Screening criteria for the XIS data in the version 2.0 processing
Screening of unfiltered XIS event files to create cleaned event files
has four steps, as shown in the processing log file
(aeNNNNNNNNN_joblog.html, which is in the "log"
subdirectory. "NNNNNNNNN" represents a sequence number of the
observation). The flow of the screening is as follows:
(1)Event selection based on the grade and pixel status
(2)Creation of Good Time Intervals (GTIs) in which some criteria are
simultaneously satisfied
(3)Event extraction with the GTI
(4)Rejection of hot/flickering pixels
Thus, we provide here screening criteria adopted in the version 2.0
processing, for users to screen the unfiltered event files. We
summarize the screening criteria below, followed by an example for
creating the cleaned event files using XSELECT.
A. Summary of the screening criteria
Selection criteria for each XIS event are summarized in Table 1. Each XIS event is classified by the ASCA grades on the basis of the 3x3 pixel patterns. This task is performed with "xispi", the XIS-specific tools. Grade 0, 2, 3, 4, and 6 are selected as X-ray events. Furthermore, a pixel status is given for each event by "xisputpixelquality". In the cleaned event files, bad CTE (Charge Transfer Efficiency) columns and the Spaced-row Charge Injection (SCI) and its adjacent rows are already removed by the status selection. The ASCA grade and pixel status are defined as "GRADE" and "STATUS" columns in the event files.
| Criterion | Parameter meaning | Responsible files |
|---|---|---|
| GRADE=0:0 2:4 6:6 | ASCA grades. Grade 0, 2, 3, 4, 6 are selected as X-ray events. |
aeNNNNNNNNNxi[0-3]_N_{5x5,3x3,2x2}[nb]MMMZ_uf.evt.gz (Unfiltered event file#) |
| STATUS=0:524287 or STATUS<2**19 |
Pixel status(*). Bad CTE columns are removed. For the observations with the SCI, the SCI and its preceding/trailing rows are also filtered out. |
(#)File name convention for the science data is described in the following URL: http://darts.isas.jaxa.jp/astro/suzaku/seq_v1data.html
Screening criteria to create the GTI file are given in Table 2. The listed items are related to the XIS 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. Fine tuning of the attitude is done when the star tracker (STT) locks reference stars. Thus, we remove the initial settling period using "ANG_DIST".
| Criterion | Parameter meaning | Responsible files |
|---|---|---|
| AOCU_HK_CNT3_NML_P==1 | Attitude is controlled in the pointing mode. Time intervals during maneuvers are removed. |
aeNNNNNNNNN.hk (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) |
| S[0-3]_DTRATE<3 | Telemetry bit rate (Super High : 0, High : 1, Medium : 2, Low : 3).
Since small amount of telemetry is allocated to X-ray events, the telemetry is easily saturated in the data rate "Low". Therefore, time intervals in this data rate are removed. |
aeNNNNNNNNNxi[0-3]_0.hk (XIS HK file) |
| SAA_HXD==0 && T_SAA_HXD>436 | Satellite is out of South Atlantic Anomaly (SAA).
