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The "why" topics are a second layer to the threads; they provide supplemental information for the user that is interested in digging deeper. Some of the topics highlight common pitfalls and subtleties in the CIAO software, others describe aspects of the Chandra Observatory and data obtained with it. The documents also provide information on why certain science decisions are made, enabling the user to tailor the analysis to a particular dataset.

Please email the Helpdesk if you have suggestions for topics that you would like to see discussed here.

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Data Products

• The Aspect Solution & pcad_asol1.fits Files
• Dither
• Multi-OBI Observations

ACIS: Data Processing

• CTI Correction
• Time-dependent Gain
• PHA Randomization
• Pixel Randomization
• Very-faint Background Cleaning
• Dead Area Correction
• QE Contamination
• Destreaking ACIS Data

ACIS: Analysis

• -110 C Observations
• Cosmic-Ray Afterglows
• Continuous Clocking Mode
• Choosing an Energy Filter
• Creating ACIS RMFs with mkacisrmf

HRC: Data Processing

• HRC-I Gain Maps
• HRC-S Time-dependent Gain Corrections and PI Filter
• Degap
• AMP_SF Correction

HRC: Analysis

• HRC-S QE/QEU
• HRC-I RMF

Pileup

• An Overview of Pileup
• When and How to Avoid Pileup (or not!)

Miscellaneous

• Timing Analysis with Lightcurves (ACIS & HRC)
• HRMA Effective Area
• HETG Grating Efficiency