsD2022-01-01qeN0015.fits
hrcsD2021-05-14qeN0016.fits
hrcsD2019-08-22qeuN0013.fits
hrcsD2021-05-14qeuN0015.fits
N/A N/A N/A N/A N/A hrcsD2020-11-17pimmsN0023.fits
hrcsD2021-11-03pimmsN0024.fits
HETG0/ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
N/A hetgD1996-11-01greffpr001N0007.fits acisihetg0D2020-11-17pimmsN0023.fits
acisihetg0D2021-11-03pimmsN0024.fits
HETG0/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
N/A hetgD1996-11-01greffpr001N0007.fits acisshetg0D2020-11-17pimmsN0023.fits
acisshetg0D2021-11-03pimmsN0024.fits
HEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acissheg1D2020-11-17pimmsN0023.fits
acissheg1D2021-11-03pimmsN0024.fits
HEGMEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acisshegmeg1D2020-11-17pimmsN0023.fits
acisshegmeg1D2021-11-03pimmsN0024.fits
MEG1/ACIS-S (211.2, 369.3) 7280 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits hetgD1996-11-01greffpr001N0007.fits acissmeg1D2020-11-17pimmsN0023.fits
acissmeg1D2021-11-03pimmsN0024.fits
LETG0/ACIS-I (970.0, 975.0) 9768 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acisiletg0D2020-11-17pimmsN0023.fits
acisiletg0D2021-11-03pimmsN0024.fits
LETG0/ACIS-S (210.0 520.0) 10662 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acissletg0D2020-11-17pimmsN0023.fits
acissletg0D2021-11-03pimmsN0024.fits
LEG1/ACIS-S (210.0 520.0) 10662 hrmaD1996-12-20axeffaN0008.fits acisD1997-04-17qeN0006.fits acisD2010-02-01qeuN0007.fits acisD1999-09-16dead_areaN0001.fits acisD1999-08-13contamN0014.fits 768960069.184
800496069.184
acisD2000-01-29osip_ctiN0006.fits letgD1996-11-01greffpr001N0007.fits acissleg1D2020-11-17pimmsN0023.fits
acissleg1D2021-11-03pimmsN0024.fits
LETG0/HRC-I (7590.0, 7745.0) 8531 hrmaD1996-12-20axeffaN0008.fits hrciD2020-02-20qeN0012.fits
hrciD2021-02-16qeN0013.fits
hrciD1999-07-22qeuN0002.fits N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrciletg0D2020-11-17pimmsN0023.fits
hrciletg0D2021-11-03pimmsN0024.fits
LETG0/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2022-01-01qeN0015.fits
hrcsD2021-05-14qeN0016.fits
hrcsD2019-08-22qeuN0013.fits
hrcsD2021-05-14qeuN0015.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsletg0D2020-11-17pimmsN0023.fits
hrcsletg0D2021-11-03pimmsN0024.fits
LEG1/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2022-01-01qeN0015.fits
hrcsD2021-05-14qeN0016.fits
hrcsD2019-08-22qeuN0013.fits
hrcsD2021-05-14qeuN0015.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsleg1D2020-11-17pimmsN0023.fits
hrcsleg1D2021-11-03pimmsN0024.fits
LEGHI/HRC-S (2116.9, 8850.3) 331 hrmaD1996-12-20axeffaN0008.fits hrcsD2022-01-01qeN0015.fits
hrcsD2021-05-14qeN0016.fits
hrcsD2019-08-22qeuN0013.fits
hrcsD2021-05-14qeuN0015.fits
N/A N/A N/A N/A letgD1996-11-01greffpr001N0007.fits hrcsleghiD2020-11-17pimmsN0023.fits
hrcsleghiD2021-11-03pimmsN0024.fits

Notes for Table 1:

None.

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