Data Caveats

This page contains warnings concerning the quality of data products in the Chandra Archive, grouped by instrument. For a more detailed description of the data products, visit the Data Products Guide.

All data received from the Chandra X-ray Observatory is processed through the standard data processing (SDP) pipelines at the Chandra X-ray Center. CIAO is designed for use with data with a processing version of "R4CU5UPD8" or "DS6.0.0" or higher; see the Note on Processing Versions for more information. To obtain the most up-to-date processing for a given observation, visit the Chandra Data Archive.

If you have any specific questions about your data, please email the Helpdesk.

General

The current Calibration Status Report

For data processed prior to DS6.9 (released August 2002) see this off-axis angle caveat

ACIS

• ACIS Pipeline-Processed Event Data
• ACIS Pipeline-Processed Mask Files
• Spectral analyses of ACIS data with a limited pulse-height range (11 May 2009)
  This document replaces an earlier caveat titled "ACIS Event Thresholds".
• ACIS Onboard Event Filtering
• Degredation of Low Energy QE
• Clarification of time-related keywords in FITS header
• Time Keywords in Interleaved Data
• Zero-exposure Event File
• Incorrect Data Products for Jupiter (ObsIDs 2398,2399,2400,2401,2407,2408)

HRC

• LETG+HRC-S Dispersion Relation
• HRC-S Focus Position Change on 6 November 1999
• Out of Sequence Events
• Timing Anomalies
• Time Gaps in HRC Data

Gratings

• Effective Area Calibration

Detect

• Use of PSF in Detection

Aspect

• Aspect Caveats
• Chandra Astrometric Accuracy

Timing

• Accuracy of Predicted Ephemeris

Responses

• PSF Library
• Effective Area Calibration