SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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The XMM-The XMM-NewtonNewton Slew Survey: Slew Survey: processing challengesprocessing challenges
Richard SaxtonRichard Saxton11,,Bruno AltieriBruno Altieri11, Diego Bermejo, Diego Bermejo44, , M. Pilar EsquejM. Pilar Esquej1,41,4, Michael Freyberg, Michael Freyberg33, Veronica , Veronica LazaroLazaro44, Andy Read, Andy Read22
11 ESAC, ESA, Spain ESAC, ESA, Spain22 University of Leicester, U.K. University of Leicester, U.K.33 MPE, Garching, Germany MPE, Garching, Germany44 Universidad Complutense de Madrid, Spain Universidad Complutense de Madrid, Spain
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Talk outlineTalk outline
Survey characteristicsSurvey characteristics ProcessingProcessing Attitude reconstruction: Astrometry Attitude reconstruction: Astrometry (1)(1) Spurious sourcesSpurious sources
• Optical loading Optical loading (2)(2)• Detector flashes Detector flashes (3)(3)
SensitivitySensitivity Extended sourcesExtended sources
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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XMM-XMM-NewtonNewton 3 mirror modules 3 mirror modules
with 58 shells with 58 shells eacheach
EPIC:EPIC:• 2 MOS CCD 2 MOS CCD
camerascameras• 1 pn CCD 1 pn CCD
cameracamera
2 Reflecting 2 Reflecting Grating Grating SpectrometersSpectrometers
1 Optical Monitor1 Optical Monitor
Mirrors
RGS-Camera 1 RGS-Camera 2
EPIC-MOS-Camera 2 EPIC-MOS-Camera 1
EPIC-pn-Camera Optical Monitor
RGS
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Survey Survey CharacteristicsCharacteristics
Average slew length : 86 degrees
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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OverviewOverview- 465 slew datasets in archive (since Rev 314, end-2001)- 465 slew datasets in archive (since Rev 314, end-2001)- PN, MOS-1/2 exposures in Medium filter with the observing mode set - PN, MOS-1/2 exposures in Medium filter with the observing mode set
to that of previous pointed observationto that of previous pointed observation- Data initially available for slews longer than 30 minutes duration- Data initially available for slews longer than 30 minutes duration- Open-slew speed = 90 degrees / hour, i.e. on-source time ~14 secs- Open-slew speed = 90 degrees / hour, i.e. on-source time ~14 secs- Area covered to date ~8000 deg- Area covered to date ~8000 deg2 2 (~20% of sky)(~20% of sky)
ecliptic coordinates
great circles passing through ecliptic poles due to sun constraint.
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Processing strategyProcessing strategy
• Tangential projection not valid over whole slew. Divide slew into 1 deg2 images and recalculate sky positions.
• Source search using near-standard pipeline eboxdetect/emldetect combination tuned for ~zero background.
• Use sources with DET_ML > 10 equivalent to 3.9 sigma
• Search independently in three bands and produce three catalogues :
soft (0.2-2 keV) hard (2-12 keV) total (0.2-12 keV)
Dedicated pipeline MPE/ESAC/LUX with database at ESAC
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Initial impressionsInitial impressions
Source extended into a 4 arcmin streak due to 2.6 second frame time
Full frame (73ms) mode streak = 6 arcsecs – not noticeable
Extra pn sensitivity + additional MOS background means little to be gained from analysing MOS slews
Epic-pn attitude reconstruction good
MOS PN PN (eFF)
Extended full frame streak of 18 arcsecs
Slew direction
We can process slew data with a small s/w change (available in SAS 6.5)
New operations strategy (from end of 2004):New operations strategy (from end of 2004):
MOS slews will be used for calibrationMOS slews will be used for calibration All PN slews longer than 15 mins will be down-linked and All PN slews longer than 15 mins will be down-linked and
processed and used for scienceprocessed and used for science Medium filter if FF,EFF,LW and Closed for other modesMedium filter if FF,EFF,LW and Closed for other modes
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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EPIC-pn source characteristicsEPIC-pn source characteristicsSource Count Distribution Exposure Time Distribution
Minimum @ 4 counts Maximum @ ~ 10 secondsMean 6.3
- Can calculate flux limits for the XMM slew survey
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Current StatusCurrent Status (15/07/2005)
20052005 20102010 20152015
Equivalent Equivalent fraction of fraction of sky coveredsky covered
20 %20 %
(25)*(25)* 50%50%
(60)(60)80%80%
(100)(100)
Number of Number of sourcessources
40004000
(5000)(5000)1000010000
(12000)(12000)1600016000
(20000)(20000)
Completeness
* Including high background slews
• Initial processing of 374 slews (297 are FF, eFF or LW) – 25% have high background
• Images created and source searched for 138 slews giving
1596 sources in total band1596 sources in total band1231 sources in soft (0.2-2.0 keV) 1231 sources in soft (0.2-2.0 keV) bandband221 sources in hard (2.0-12.0 221 sources in hard (2.0-12.0 keV) bandkeV) band
At faint end, 169 soft-band andAt faint end, 169 soft-band and61 hard-band sources, not 61 hard-band sources, not detected in the total banddetected in the total band
Source density: Source density: ~0.5 sources ~0.5 sources per square degreeper square degree
• 60% have RASS counterpart
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Astrometry: initial comparisonAstrometry: initial comparison
Comparison with ROSAT survey positions shows a wide distribution, with a tail up to 1 arcmin
median=31” offset
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Attitude Problem: correctionAttitude Problem: correction
Two types of positional error
(1) Real error of ~10″
(2) Error of 0-60″ (mean 30″) but only in slew direction
Slew direction
AB Dor
‘Error ellipse’ around source (slew-oriented)
Good relative astrometry: ~10 arcsec, but poor absolute astrometry: ~30 arcsec
Systematic shift was evidenced, traced to :• quantisation of time to 1 second in AHF • timing error in the RAF, due to a delay of 0.75s of the star tracker CCDs leading to a systematic offset
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Achieved astrometric accuracyAchieved astrometric accuracy
RASS : 16” Simbad : 8”
Close to the theroretical limit !
