> Data Process
Processing Version 18.104.22.168/4/5
Last Updated on 2006 December 19
Suzaku data are available from DARTS.
22.214.171.124 is a major update for HXD and a minor update for XIS from
version 126.96.36.199. 188.8.131.52/5 is a update of XIS micorcode CALDB, which is
needed to process XIS data carried out with new onboard microcode, and
the products' quality is the same as that of 184.108.40.206. Users of
previous version data are recommended to download 220.127.116.11/4/5. Old
versions are summarized in the history page.
- XIS files:
- Timing mode data are not processed.
- Dead time is not calculated when the burst mode option is used.
- Some of the events might have invalid PI values (PI=4095), when
the burst and window options are combined. These events are
effectively removed from the subsequent analysis, resulting in a
slight reduction in normalization. See Suzaku Memo 2006-20 for details.
- Details of the limitations associated in the data processing
are summarized in Suzaku Memo 2006-16.
- The XIS team is preparing background database and tools to be
used by Guest Observers for extended source analysis. The temporal
version which covers from 2005 September to 2006 May is available at
XIS data analysis page.
- HXD files:
- GSO data in this release are processed by use of the temporary
gain correction file which is automatically created in the pipe-line
processing, and hence the systematic uncertainty is rather large. This
sometimes causes improper data screening and the resultant cleaned
event files are wrong or even non-existent. To obtain more precise
gain correction, including the short-term gain variation, observers
must perform a re-processing with the latest CALDB file by themselves.
The detailed procedures are explained here and other manuals.
- The accuracy of non-X-ray background (NXB) model is crucial to
precisely obtain scientific results, for a non-imaging hard X-ray
instrument like HXD. The HXD team has been investigating spectral and
temporal behaviors of in-orbit detector background. A "background
estimator" tool will be released as a part of HEADAS package in
future, but it is still under development. Until the tool is released,
the latest results of the NXB modeling are distributed as "background
event files" from the Suzaku
Web page, with 2-4 weeks or 4-6 weeks delay from the data
processing for PIN or GSO data, respectively. The detail is caused by
the fact that we need the actual hk data to produce it, and also we
need to reprocess the GSO data with improved gain determination. At
present, the background subtraction is accurate typically at 5% level,
but observers are strongly recommended to check the model validity
with a comparison between light-curves of data and background
model. Details of the modeling will be described in a series of
documents (reproducibility of PIN background: Suzaku Memo
2006-42, others under preparation).
- Since the dead-time of HXD data is order 4-7% even for
background-dominated sources, users should correct it by use of the
`hxddtcor' FTOOL. On the other hand, the background event files of the
PIN are already dead-time corrected. Those for the GSO in NOT dead
time corrected. See documents such as "7-steps" for detail.
- Data obtained from 23 March 2006 to 13 May 2006 sometimes suffer
additional dead time, clearly seen as dips in raw (i.e. not dead-time
corrected) light curve. This is caused by the data transfer saturation
within the HXD electronics. The GSO LD was set at a bit lower during
these days. The dips are seen in short periods with high data-rates,
e.g. after the SAA and/or in low COR. In principle, 'hxddtcor' can
handle this phenomena and the spectra shall not be affected. Since the
issue is yet to be calibrated, it is better to check if there is a
difference in spectra including and excluding these periods. The
phenomena may also take place even if your data is not within the
specified days. The HXD team is now investigating the recent trends.
- Common issues:
- Before guide stars are available for the first time (initial 90 minutes or less), both attitude control and ground attitude determination could be less accurate. Users should check images and light curves carefully.
- There is a time-dependent misalignment of 30-60 arcsec, which
is synchronized with the orbital period of the satellite (96
min). This is not incorporated to calculate X/Y in this version. A
correction tool is under development.
- Spectral Analyis:
- ARF builder using ray-tracing (`xissimarfgen') is available
2006-39), while RMF generator is not included in this
release. Standard RMF and ARF files can be obtained from CALDB page. These ARF files are limited to
point source files for standard pointing positions.
- These standard responses do not include the XIS contamination,
which is time, position, and sensor dependent. Please introduce
additional absorption model with appropriate column densities for C
and O in the case of point source analysis, or use `xissimarfgen' in
general. Users can calculate the required C column (C/O=6 in number
ratio is assumed at present) with `xiscontamicalc'. For further
details on the contamination, see the Technical Description (will be
released early 2006 October).
- The calibraton of the energy scale is underway. XIS gain is
accurate to +-0.2% in the iron band and +-5 eV below 1 keV.
- Effect of the radiation damage is under study now. In
addition, inprecise correction for spatially dependent charge transfer
inefficienty (CTI) results in line broadening of order 50 eV (in
sigma) at Fe K, and a degradation of quantum detection efficiency of
about 5% (as of 2006 April).
- XIS calibration accuracy becomes worse in window mode or in
- Artificial structure is present in the XIS spectrum in 500-504
ch (1.825-1.84325 keV), which should be discarded from the analysis.
- Local structures may be present in the XIS spectrum with a
level of +-10% in 2-8 keV.
- The energy response matrices of HXD-PIN have been verified
with the Crab observations, for both of the XIS-nominal and
HXD-nominal positions. Results are shown in figures. In case of observations
performed before 2006 May 24, discrepancies between the data and model
are smaller than a few percent in the energy range of 12-40 keV, while
they become larger than 3% at >20 keV after the change of one of
four PIN-Si bias voltages on 2006 May 29. A newer version of PIN
energy response is under development.
- Users should allow 13% uncertainties at the XIS nominal
position and 15% uncertainties at the HXD nominal position in
HXD/PIN-XIS cross-normalization. For further details, see Suzaku Memo 2006-40.
- Timing Analysis:
- XIS event times are quantized to 8s (see above). Their
absolute accuracy is not calibrated yet.
- HXD event times have 61 microsec resolution. Absolute timing
accuracy is not yet calibrated to this resolution.
- Barycentric correction software `aebarycen' is
released. Calibration using this tool is underway.
- Imaging Analysis:
- Exposure map software is not yet included.
Calibration files and related files can be obtained from the Suzaku
page in ISAS
ISAS/JAXA Department of High Energy Astrophysics
Last Modified: Tuesday, 19-Dec-2006 21:10:56 JST