Subpixel Event Repositioning (SER) Algorithms
for Chandra/ACIS Imaging (V1)
Subpixel Event Repositioning (SER) techniques have been demonstrated to
significantly improve the already unprecedented spatial resolution of Chandra
X-ray imaging with the Advanced CCD Imaging Spectrometer (ACIS). Chandra
CCD SER techniques are based on the premise that the impact position of events
can be refined, based on the distribution of charge among affected CCD pixels.
ACIS SER models proposed thus far are restricted to corner split (3- and
4-pixel) events, and assume that such events take place at the split pixel
corners. The modified SER techniques available below use two-pixel splits
as well, and incorporate more realistic estimates of photon impact positions,
according to results described in Li et al ( 2003, ApJ and 2004 (Aug), ApJ). These modifications were developed
in Chester F. Carlson Center for Imaging
Science at RIT, under the guidance of
prof. Joel H. Kastner,
with the helps from PSU and MIT faculty members.
poster2 (pdf file (8.7MB), PS file (13 MB)) -- Static SER method
and its applications.
2. ApJ paper1 (Tsunemi et al. 2001) -- Tsunemi
et al. (2001) method, i.e., static method restricted to corner split events
3. ApJ paper2 (pdf)(Li
et al. 2003) -- Energy dependent SER method for BI CCDs.
4. Manuscript (pdf) (Li et al. 2004, ApJ) --
Charge Split dependent SER, static, energy-dep. SER for both BI and FI CCDs.
2. Implementation Steps
3. IDL Codes
-- For level 1 event list, following the CIAO steps and remove
randomization applied by standard ACIS processes.
- Event Relocation -- Apply IDL program SER.PRO,
following the usage specification. NOTE: The code hasn't been completely
tested. Please let me know if you have any error messages.
- Result Comparison -- The spatial resolution improvement is strongly
dependent on your source spectra, employed CCD type (FI or BI), and source
4. What do you need to do
- Download SER.PRO with other external functions here.
- You need have the IDL programs in ASTROLIB too. Please download
5. Download SER package
- Make CIAO
installed in your system, the latest version is 3.0 now (for unrandomization).
- Some IDL programs in ASTROLIB was impicitly
used. Download and make them avaliable under your IDL path.
- SER.PRO and other external functions, as well as the necessary data
set (they are within a package). Unpack the package
and put all the files in same directory.
6. An example ( will be available soon)
- SER package, including the IDL codes and
- Unpack the package, by typing [tar -xvf ser.tar]
- Refer to the comments, especially the keyword usages, in SER.PRO
for further information
7. SER on HETG data
Problems? Comments? Please contact Dylan:
You also can contact Prof.
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