Chandra Calibration StatusChandra Calibration Status

Gain correction files for epochs 35 (Aug. – Oct. 2008) and 36 (Nov. 2008 -Gain correction files for epochs 35 (Aug. – Oct. 2008) and 36 (Nov. 2008 -Jan.2009) were released in CALDB versions 4.1.0 and 4.1.2.Jan.2009) were released in CALDB versions 4.1.0 and 4.1.2.

There have been 3 CALDB releases since the last CUC meeting

CALDB 4.1.0 Dec. 15, 2008

CALDB 4.1.1 Jan. 21, 2009

CALDB 4.1.2 Mar. 27, 2009.

HRMA encircled energy fraction released in CALDB 4.1.0 for use with mkpsfmap.

Updated HRMA effective area released in CALDB 4.1.1

HRMA

ACIS

HETG

Updated HETG transmission efficiencies were released in CALDB 4.1.1

Two corrections were applied to the predictions of the raytrace code Two corrections were applied to the predictions of the raytrace code before CALDB 4.1.1before CALDB 4.1.1

Empirical XRCF correction

HRMA overlayer of 22A

Updated HRMA Effective Area

Re-Analysis of the Ground-Based (XRCF) Data

HETG Continuum Measurement SSD Continuum Measurement

Empirical Correction to Updated HRMA Effective AreaEmpirical Correction to Updated HRMA Effective Area

XMM-Newton / Chandra Cross-Calibration

Do the mirror shutters block a greater fraction of the beam than presently predicted by Do the mirror shutters block a greater fraction of the beam than presently predicted by the raytrace code – Analysis of HSI ring focus images show that the shutters reduce the raytrace code – Analysis of HSI ring focus images show that the shutters reduce the throughput of the mirrors by at most 1%.the throughput of the mirrors by at most 1%.

Is a greater fraction of the beam scattered beyond the 2mm pinholes used for Is a greater fraction of the beam scattered beyond the 2mm pinholes used for effective area than presently predicted by the raytrace code – The measured effective area than presently predicted by the raytrace code – The measured 2mm/35mm flux ratio is consistent with the predictions of the raytrace code below 2 2mm/35mm flux ratio is consistent with the predictions of the raytrace code below 2 keV and is approximately 3% less than the value predicted by the raytrace code at 6 keV and is approximately 3% less than the value predicted by the raytrace code at 6 keV.keV.

Improve the pile-up correction for the SSD continuum measurements.Improve the pile-up correction for the SSD continuum measurements.

Investigate the discrepancy between FPC and SSD measurements.Investigate the discrepancy between FPC and SSD measurements.

Current HRMA Calibration

HIS Ring Focus Images

Improve the pile-up correction for the SSD continuum measurements.Improve the pile-up correction for the SSD continuum measurements.

Investigate the discrepancy between FPC and SSD measurements.Investigate the discrepancy between FPC and SSD measurements.

Measured FPC 2mm/35mm flux ratio vs. energy

Update on the ACIS Contamination ModelUpdate on the ACIS Contamination Model

ACIS Calibration Status

Spectrum of ECS L-ComplexSpectrum of ECS L-Complex

F-K edge

ECS data fit with the old and new spectral model for the L-complexECS data fit with the old and new spectral model for the L-complex

Old Spectral ModelOld Spectral Model New Spectral Model

Decline in ECS Flux with TimeDecline in ECS Flux with Time

Optical depth of the contaminant at 700 eV on ACIS-SOptical depth of the contaminant at 700 eV on ACIS-S

Optical depth of the contaminant at 700 eV on ACIS-IOptical depth of the contaminant at 700 eV on ACIS-I

Revised HETG Efficiencies

CALDB 4.1.1

HRC-I/ACIS Cross-Calibration with Updated HRMA Model

HRC-S QE Re-CalibrationHRC-S QE Re-Calibration HRC-S 0.5-10keV QE HRC-S 0.5-10keV QE

calibrated and fine-tuned in-calibrated and fine-tuned in-flight using LETG blazar flight using LETG blazar continuacontinua

HRMA EA revision requires HRMA EA revision requires QE re-calibrationQE re-calibration