Related parameters are defined as follows; SAA_HXD: Passage of SAA for the HXD. (0, outside, to 3: deep) T_SAA_HXD: Elapsed time after a SAA passage for the HXD. (in unit of seconds) |
aeNNNNNNNNN.ehk (Extended HK file) |
| ELV>5 && DYE_ELV>20 | Earth elevation angle and Day-earth elevation angle. (in unit of degrees) |
In the pipeline processing, the XIS data with some submodes for an editing mode is split based on the parameters in aeNNNNNNNNNxi[0-3]_0.hk (XIS HK file). The submode ID corresponds to "Z" in aeNNNNNNNNNxi[0-3]_0_{5x5,3x3,2x2}[nb]MMMZ_uf.evt.gz. However, most of the observations have only a single submode. Hence, the data split by the submode is usually unnecessary for users to reprocess the unfiltered event files. We show here the screening criteria applied to the "general" observations in Table 3. If you have the cleaned event files with some submode IDs and want to reprocess the data, please contact the Suzaku Help Desk (URL: http://cosmic.riken.jp/suzaku/help/index_e.html)
| Column | Extension name (No.) | Parameter meaning | Default value |
|---|---|---|---|
| For event thresholds: | |||
| S[0-3]_EVTHLW_[A-D] | XIS_EXPCND (5) | Lower limit of event threshold | 50 |
| S[0-3]_EVTHUP_[A-D] | Upper limit of event threshold | 3583 | |
| For area discriminator: | |||
| S[0-3]_AREA_DSC_[A-D] | XIS_EXP_MODEINF (6) | Area discriminator status. Enable: 1, Disable: 0 | 0 |
| S[0-3]_ADHST_[A-D] | XIS_EXPCND (5) | Horizontal start-pixel address for area discriminator | 0 |
| S[0-3]_ADHEND_[A-D] | Horizontal end-pixel address for area discriminator | 255 | |
| S[0-3]_ADVST_[A-D] | Vertical start-pixel address for area discriminator | 0 | |
| S[0-3]_ADVEND_[A-D] | Vertical end-pixel address for area discriminator | 1023 | |
| S[0-3]_DSC_INOUT_[A-D] | Target position to area discriminator. Outside: 1, Inside: 0 | 0 | |
| For grade discriminator(*): | |||
| S[0-3]_GRADE_DSC_[A-D] | XIS_EXP_MODEINF (6) | Grade discriminator status. Enable: 1, Disable: 0 | 0 |
| S[0-3]_GDSC_OTHERS | XIS_EXPCND (5) | Flag to output grade "Others" events to the telemetry (Out: 1, In: 0) | 0 |
| S[0-3]_GDSC_TRAIL_SP | Flag to output grade "Trailing split" events to the telemetry (Out: 1, In: 0) | 0 | |
| S[0-3]_GDSC_LEAD_SP | Flag to output grade "Leading split" events to the telemetry (Out: 1, In: 0) | 0 | |
| S[0-3]_GDSC_SINGLE | Flag to output grade "Single" events to the telemetry (Out: 1, In: 0) | 0 | |
The XIS team needs the trend data for the purpose of the XIS calibration. The trend data is also extracted in the pipeline processing and is open to the public. We summarize the substituted screening criteria to extract the trend data in Table 4.
| Substituted criteria | Products |
|---|---|
| 55Fe calibration source data: | |
| GRADE=0:0 2:4 6:6 | aeNNNNNNNNNxi[0-3]_0_{5x5,3x3,2x2}[nb]MMMZ_fe_evt.gz |
|
STATUS=65536:131071 196608:262143 327680:393215 458752:524287 or STATUS<2**19 && (STATUS%(2**17))>=2**16 |
|
| Day-earth event data: | |
| GRADE=0:0 2:4 6:6 | aeNNNNNNNNNxi[0-3]_0_{5x5,3x3,2x2}[nb]MMMZ_de_evt.gz |
| STATUS=0:524287 or STATUS<2**19 |
|
| SAA_HXD==0 && T_SAA_HXD>436 | |
| ELV<0 && NTE_ELV>0(*) | |
| Night-earth event data: | |
| GRADE=0:0 2:4 6:6 | aeNNNNNNNNNxi[0-3]_0_{5x5,3x3,2x2}[nb]MMMZ_ne_evt.gz |
| STATUS=0:524287 or STATUS<2**19 |
|
| SAA_HXD==0 && T_SAA_HXD>436 | |
| ELV<-5 && DYE_ELV>100 | |
B. Example of the screening
This is an example of the OBS_ID=101005010 observation, in which the SCI were not applied. The files used in the screening are as follows:
101005010/auxil/ae101005010.ehk.gz (Extended House Keeping file)
101005010/auxil/ae101005010.hk.gz (Common House Keeping file)
101005010/xis/event_uf/ae101005010xi[0-3]_0_3x3n000z_uf.evt.gz
(Unfiltered event files)
101005010/xis/hk/ae101005010xi[0-3]_0.hk.gz
(XIS House Keeping files)
