Low energy calibration with the Vela SNR
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Low energy calibration with the Vela SNR. EPIC Calibration & Operations Meeting. Mallorca, Spain, 2009 March 31 – April 1. Vela SNR: extended source with bright OVII emission.  excellent calibration source. 2001- 2007: 12 long FF observations,

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Low energy calibration with the Vela SNR

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Low energy calibration with the Vela SNR

EPIC Calibration & Operations Meeting

Mallorca, Spain, 2009 March 31 – April 1


Vela SNR: extended source with bright OVII emission

 excellent calibration source

2001- 2007: 12 long FF observations,

several with different pointing coordinates and roll angles

 fairly homogeneous illumination of the detector


Monitoring the absolute energy scale @ 0.57 keV with the Vela SNR:


Monitoring the absolute energy scale @ 1.49 keV with the internal calibration source:


Comparison: trends at 0.57 keV and 1.49 keV

Vela SNR

0.57 keV

internal calibration source

1.49 keV


Comparison: trends at 0.57 keV and 1.49 keV

0.574 keV (Vela SNR)

1.486 keV (Al-K, scaled)


Internal calibration source onboard XMM-Newton / EPIC-pn

Al-K Mn-K

inhomogeneous irradiation at Mn-K, illumination of quadrant 3 very poor


Superposition of all Vela SNR observations in FF mode

0.40 – 0.74 keV

photon map (singles)

exposure map

maximum: 172 singles/pixel

total exposure (after removing times of background flares): ~300 ks

exposure corrected map


Spatial properties of the absolute energy scale

0.40 – 0.74 keV

photon map

(singles)

 adaptive binning into subareas of similar signal


Spatial properties of the absolute energy scale

vertical binning according to response matrices

horizontal binning adaptively, criterion: ~5000 single events within 400 – 740 eV (above background)

 422 fields


Preparations for a joint fit

removal of periods of enhanced background

correction for local energy shifts due to errors in the offset map (epreject)

correction for energy shifts between the individual observations

correction for out-of-time events


Spectral model used ( E = 0.43 – 0.74 keV )

all line energies and widths coupled to reference line (O VII r)

relative line fluxes of O VII triplet fixed

continuum approximated by powerlow

8 fit parameters


Spectral model used ( E = 0.43 – 0.74 keV )


result:

energy scale spatially homogeneous within ±10 eV

however, also evidence for systematic shifts in a ring-like pattern


Checks for stability and reproducibility of the result

removal of periods of enhanced background

correction for local energy shifts due to errors in the offset map (epreject)

correction for energy shifts between the individual observations

correction for out-of-time events different binning, different spectral models


EPIC-Cal Meeting, Tübingen, Germany, 2003 Feb 3-5

1.186 keV (Ge-L)

9.874 keV (Ge-K)


EPIC-Cal Meeting, Tübingen, Germany, 2003 Feb 3-5

1.186 keV (Ge-L)

9.874 keV (Ge-K)


Printed Circuit Board


EPIC-Cal Meeting, Tübingen, Germany, 2003 Feb 3-5

1.186 keV (Ge-L)

9.874 keV (Ge-K)


EPIC-Cal Meeting, Tübingen, Germany, 2003 Feb 3-5


EPIC-Cal Meeting, VILSPA, Spain, 2004 Mar 23-24


EPIC-Cal Meeting, Mallorca, Spain, 2009 March 31 – April 1


Comparison with Mn-K


Comparison with Mn-K


Mn-K


EPIC-Cal Meeting, MPE-Garching, Germany, 2006 May 4

20 adu image, rev 546

Correcting spatial inhomogeneities of the absolute energy scale

  • offsets in the energy scale due to errors in the offset map

  • column gain variations after launch

  • CTI changes due to residual light through the ventilation hole


Correcting spatial inhomogeneities of the absolute energy scale

  • offsets in the energy scale due to errors in the offset map

  • column gain variations after launch

  • CTI changes due to residual light through the ventilation hole

EPIC-Cal Meeting, Mallorca, Spain, 2007 Nov 6-7


Correcting spatial inhomogeneities of the absolute energy scale

  • offsets in the energy scale due to errors in the offset map

  • column gain variations after launch

  • CTI changes due to residual light through the ventilation hole

EPIC-Cal Meeting, Mallorca, Spain, 2007 Nov 6-7


Correcting spatial inhomogeneities of the absolute energy scale

  • offsets in the energy scale due to errors in the offset map

  • column gain variations after launch

  • CTI changes due to residual light through the ventilation hole

EPIC-Cal Meeting, Mallorca, Spain, 2009 March 31 – April 1


Low energy calibration with the Vela SNR

EPIC Calibration & Operations Meeting

Mallorca, Spain, 2009 March 31 – April 1


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