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Details of HRC Instrument Settings Changes

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HRC Command Event Width Threshhold

10/05/00 - HRC Command Event Width Threshhold

The default value of the commanded event-width threshold was changed for both the HRC-I and HRC-S from 3 to 2 at 2000:279:12:57. This change occurred between two HRC observations - ObsIDs 1857 and 1853.

The change was made so that two of the bits in the event status word could be used to help unambiguously identify those events that require a correction to the telemetered crossed-grid charge detector signals in order to reduce image blurring. A future version of the CIAO tool hrc_process_events will use these bits. The original event-width threshold was chosen to flag events that were likely to be due to charged particles but other screening tests performed on the events provide this flagging.

Effective with the instrument configuration change, a change was made to the standard level 2 processing pipeline. The event status bit mask used to filter when making the level 2 event-list was modified so ignore the state of the two relevant bits in the event-status word; this change was effective in software version R4CU5UPD11.1. Users should be cautioned not to use the bit-mask defined in earlier versions of the software on HRC data taken after 2000:279:12:57.

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Last modified: 09/25/12

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