1. Screen with xselect (filter column), using GRADE and STATUS information.
unix% xselect xsel:SUZAKU > set datadir . xsel:SUZAKU > read event ae101005010xi0_0_3x3n000z_uf.evt.gz xsel:SUZAKU-XIS0-STANDARD > filter column "GRADE=0:0 2:4 6:6 STATUS=0:524287" or xsel:SUZAKU-XIS0-STANDARD > select event "(GRADE==0||GRADE==2||GRADE==3||GRADE==4||GRADE==6)&&(STATUS<2**19)"
Calibration source areas are not removed in the pipeline processing. You are requested to do by yourself if needed. Substitute for the above command as follows;
xsel:SUZAKU-XIS0-STANDARD > filter column "GRADE=0:0 2:4 6:6 STATUS=0:65535 131072:196607 262144:327679 393216:458751" or xsel:SUZAKU-XIS0-STANDARD > select event "(GRADE==0||GRADE==2||GRADE==3||GRADE==4||GRADE==6)&&(STATUS<2**19&&(STATUS%(2**17))<2**16)"(The line breaks between the commands and the criteria above have been inserted for disply purposes only.)
2. Screen with xselect (select hk), using common HK, to discard the data during maneuver.
xsel:SUZAKU-XIS0-STANDARD > read hk hkfiles=ae101005010.hk.gz expand=yes > HK file directory >[./] xsel:SUZAKU-XIS0-STANDARD > select hk "AOCU_HK_CNT3_NML_P==1" xsel:SUZAKU-XIS0-STANDARD > extract event xsel:SUZAKU-XIS0-STANDARD > save event ae101005010xi0_0_3x3n000z_uf.evt_gsmnvcut > Use filtered events as input data file ? >[no] yes
The common HK file is in "auxil" subdirectory.
3. Screen with xselect (select hk), using XIS HK, to discard the data during data rate low. The criteria are given by "Sn_DTRATE < 3", where n=0, 1, 2, 3, depending on the sensor ID.
xsel:SUZAKU-XIS0-STANDARD > read hk hkfiles=ae101005010xi0_0.hk.gz expand=yes > HK file directory >[./] xsel:SUZAKU-XIS0-STANDARD > select hk "S0_DTRATE<3" xsel:SUZAKU-XIS0-STANDARD > extract event xsel:SUZAKU-XIS0-STANDARD > save event ae101005010xi0_0_3x3n000z_uf.evt_dtratecut > Use filtered events as input data file ? >[no] yes
4. Screen with xselect (select hk), using extended house keeping (EHK) file, to discard the data during SAA. Time intervals with large offset angles to the pointing position are also removed.
xsel:SUZAKU-XIS0-STANDARD > read hk hkfiles=ae101005010.ehk.gz expand=yes > HK file directory >[./] xsel:SUZAKU-XIS0-STANDARD > select hk "SAA_HXD==0 && T_SAA_HXD>436 && ANG_DIST<1.5" xsel:SUZAKU-XIS0-STANDARD > extract event xsel:SUZAKU-XIS0-STANDARD > save event ae101005010xi0_0_3x3n000z_uf.evt_saacut > Use filtered events as input data file ? >[no] yes
The EHK file is in "auxil" subdirectory.
5. Then, cleaned events are selected with the following criteria:
xsel:SUZAKU-XIS0-STANDARD > read hk hkfiles=ae101005010.ehk.gz expand=yes > HK file directory >[./] xsel:SUZAKU-XIS0-STANDARD > select hk "ELV>5 && DYE_ELV>20" xsel:SUZAKU-XIS0-STANDARD > extract event xsel:SUZAKU-XIS0-STANDARD > save event ae101005010xi0_0_3x3n000z_uf.evt_elvcut > Use filtered events as input data file ? >[no] no xsel:SUZAKU-XIS0-STANDARD > exit > Save this session? >[no]
6. Finally, "cleansis" is applied to remove hot/flickering pixels.
unix% cleansis datafile=ae101005010xi0_0_3x3n000z_uf.evt_elvcut \
outfile=ae101005010xi0_0_3x3n000a_cl.evt \
cellsize=5 logprob=-.53E+01 bthresh=3 \
phamin=0 phamax=4095 \
chipcol=SEGMENT
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