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XMMSLEWCLN - XMM-Newton Slew Survey Clean Source Catalog, v2.0 |
HEASARC Archive |
Overview
This table contains the 'clean' sample of sources from the second catalog of X-ray sources found in slew data taken by the European Space Agency's XMM-Newton Observatory, XMMSL2 or XMMSLEW, Version 2.0. It has been constructed by members of the XMM-Newton Science Operations Centre (SOC) and the European Photon Imaging Camera (EPIC) consortium on behalf of ESA. This release uses results of work which was carried out within the framework of the EXTraS project ("Exploring the X-ray variable and Transient Sky"), funded from the EU's Seventh Framework Programme under grant agreement no.607452.This is the first release of XMMSL2 which contains data taken between revolutions 314 and 2758. The previous catalog was called XMMSL1_Delta6 and contained slews up to revolution 2441. XMMSL2 has been generated from 2114 slews, executed between 2001-08-26 and 2014-12-31, revolutions 314 to 2758. Not all slews made in this period have been used; slews with particularly high background throughout the slew or which gave processing problems have been rejected.
A full discussion of the differences between XMMSL2 and XMMSL1 is given in Section 12 of the XMMSL2 Users Guide at https://www.cosmos.esa.int/web/xmm-newton/xmmsl2-ug.
Catalog Bibcode
2008A&A...480..611SReferences
The first XMM-Newton slew survey catalogue: XMMSL1.
Saxton R.D., Read A.M., Esquej P., Freyberg M.J., Altieri B., Bermejo D.
<Astron. Astrophys., 480, 611-622 (2008)>
=2008A&A...480..611S (SIMBAD/NED BibCode)
EPIC-pn SLEW-specific PSF parameterisation.
Read, A.M., Saxton, R.D.
XMM-SOC-CAL-SRN-0333
available at https://www.cosmos.esa.int/web/xmm-newton/ccf-release-notes
Optical loading in the XMM-Newton slew source catalogue.
Saxton, R.D., Read, A.M., Robrade, J., Schmitt, J.H.M.M.
XMM-SOC-CAL-TN-0210
available at https://www.cosmos.esa.int/web/xmm-newton/ccf-release-notes
Provenance
This database table was first created by the HEASARC in August 2007 based on the FITS version of XMMSL1D1 (v1.1) of the XMM Slew Catalog. The current version was created in April 2017 based on the FITS version of XMMSL2 (v2.0) of the XMM Slew Catalog obtained from the following URLs: http://nxsa.esac.esa.int/catalogues/xmmsl2_clean.fits.gz (the clean sample), and http://nxsa.esac.esa.int/catalogues/xmmsl2_total.fits.gz (the total sample).The HEASARC has endeavored to retain the same parameter names as in the ESA version, but has changed some so as to conform to the standard HEASARC parameters naming conventions, e.g., all error parameter names which ended in "_err" in the ESA version end in "_error" in this HEASARC version. For other parameters which have had their names changed, their original ESA names are listed in square brackets in their descriptions below.
Description
XMMSL2 has been generated from 2114 slews, executed between 2001-08-26 and 2014-12-31, revolutions 314 to 2758. Not all slews made in this period have been used; slews with particularly high background throughout the slew or which gave processing problems have been rejected. The slews have been processed separately in three energy bands:
Band Energy (keV) Description
8 0.2-12 Total
7 2-12 Hard
6 0.2-2 Soft
to form three distinct surveys which have been subsequently combined to form
one catalog.
There are two related catalogs: a full catalog (the HEASARC Browse table XMMSLEWFUL constructed from the file xmmsl2_total.fits.gz), containing 72,352 detections of sources found with a likelihood of DET_ML > 8, and a "clean" catalog (the HEASARC Browse table XMMSLEWCLN constructed from the file xmmsl2_clean.fits.gz) containing 29,393 sources, where all known bad sources have been removed and where the detection limit has been raised to DET_ML > 10.5 in general and DET_ML > 15.5 for sources found in images with a higher than usual background. Efforts have been made to identify spurious detections and 3,017 of these have been flagged as such in the full catalog.
