Question ID = 0152
Question ID = 0152
Assigned Member (担当者)2012-01-19, M.NakajimaName and Institute (質問者/機関)Yang HuanUniversity of Science and Technology of China (Graduated student, first year) Question (質問)The question is about the calibration uncertainty of XIS at energy <1 kev.We extracted spectra of Mrk 352 using the latest calibration, and fit the XIS and PIN spectra simultaneously. The spectra <1 kev seem to have large uncertainty. And XIS0 spectra at energy <1 kev are not consistent with XIS3. We find that a "pcfabs" component is needed in the best fit model, but this is very sensitive to the soft band spectra. We hope to make sure that if the need of this component is due to the <1 kev uncertainty. From the "Suzaku Memo", the effective area of XRT response at energy <1 kev are not well calibrated. How can we deal with these uncertainty? Are there some compromised way, for example, drop the XIS0 and XIS3 spectra below 1kev, only use XIS1? Answer from(回答の文責)Takayuki TamuraAnswer (答え)Your question was answered by an expert on the XIS from the XIS help team as given below.
from here -------------------------- All the sensors suffer the same problem in a different degree and the calibration uncertainty is different among the sensors. Users need to make a judgement which senrors to use in what energy band based on their scientific goals.
For conpromise, you can adjust the contamination model by yourself. The
model includes the H, C, N, and O column densities as a function of
time for each sensor. You can refer to the closest calibration
observations of PKS2155-304 and RXJ1856.5-3754 to guess the values of
these free parameters. For a detailed procedure, contact the XIS help
at xishelp AT astro.isas.jaxa.jp. You can also check the following pages and papers on the calibration in general.
Status （詳細なステータス）2012-01-19 Accept2012-01-26 Answered 2012-02-06 Done 
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