ACIS Anomaly Documentation

These pages detail possible ACIS-related anomalies that may occur. Each page describes the anomaly itself, when it has happened in the past, how likely it is to happen again, and what the response should be. Appropriate links are also given to relevant flight notes, procedures, and other documentation.

Contents:

• DPA-A Anomalous Shutdown (BEP-A Active) (Last Updated April 27, 2026)

• DPA-B Anomalous Shutdown (BEP-A Active) (Last Updated April 27, 2026)

• DPA-A Anomalous Shutdown (BEP-B Active)

• DPA-B Anomalous Shutdown (BEP-B Active)

• DEA-A Anomalous Shutdown (Last Updated May 7,2024)

• DEA Sequencer Reset During a Science Observation (Last Updated September 11, 2018)

• FEP Anomalous Reset (Last Updated April 27, 2026)

• Hi/Lo Pixel Anomaly (Last Updated June 28, 2017)

• Trickle Bias / T-Plane Latchup Anomaly (Last Updated August 29, 2022)

• FEP Thresholder Anomaly (Last updated August 14, 2017)

• ACIS Door Mechanism side B Anomalous Enable (Last updated April 27, 2026)

• ACIS Science Run Termination Failure Anomaly (Last updated August 29, 2022)

• BEP Bus Crash Anomaly (Last updated April 27, 2026)

HOWTO: Editing ACIS Anomaly Pages