SAG+SASWG Meeting Potsdam 2006-11-14/15

SAG+SASWG Meeting Potsdam 2006-11-14/15

PN Tasks – Status Report (update since Leicester)

Hermann Brunner - MPE

epframes: The dark quadrant problem

in small number of observations event time vector stops while exposure vector continues => one or several `dark´ image quadrants not correctly represented in exposure maps

machine-dependent: ok on Tru64 (32/64 bit issue ?)

workarounds: - keyword OBT_WARN to identify affected exposures (InvalidObtValue warning) - task parameter withallobtgti to adjust GTI to make images and exposure maps consistent - check for NaNs in „all good AUX1 entries“ loop


do i = 1, ngaux1-1

if (aux1Gtime(i) .EQ. aux1Gttime(i) ) then

...

consistency with hardware where the problem did not occure ??

task uploads should be made by the task author or with the consent of the task author

Question on version numbers

patch level uploads should not contain interface changes for DEPEND mechanism to work (?)

(counter-)example: oal 3.114.1 -> oal 3.114.2 new feature: OAL_hasconfIPPV( )


merge:now merges both STDGTI and GTI to permit merging of individual flare screened event sets

permit merging of arbitrary numbers of event files (current version merges two event files)

CAUTION: merged event files don‘t work with all SAS tasks !

epatplot: missing axis labels on some arcitectures but not on others (different pgplot libraries ? – ongoing analysis)

epchain: corrected error when running epchain for specific exposures in odfacess=oal mode (SPR closed)


epreject - ongoing activities: - define new pn event flags

BELOW_THRESH flag bit 26 LOEN_NOISE flag bit 27

and include in EPN_REJECTION_MASK

purpose: - exclude events shifted below threshold from pattern recognition (BELOW_THRESH) - replacement for NOISE column (LOEN_NOISE)

discussed with CG – SCR to ssclib issued

- replace noise screening method with different method

current method: noise properties derived from calclosed obervations

- problems: may cause discontinuities in soft spectrum

of weak sources

new method: remove noisy frames (more than one event

per frame below 31 ADU)

and perform statistical noise flagging based on

observation itself (calclosed noise-maps not

needed anymore)

- problem: spectral analysis – interface to arfgen

new event table extension:

noise ratio image/vector ??


23.2 ks closed FF 0 50 0 3

application of the original method (implemented in the SAS task epreject)

Konrad Dennerl, EPIC Cal meeting, Mallorca, ct. 2006

EPIC-pn detector noise (LW)

20 50 adu

99% suppressio

n

Original method (“method 1”):

Suppression of events below 50 adu according to a reference noise

distribution deduced from long calclosed

exposures

Shown in blue is the result of this method applied to a (long)

calclosed exposure, to illustrate the effect on

a very faint X-ray source

SNR 1E 0102, rev 803, LW, thick, 30 ks

= +

singles, 20 – 30 adu, all frames

singles, 20 – 30 adu, frames with more

than 1 event below 31 adu per frame and

CCD

singles, 20 – 30 adu, frames with 1

event below 31 adu per frame and

CCD

number of frames removed

original number of

frames

percentage of frames removed

removing frames with more than 1 event below 31 adu per CCD and frame:


singles, 0.3-3.0 keV

mask for source regions to be avoided for noise

determination

source region mask


In order to determine the noise properties, some areas have to be ignored:

common fit (for all CCDs) between 40 and 100 adu

Deriving the general properties of the detector noise from closed exposures

SNR 1E 0102, rev 803, LW, thick, 30 ks, source regions included

red: data set to be corrected, blue: closed exposure

average 45-55 adu flux

SNR 1E 0102, rev 803, LW, thick, 30 ks, source regions excluded

extrapolated flux at 20 adu averaged between all CCDs


spectrum before/after noise suppression, source regions

excluded


unfiltered data singles, 25 adu after noisy frame removal



after noisy frame removal singles, 25 adu after spatially uniform noise suppression


after noisy frame removal singles, 25 adu after spatially variable noise suppression

unfiltered data singles, 30 adu after noisy frame removal


after spatially uniform noise suppression singles, 30 adu after spatially variable noise suppression



singles, 100-130 eV

original dataafter noisy frame

removal and spatially uniform noise suppression

after noisy frame removal and spatially

variable noise suppression


singles, 130-140 eV






singles, 140-150 eV






singles, 150-200 eV






singles, 200-300 eV





Todo list:

epreject: new treatment of noise screening, possibly split in separate tasks for offset correction and noise screeing

epframes/epevents: internal interface change after solution of OAL time jump problem epexposure: randomisation of event times (after solution of OAL time jump problem)

calpnalgo: implement/calibrate mode dependent temperature gain corrections – may require calpnalgo/CCF changes

SSC Consortium Meeting Potsdam 2006-11-14

SAG+SASWG Meeting Potsdam 2006-11-14/15

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