M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 1 Status of the XMM-Newton Slew Survey P. Esquej, R. Saxton, B. Altieri, A. Read, M. Freyberg, D. Bermejo, V. Lazaro

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 2 Outline Overview Processing challenges Attitude reconstruction and positional accuracy Spurious sources Extended sources Conclusions

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 3 Overview -PN exposures in Medium filter in FF, eFF and LW modes -Open-slew speed = 90 degrees / hour, i.e. on-source time ~14 secs -Very low background of average ~0.1 c/arcmin 2 -Area covered to date ~6300 deg 2 (~15% of sky) ecliptic coordinates

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 4 Processing strategy -Slew data processing using a small s/w change (available in SAS 6.5) -Tangential projection not valid over whole slew. Divide slew into 1 deg 2 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  ) -Search independently in three bands and produce three catalogues : soft (0.2-2 keV) hard (2-12 keV) total ( keV)

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 5 Current Status Equivalent fraction of sky covered 15% (20)* 45% (55) 80% (~100) Number of sources 4000 (5500) (15000) (25000) Completeness * Including high background slews - Initial processing of 424 slews (FF, eFF or LW) – 25% have high background - Images & exposure maps created and source searched for 220 slews giving 4178 sources in total ( keV) band 2750 sources in soft ( keV) band 844 sources in hard ( keV) band Source density: ~0.65 sources per square degree ~56% have RASS counterpart within 60 arcsec

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 6 Attitude Reconstruction -Crucial in determination of source coordinates -Provided by the AOCS: a star-tracker operates in adition with the Sun-sensor provide the information for reconstructing the astrometry (1 arcsec for pointed observations) -Two types of attitude data can be used during event file processing: Raw Attitude File (RAF) and Attitude History File (AHF) -Different in slew observations than that used for pointed observations

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 7 Astrometry: initial comparison Comparison with ROSAT survey positions shows a wide distribution, with a tail up to 1 arcmin Two types of positional error (1) Real error of ~15″ (2) Error of 0-60″ (mean 30″)

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 8 Attitude 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: ~15 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 Optimal attitude file: RAF subtracted by 0.75 s from every entry

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 9 Achieved astrometric accuracy RASS : 15” (1  )SIMBAD : 8” (1  )

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 10 Spurious sources -Detector flashes: due to low- energy events -Within extended or within halo of bright source: look for images with high number of sources -High background images: spurious detections due to localised background flares -Position suspect: several cases -False detection: background related?

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 11 Extended vs point-like sources FF mode point sources are fitted well by a PSF, e.g. source 4 Low background and tight PSF gives good sensitivity to extended sources Enough counts to detect extension in brightest sources Point-like source Extended source

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 12 Example of extended sources

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 13 Comparison ROSAT / XMM-Newton Mean count rate ratio XMM/ROSAT ~ 10 We can study source variability

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 14 XMM-Newton Slew 1 (XMMSL1) Aitoff projection

M. Pilar Esquej, XMM-Newton European Space Astronomy Centre Page 15 Conclusions 220 slews source-searched (using best strategies): 4013 sources (after removing spurious sources) Sky coverage: ~6300 deg 2 (~15% of sky) ~0.65 sources per square degree XMM-Slew positional accuracy ~8″ 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) Topics under current investigation: optical correlation, refinement of spurious detection, source extension strategy, recovering science from high-background slews, source variability Aim to issue first slew source catalogue (XMMSL1) before end of 2005 Provide an upper limit server in 2006