There is an overlap between the slew paths, which has led to some sources being observed up to 15 times with 4,924 sources being observed two or more times. The full catalog has a significant expected spurious fraction, determined from cross-correlations with other catalogs. A cleaner subset has been created, with sources of likelihood DET_ML > 15.5 (or DET_ML > 10.5, for the soft and total energy bands, taken from images where the background count rate is <= 3 ct/s) and where there is a minimum of 4 background subtracted counts in at least one of the bands. The number of sources and the sky area for the two catalogs is:
Full catalog, sky area = 65,000 deg2:
Band Number of Sources
8 55,969
7 13,927
6 36,189
ALL 72,352
Clean catalog, for band 7, sky area = 65,000 deg2; for bands 6 and 8, the sky area contains 44,000 deg2 of low-background images where sources are accepted with det_ml > 10.5 and 21,000 deg2 of higher background images where sources are accepted with det_ml > 15.5:
Band Number of Sources
8 26,390
7 1,934
6 22,337
ALL 29,393
The median flux is 3.0E-12 ergs/s/cm2 in the total band, 1.2E-12 in the soft band and 9.3E-12 in the hard band in the clean catalog. All sources have been cross-correlated with existing astronomical catalogs and an identification assigned for each source where found. These have been included together with the source category, e.g. Galaxy, flare star etc., as columns in the catalog together with any ROSAT All Sky Survey (RASS) counterpart. The quoted positions in the slew catalog have a 1-sigma error of ~8 arcseconds which for point sources is dominated by the accuracy of the attitude reconstruction during the slewing maneuvers. The statistical position error quoted in the catalog has a median of ~4.2 arcseconds (1 image pixel) for non-extended CLEAN catalog sources. This is usually much larger for extended sources. After correcting for overlaps between slews, 84% of the sky has now been covered. The slew paths pass predominantly through the ecliptic poles as can be seen in the first figure in the XMMSL2 Users Guide at https://www.cosmos.esa.int/web/xmm-newton/xmmsl2-ug, which shows all the slews contained in this catalog release.
Detections in the three energy bands have been combined using a match radius of 30 arcseconds to identify sources detected in more than one band. The match radius is approximately 4 sigma and is reasonable for point sources because of the great scarcity of sources (1 detection per square degree on average) at the flux levels probed by the slew survey.
Spurious detections are produced due to systematic effects with the instruments and detection software. These sources have been screened and flagged ('T' for 'true' or 'F' for 'false') in the different categories described below. When a source is flagged true, the FLAG_COMMENT column gives a more detailed explanation of the problem for each particular source.
VER_INEXT:
This quality flag is used to ensure that only one source is quoted for extended objects; that with the highest det_ml. Two different cases have been found:
- Large extended sources (mainly SNR) that often result in multiple detections of the same object. These have been identified by searching for images with a large number of sources - Other spurious sources (mainly due to Cluster of Galaxies) appear because the technique used for merging detections in the different energy bands is optimal for point-like sources. This consists of considering the same source if their centers lie within 30 arcsec of each other, but this offset has to be bigger for extended sources. This flag has been set to 'T' for 1,481 detections.
VER_HALO:
A halo of false detections is often seen around bright slew sources due to the imperfect modeling of the PSF (a problem also found in the creation of the 3XMM Serendipitous Source Catalog). Due to the reduced exposure time in slew observations this is only important for very bright sources, rate >> 10 ct/s. For flagging this category of spuriousness, the different sources detected in the same image and containing a very bright source have been inspected. If their centers lie within 30 arcsec but corresponding to the same object, the one with the highest det_ml is taken as the non-spurious detection and the rest have been flagged 'T'. 1,248 detections have this flag set.
VER_HIGHBGND:
One of the characteristics of slew exposures is their low background (on average ~0.1 ct/arcmin2). Solar flares may be present, however, and can generate high background sub-images which are not above the threshold used to exclude them. Sources which fall in these patches of high background have been identified and flagged in this category by looking for images with a large number of sources (without being included in the VER_INEXT category of spurious sources explained above). It has been checked that no other bright off-axis source could generate the detections. There are 189 detections with this flag set to 'T'.
VER_NREDG:
In the previous catalog some sources were detected lying on the border of consecutive images of the same slew observation. This no longer occurs and this flag has not been used in XMMSL2.
VER_PSUSP:
This quality flag is related to the astrometry performance and arises after a careful visual examination of the RAF files. The attitude reconstruction of some slews appears to be "turbulent" rather than smooth, so source positions lying in these poorly attitude reconstructed regions are likely to be inaccurate. 1,014 detections have this warning flag set to 'T'
VER_FALSE:
This flag is related to spurious detections not included in the other flags. Examples are cosmic rays, out of field-of-view reflections from Sco X-1 or other bright sources, bad attitude files or bad exposure time. 99 detections have this flag set to 'T'.
VER_OPTLOAD:
This is a warning flag which says that most of the events associated with this source have been removed by filtering. This can be a good indication that the detection has been spuriously created by optical photons. It can also indicate that the source extraction region includes an image defect (such as a bad pixel) or that the source is extremely soft, e.g. a white dwarf. This flag should be used in conjunction with knowledge of the optical magnitude of the object.
