1. The XMM-Newton Slew Survey
Richard Saxton1, M. Pilar Esquej14,
Andy Read2, Michael Freyberg3, Bruno Altieri1, Diego Bermejo4, Veronica Lazaro4,
Pedro Rodriguez1
1 ESAC
2 University of Leicester, U.K.
3 MPE, Garching, Germany
4 Universidad Complutense de Madrid, Spain

2. Overview - 390 slew datasets in archive (since Rev 314)
- PN, MOS-1/2 exposures in Medium filter with the observing mode set to that of previous pointed observation
- Average slew length is 70 degrees
- Data initially available for slews longer than 30 mins duration
- Closed slew, open slew, closed slew. Open slew speed = 90 degrees / hour, i.e. on-source time ~14 secs
- Area covered to date ~10000 deg2 (~25% of sky)

3. Initial impressions New operations strategy (from end of 2004):
We can process slew data with a small s/w change (available in SAS 6.5)
MOS PN
PN (eFF)
Slew
direction
Extended full frame streak
of 18 arcsecs
Source extended into a 4 arcmin streak due to 2.6 second frame time
New operations strategy (from end of 2004):
MOS slews will be used for calibration
All PN slews longer than 15 mins will be down-linked and processed and used for science
Medium filter if FF,EFF,LW and Closed for other modes
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

4. Galaxy Clusters
XMM-Slew

5. Extended source analysis
Source 2: 2x2 arcmin
Low background and tight PSF gives good sensitivity
To extended sources
FF mode point sources are fitted
well by a PSF, e.g. source 4
Enough counts to detect extension in brightest sources

6. Example extended sources
Abell 3581
2 SNRs in SMC
Easily detected as extended in 14 second exposure

7. Processing 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 ( keV)

8. UY Vir DSS Image 2’×2’ Total band (0.2-12 keV) Soft band (0.2-2 keV)
Hard band (2-12 keV)
(RASS src)

9. Optical Loading – A Problem?
keV counts
V Magnitude
- 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
CD :
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 optical loading problems – Genuine X-ray sources

10. * Including high background slews
Current Status
(15/05/05)
Initial processing of 374 slews (297 are FF, eFF or LW) – 25% have high background
Images created and source searched for 125 slews giving
1651 sources in total band
1341 sources in soft ( keV) band
243 sources in hard ( keV) band
At faint end, 169 soft-band and
61 hard-band sources, not detected in the total band
Total of 1880 sources in ~4000 deg² ~0.5 sources per square degree
60% have RASS counterpart
Completeness
2005
2010
2015
Equivalent fraction of sky covered
20 %
(25)*
50%
(60)
80%
(100)
Number of sources
4000
(5000)
10000
(12000)
16000
(20000)
* Including high background slews

11. Survey Characteristics
Source Count Distribution
Exposure Time Distribution
4 counts
~ 10 seconds
- Can calculate flux limits for the XMM-Slew survey

12. Flux limits RASS 5.0x10-13 (92% of sky) EMSS 3.0x10-12 (2% 0f sky)
HEAO x10-11 (all-sky)
Exosat 5.0x10-11 (?% of sky)
RXTE x10-11 (all-sky), but with only 1° positional accuracy

13. Mrk 352
ESO443-IG005
MCG
NGC5899
Four Galaxies
Non-RASS

14. Sources 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)

15. Two Merging Galaxy Pairs
NGC 4748
II Zw 742

16. Astrometry Comparison with ROSAT survey positions shows peak at 10”
… but long tail…
median=31” offset
Blue squares:
Number of 2MASS sources
vs. distance to slew source
Green diamonds:
Equivalent distribution for random sky positions
(same number of sources)
Red triangles:
Difference in distributions
i.e. Blue minus Green

17. Attitude Problem AB Dor Two types of positional error
(1) Real error of ~7″
(2) Error of 0-60″ (mean 30″) but only in slew direction
AB Dor
Slew
direction
‘Error ellipse’ around source (slew-oriented)
Optimistically we can remove error (2) by re-processing the raw attitude data (RAF)
A timing error of 1 sec = 90”. Timing supposed to be good to 10 ms while individual attitude points expected to be ok to within 10”.

18. Correlations with ROSAT
Mean XMM/ROSAT=6.2
Mea
Mean XMM/ROSAT = 6.2
ROSAT
XMM soft

19. Correlations with ROSAT
All 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

20. Several LMXB at few hundred c/s
Extremely Bright Sources
Several LMXB at few hundred c/s

21. Correlations with ROSAT
All Slew sources in
Galactic coordinates
Green circles:
RASS counterpart
Red crosses:
No RASS counterpart
No obvious trend

22. Schedule - Initial processing of slew data (finished)
- Solve attitude/astrometry problems – asap
- Creation of images, source searching, rejection of spurious sources (Feb to July)
- Investigate optimum extended source extraction methods (April to Oct)
- Creation of final catalogue for ingestion into XSA (Aug to Oct)
- Ingestion into XSA (end of November)
- Provide flux / upper limits server (early 2006)
Search co-added slews (?)
Investigate going down to DET_ML=8 (?)
- Regular updates with newly processed slews

23. Conclusions from current Slew analysis
- All available (374) Slews processed (~20% of sky)
(Revs , → 100% of sky by mid-2014)
- 77 Slews source-searched (using best strategies):
1200 sources found in 2500 deg² (~6% of sky)
~0.5 sources per square degree
- Soft X-ray band detection limit close to ROSAT All-Sky Survey
- Hard X-ray band detection limit deepest ever:
> 10× deeper than EXOSAT, HEAO-1
~ 2.5× deeper than RXTE (only has 1° positional accuracy)
- XMM-Slew positional accuracy ~6″
Additional ‘attitude-error’ (30″ mean), but only along slew
Confident that this attitude-error can be drastically reduced
- Aim to recover science from high-background slews
- Encountering & solving problems en route – Still on schedule…

24. Conclusions from current Slew analysis
- 125 Slews source-searched (using best strategies):
1880 sources found in 4000 deg² (~10% of sky)
~0.5 sources per square degree
- Soft X-ray band detection limit close to ROSAT BS cat
Hard X-ray band detection limit deepest ever
Good sensitivity to extended sources, investigating optimum detection techniques
- XMM-Slew positional accuracy ~7″
Additional ‘attitude-error’ (30″ mean), but only along slew
Hopeful that this attitude error can be drastically reduced
Aim to recover science from high-background slews
Aim to issue first slew source catalogue before end of 2005
- Encountering & solving problems en route – Still on schedule…

26. Detector problems Affects one CCD so must be detector related
Detector map shows events
Confined to 1 CCD.
Affects one CCD so must be detector related
Often appear as non-single events
Very soft spectrum with a peak at 100 eV
Events occur within 1 frame

27. Spurious Sources…
Sources 1 & 3 of Pilot#1
… due to crab off-axis !

28. Well Known Sources
N132D