Account for:Account for:– HRMA EA changes HRMA EA changes

– Accumulated in-flight data Accumulated in-flight data suggesting overly-hard power-suggesting overly-hard power-law indices than HETG+ACIS law indices than HETG+ACIS by of order 5%by of order 5%

– Will require relative QE Will require relative QE correction between ~0.5-5keV correction between ~0.5-5keV of ~15%of ~15%

Power law Fits to contemporaneous HETG Power law Fits to contemporaneous HETG and LETG observations of PK2155-304and LETG observations of PK2155-304

Complicated by:• Spectral shape/intensity variability• Parameter non-orthogonality• Possible PL curvature

LEG

HEG

MEG

CUC Calibration Wish List

1) Astrometric Calibration

Do observers have ready access to any study of the astrometriccalibration of the mission PSF tools, e.g. if a field of sourceswith well-known positions is both observed and simulated by thePSF tools, how well do the observed and simulated data sets line up?

Astrometry - The overall 90% uncertainty in absolute positions is 0.6”. This is given on the CXC web pages and in the POG. The mean off-set between CSC and SDSS positions is 0.2”

On-axis PSF - There are several on-line Chandra calibration workshop presentations as well as a discussion in the POG on this topic.

The CSC Catalog Statistical Characterization memo shows that the uncertainties in relative astrometry for bright point sources is 0.2” within off-axis angles of 10’ and approximately 1” at larger off-axis angles.

A study has begun to simulate a Chandra observation of the open star cluster NGC2516 with SAOTrace and then compare the x-ray source positions as determined by wavdetect with the optical positions.

2) ACIS Bad Pixel Table

Data discarded via entries in the ACIS Bad Pixel Table (obviously)reduces the effective area of the mission.  Currently, the standardBad Pixel Table aggressively removes ACIS columns and is not necessarilyappropriate for all kinds of ACIS science.  Modifications to the ACISBad Pixel Table should pass through an approval process which includesconsultation with the Users Committee.  Several different ACIS Bad PixelTables, each optimized

Data systems is revising the CIAO tool acis_build_pixel so the user

has much more freedom in specifying the bad pixels.

3) RMFs and ARFs

Users need the capability of creating RMFs and ARFs for user-selectedgrades.  There are several benefits:  - for bright piled-up sources filtering on only single events will    in general reduce pileup  - for faint non-piled-up sources a non-standard grade selection    can increase effective area  - for bright non-piled-up sources a non-standard grade selection

    may improve energy resolution.

Since the Chandra beam is comparable to the size of an ACIS pixel, grade 0 events are not necessarily un piled-up.

The standard grade set is 02346. In general, grades 1 and 5 add about 1-2% to the standard grade set. For soft sources, grade 7 is heavily dominated by charged particles. For photon energies greater than 6 keV, grade 7 events can add an additional 10% to the standard grade set, however the background rate is 75 times higher when including grade 7 events.

ACIS Flight Grades Grade 0 – single pixel

Grade 1 – Diagonal split

Grade 2 – vertical split

Grades 3 and 4 - horizontal splits

Grade 5 – L-shaped + corner

Grade 6 – L shaped

Grade 7 – everything else

Grade 0 fraction vs. count rate

E0102-72E0102-72.

ACIS-I3 ACIS-S3Grade 02346 1 Grade 02346 1

5 7 5 7

ECS Data

G21.5-09G21.5-09.

ACIS-S3

E0102-72E0102-72.

ACIS-S3 ACIS-I3

Cas ACas A.

ACIS-S3 ACIS-I3

4) ACIS Contamination Model

5) Soft Proton Contamination

Proper statistical treatment of backgrounds requires a model of thebackground spectrum, but what is this for the soft proton contamination?In addition, what is the spatial distribution of the soft protoncontamination? Is it uniform, or is it vignetted at all by the HRMA?

The most common type of BI flare is very well-behaved, has a reproducible spectrum (a power law with an exponential cutoff (see Markevitch et al. 2003, ApJ 583, 70), and a spatial distribution that is non-uniform but energy-independent.

These results were presented at the 2003 Chandra Calibration meeting

(http://cxc.harvard.edu/ccr/proceedings/03_proc/presentations/markevitch2/s005.html)

This information can be added to the CIAO thread for generating background images for extended sources. We can also provide a tool which will add in the background flare component in a blank sky image.