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Optical Loading – A Problem?Optical Loading – A Problem?
Contrary to pointed observations, no offset maps is computed/applicable.
Possibility of optical loading contamination
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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UY VirUY VirDSS Image 2’×2’ Total band (0.2-12 keV)
Hard band (2-12 keV)Soft band (0.2-2 keV) (RASS src)
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Optical Loading – A Problem?Optical Loading – A Problem?
CD 36-1289 : X-ray emission from this V=10.5 star, but none from neighbours at V=6.5 and V=7.6
Several examples like this
- No correlation between source counts and Vmag for bright stars- Consistent with optical loading predictions: 5 counts expected above 200eV only for stars brighter than V=3.75
No optical loading problems : genuine X-ray sources
R Magnitude (USNO)
0.2
-2.0
keV
counts
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Detector problemsDetector problems
Affects one CCD so are detector related
Often appear as non-single events
Very soft spectrum with a peak at 100 eV Events occur mostly within 1 frame
Detector map shows eventsConfined to 1 CCD.
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Detector flashesDetector flashes
Short duration CCD flashes with very soft spectrum
Effect minimized by using single events only below 500 eV
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Starting the NASSStarting the NASS(Newton All-Sky Survey (Newton All-Sky Survey
Aitoff projection galactic coordinates
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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RASS:RASS: 5.0x10-13 (92% of sky)
EMSS:EMSS: 3.0x10-12 (2% 0f sky)
HEAO-1:HEAO-1: 3.6x10-11 (all-sky)
Exosat:Exosat: 5.0x10-11 (?% of sky)
RXTE:RXTE: 1.0x10-11 (all-sky), but with only 1° positional accuracy
X-ray All-Sky Surveys : Flux limitsX-ray All-Sky Surveys : Flux limits
NASS:NASS:6(4.5) 10-13 ergs s-1 cm-2 in the soft band (0.5-2.0 keV)4(3) 10-12 ergs s-1 cm-2 in the hard band (2-10 keV)
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Extended source analysisExtended source analysisSource 2: 2x2 arcmin
FF mode point sources are fitted well by a PSF, e.g. source 4
Low background and tight PSF gives good sensitivityTo extended sources
Enough counts to detect extension in brightest sources
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Example extended sourcesExample extended sources
Easily detected as extended in 14 second exposure
Abell 3581 2 SNRs in SMC
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XMM-Slew
Galaxy ClustersGalaxy Clusters
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Four GalaxiesFour Galaxies
ESO443-IG005Mrk 352
MCG 04-53-021 NGC5899
Non-RASS
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Sources detected in separate slewsSources detected in separate slews
- Source detected in 3 separate slews: Rev 0570, Rev 0573, Rev 0574
- Known ROSAT source (+faint galaxy)
- Evidence for variability (factor ~2)
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Two Merging Two Merging Galaxy PairsGalaxy Pairs
NGC 4748
II Zw 742
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Correlations with ROSATCorrelations with ROSAT
XMM soft
RO
SA
T
Mean XMM/ROSAT ~ 10
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Correlations with ROSATCorrelations with ROSATAll Slew sources:Hardness ratio vs Galactic latitude
Blue circles:No RASS counterpart
Red crosses:RASS counterpart
Hard sources not seen by ROSAT
RASS sources on average softer than non-RASS sources
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Extremely Bright SourcesExtremely Bright Sources
Several LMXB at few hundred c/s
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Conclusions from current Slew analysisConclusions from current Slew analysis
138 slews source-searched (using best strategies): 1596 sources found in 3400 deg² (~10% of sky) ~0.5 sources per square degree
Soft X-ray band detection limit close to ROSAT BS catalogue Hard X-ray band detection limit deepest ever:
> 10× deeper than EXOSAT, HEAO-1 ~ 2.5× deeper than RXTE (only has 1° positional accuracy)
Good sensitivity to extended sources, investigating optimum detection techniques
XMM-Slew positional accuracy ~8″
Aim to recover science from high-background slews
Encountering & solving problems en route …
Aim to issue first slew source catalogue before end of 2005
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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Well Known SourcesWell Known Sources
N132D
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Spurious Sources…Spurious Sources…
… due to crab off-axis !Sources 1 & 3 of Pilot#1
SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton
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ScheduleSchedule- Initial processing of slew data- Initial processing of slew data (finished)(finished)- Solve attitude/astrometry problems – - Solve attitude/astrometry problems – asapasap- Creation of images, source searching, rejection of spurious sources- Creation of images, source searching, rejection of spurious sources (Feb to July)(Feb to July)- - Investigate optimum extended source extraction methodsInvestigate optimum extended source extraction methods (April to Oct)(April to Oct)- Creation of final catalogue for ingestion into XSA- Creation of final catalogue for ingestion into XSA (Aug to Oct) (Aug to Oct)- Ingestion into XSA- Ingestion into XSA (end of November) (end of November)- - Provide flux / upper limits serverProvide flux / upper limits server (early 2006) (early 2006)
- Search co-added slews Search co-added slews (?)(?)- Investigate going down to DET_ML=8 Investigate going down to DET_ML=8 (?)(?)
- - Regular updates with newly processed slewsRegular updates with newly processed slews