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Screening criteria for the HXD data in the version 2.0 processing

2007-08-10 by the HXD team

Screening of unfiltered HXD event files to create cleaned event files has two steps, as shown in the processing log file (aeNNNNNNNNN_joblog.html, which is in the "log" subdirectory).
(1)Event selection based on the event grade
(2)Event extraction with the Good Time Intervals (GTIs), in which several criteria are simultaneously satisfied.
Below we provide the screening criteria adopted in the version 2.0 processing, for users to screen the unfiltered event files by themselves.

Summary of the screening criteria

Selection criteria for each HXD event are summarized in Table 1.

Table 1: Event grade of the HXD
Detector Criterion
GSO DET_TYPE=0 DET_TYPE is determined from GRADE_xxxx columns assigned by the hxdgrade, based on the pulse height, trigger, and hitpattern information of each event. Detailed meanings of GRADE_xxxx are described in the help file of hxdgrade.
pseudo DET_TYPE=2

Screening criteria to create the GTI file are given in Table 2. The listed items are related to the HXD data rate, the SAA passages, the satellite attitude, and the satellite position in orbit. The attitude sometimes has an offset of a few arcmin to the pointing position, just after the maneuver.

Table 2: Screening criteria to create Good Time Intervals (GTIs)
Criterion Parameter meaning Responsible files
AOCU_HK_CNT3_NML_P==1 Attitude is controlled in the pointing mode. Time intervals during maneuvers are removed.
(common HK file)
ANG_DIST<1.5 Distance from the mean pointing position. (in unit of arcmin) The initial settling period after the maneuver is removed. aeNNNNNNNNN.ehk
(Extended HK file)
HXD_DTRATE<3 (GSO only) Telemetry bit rate (Super High : 0, High : 1, Medium : 2, Low : 3).
Only a portion of GSO data are output to the telemetry during the data rate "Low".
(HXD HK file)
HXD_HV_W0_CAL>700 && HXD_HV_W1_CAL>700 && HXD_HV_W2_CAL>700 && HXD_HV_W3_CAL>700 &&
HXD_HV_T0_CAL>700 && HXD_HV_T1_CAL>700 && HXD_HV_T2_CAL>700 && HXD_HV_T3_CAL>700
High voltages from eight HV units are reduced to zero during the SAA passage to avoid the radiation damage of photo-multiplier tubes.
SAA_HXD==0 && T_SAA_HXD>500 && TN_SAA_HXD>180 && COR>6 SAA_HXD: Satellite is out of South Atlantic Anomaly (SAA). (0->3: deep)
T_SAA_HXD: Elapsed time after a SAA passage for the HXD. (in unit of seconds)
TN_SAA_HXD: Time to the next SAA passage (seconds).
COR: Cut-Off Rigidity (GV).
(Extended HK file)
ELV>5 Earth elevation angle.
(in unit of degrees)
Telemetry is not saturated GTI file created by hxdgtigen will be "AND"-ed to above criteria aeNNNNNNNNNhxd_0_tlm.gti

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This file was last modified on Tuesday, 24-Mar-2009 18:50:17 EDT

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