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Last modified: 26 October 2016

URL: http://cxc.harvard.edu/ciao/bugs/hrc_process_events.html

Bugs: hrc_process_events


Table of Contents

Caveats


Caveats

# hrc_process_events (CIAO): The following error occurred 2482 times:
  dsHPEEVENTSEQERR -- WARNING: Out of sequence events discovered in hrc_evt1.fits.

There are occasional events that appear in the telemetry stream with time tags that make them seem to have occurred out-of-sequence. One special case where this occurs has been documented (see the Out-of-sequence HRC Time Tags memo); other occurrences are most likely to be caused by hiccups in the HRC or by double-bit errors in telemetry (single-bit errors are corrected).

This warning may be ignored in most cases, as long as the number of events flagged as out-of-sequence is a small fraction of the total number of events in the file. For example:

unix% dmlist hrc_evt1.fits blocks
 
--------------------------------------------------------------------------------
Dataset: hrc_evt1.fits blocks
--------------------------------------------------------------------------------
 
     Block Name                          Type         Dimensions
--------------------------------------------------------------------------------
Block    1: PRIMARY                        Null        
Block    2: EVENTS                         Table        20 cols x 798768   rows
Block    3: GTI                            Table         2 cols x 7        rows

(2482.0 / 798768.0) * 100 = 0.310729

Since there are 798768 events in the file, the 2482 that were flagged as out-of-sequence make up just 0.31% of the total events.

# hrc_process_events (CIAO): The following error occurred 224 times:
  WARNING: can't find a proper degap value for this raw coord. in hrc_evt1.fits.

The warning means that the new degap lookup table does not have a matched value for the given raw coordinate which most likely is out of the boundary. Events with such warning will be indicated as bad in the output status column.

This warning may be ignored in most cases, as long as the number of events flagged as out-of-sequence is a small fraction of the total number of events in the file. For example:

unix% dmlist hrc_evt1.fits blocks
 
--------------------------------------------------------------------------------
Dataset: hrc_evt1.fits blocks
--------------------------------------------------------------------------------
 
     Block Name                          Type         Dimensions
--------------------------------------------------------------------------------
Block    1: PRIMARY                        Null        
Block    2: EVENTS                         Table        20 cols x 798768   rows
Block    3: GTI                            Table         2 cols x 7        rows

(224.0 / 798768.0) * 100 = 0.0280432

Since there are 798768 events in the file, the 224 that were flagged as out-of-sequence make up just 0.03% of the total events.


Last modified: 26 October 2016
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