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Chandra Instruments and Calibration

[*]Cal Home

[*]ACIS

[*]HRMA

[*]HRC

[*]LETG

[*]HETG

[*]Cross-Calibration Between Chandra and Other X-Ray Telescopes

[*]Aspect Information

[*]Calibration Workshop Index

[*]2001 Calibration Review

[*]2002 Calibration Workshop Proceedings

[*]2003 Calibration Workshop Proceedings

[*]2004 Calibration Workshop Proceedings

[*]2005 Calibration Workshop Proceedings

[*]2007 Calibration Workshop Proceedings

[*]SPIE Proceedings

[*]Science Requirements

[*]CALDB

  A high level overview of the instruments on-board the Chandra X-Ray Observatory can be found on the About Chandra pages and a more detailed description can be found in the Proposers' Observatory Guide . There are also several other sources of information for those observers interested in a more in-depth discussion of Chandra calibration issues, including: Current calibration data products for use in CIAO and other analysis systems can be found in the CALDB pages. A complete listing of all calibration products in the CALDB and a brief description of these products can be found in CALDB Products.

Calibration Requirements and Present Status

Prior to launch, a broad range of scientific objectives and calibration requirements were established for the Chandra mission. The table below gives a summary of the calibration requirements and the present calibration status. This table also gives our present goal for each of these calibration products taking into account the damage that has occurred to ACIS since launch (i.e., radiation damage and contamination build-up on the filters) and our improved understanding of the instruments. More detailed information on a given calibration characteristic can be found by clicking on that item in the "Characteristic" column.
Characteristic Det/Grat Requirement Present UncertaintiesGoal
(1 σ ) (CIAO 4.0 with CALDB 3.4.2)  
Absolute Positions HRC/ACIS 1.0" 0.6" (90%) 0.6" (90%)
Relative Spatial PositionsACIS-I 0.1" 0.1" 0.1"
ACIS-S3 0.1" 0.1"
HRC-I 0.3" 0.1"
Absolute Energy Scale ACIS 1 eV 0.3% 0.3%
LETG/HRC-S 0.02A 0.010A 0.010A
MEG/ACIS-S 0.03A (MEG) δ λ / λ = 1.0 x 10--4δ λ / λ = 1.0 x 10--4
HEG/ACIS-S 0.03A (MEG) δ λ / λ = 1.0 x 10--4δ λ / λ = 1.0 x 10--4
Absolute Effective Area ACIS 2% 5% 5%
HRC 7% 7% 7%
Absolute Effective Area
(1st order)		 LETG/HRC-S 10% 15% 10%
HETG/ACIS-S 10% 8%10%
Absolute Effective Area
(2nd - 7th Orders)		 LETG/HRC-S   20% 15%
HETG/ACIS-S   20%15%
Energy Resolution (FWHM) ACIS 3% 20 eV 20 eV
LETG/HRC-S 3% 20% 10%
MEG/ACIS-S 3% 3% 3%
HEG/ACIS-S 3% 3% 3%
Relative Efficiency (Effective Area) ACIS 1% on scales of 1' 1.0% 1.0%
ACIS   5% 3% on scales of 200 eV
HRC 1% on scales of 1' 0.7% 0.7%
LETG/HRC-S 3% on scales of 0.05A 6% 3%
HETG/ACIS-S 3% on scales of 0.05A 5% 3%
Point Spread Function HRC/ACIS 0.1% of peak within 1" annuli out to 16" 0.004% 0.004%
0.001% of peak between 16" and 20" 0.00008% 0.00008%
Relative Time Precision HRC 16 mu s 4-18 mu s 16 mu s
Absolute Time Accuracy HRC 100 mu s 35 mu s 35 mu s
ACIS-CC   1.5 m sec1.5 m s

Last modified:07/22/08


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