Acknowledgments
The identification process has made considerable use of the VizieR catalog access tool, CDS, Strasbourg, France. The original description of the VizieR service was published in A&AS 143, 23. It has used the SIMBAD database, operated at CDS, Strasbourg, France and the NASA/IPAC Extragalactic database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.If the XMMSL2 catalog has been helpful for your research the following acknowledgment would be appreciated:
This research has made use of data obtained from XMMSL2, the Second XMM-Newton Slew Survey Catalog, produced by members of the XMM SOC, the EPIC consortium, and using work carried out in the context of the EXTraS project ("Exploring the X-ray Transient and variable Sky", funded from the EU's Seventh Framework Programme under grant agreement no. 607452).
Technical Details
The XMM-Newton Slew Data Files (SDFs) for EPIC-pn were processed using the odfingest and epproc packages of the public xmmsas-15. For diagnostic reasons, a few parameters were set to non-default values (e.g. keeping also events below 150 eV). For the Slew Survey catalog only EPIC-pn exposures performed in Full Frame (FF), Extended Full Frame (eFF), and Large Window (LW) modes were selected, i.e. modes where all 12 CCDs are integrating (in LW mode only half of each CCD). The corresponding cycle times are 73.36 ms, 199.19 ms, and 47.66 ms, which converts to a scanned distance of 6.6 arcseconds, 17.9 arcseconds, and 4.3 arcseconds per cycle time, respectively. In the Small Window mode only the central CCD is operated and a window of 64 x 64 pixels is read out, i.e. only about 1/3 of a CCD. In the fast modes, Timing and Burst, only 1-dimensional spatial information for the central CCD is available and thus these three modes are not very well suited for source detection.Events are recorded initially in RAW or detector coordinates and have to be transformed, using the satellite attitude history, into sky coordinates. The tangential plane geometry commonly used to define a coordinate grid for flat images is only valid for distances of 1-2 degrees from a reference position, usually placed at the center of the image. To avoid this limitation, slew datasets were divided into roughly one square degree event files, attitude corrected and then converted into images. An overlap of about 20% has been allowed between subimages to avoid problems with sources which lie at the edge of a subimage.
Source searching used a semi-standard 'eboxdetect (local) + emask + esplinemap + eboxdetect (map) + emldetect' method, tuned to about zero background, and performed on a single image containing just the single events (pattern = 0) in the 0.2-0.5 keV band, plus single and double events (pattern = 0-4) in the 0.5-12.0 keV band.
The attitude information of the XMM-Newton satellite is provided by the Attitude and Orbit Control Subsystem (AOCS). A star tracker co-aligned with the telescopes allows up to a maximum of five stars to be continuously tracked giving accurate star position data every 0.5 seconds, which operates in addition to the Sun sensor that provides a precise Sun-line determination. Such information is processed resulting in an absolute accuracy of the reconstructed astrometry of typically 1 arcsecond during pointed observations. For the open-loop slews, large slews outside the star-tracker field of view of 3 x 4 degrees, the on-board software generates a three axis momentum reference profile and a two-axis (roll and pitch) Sun-sensor profile, both based on the ground slew telecommanding. During slew maneuvering a momentum correction is superimposed onto the reference momentum profile and, as there are no absolute measurements for the yaw axis, a residual yaw attitude error exists at the end of each slew that may be corrected in the final closed-loop slew. To process slew data, attitude information is taken from a Raw Attitude File (RAF) which stores attitude points every 40-60 seconds. The times quoted in the RAF are offset from spacecraft time by 0.75 seconds, which has to be corrected in the software, otherwise a 1 arcminute offset in source positions is seen along the slew direction. Initially the correction was performed in the slew-specific software but from SAS 7.0 has been included in the general SAS software. The SAS astrometry software interpolates between the rather sparse RAF points using a curve fit. Several RAFs have been found to contain one bad attitude point which is sufficient to totally corrupt the attitude solution over a considerable section of the slew. In other slews a part or all of the attitude seems to be turbulent rather than smooth. It is not known why this occurs and no attempt to fix it has been made. Sources affected by these attitude problems have a position suspect (VER_PSUSP) flag set to true. The error introduced in the source positions can be of the order of 1 arcminute.
A sample of 16,281 non-extended sources from the clean catalog with matches in the ROSAT All-Sky Survey have been cross-correlated with the WISE catalog (Cutri et al. 2012). The histogram of the positional offsets exhibits a distribution that has a 1-sigma offset of 7.1 arcseconds and 90% of the matches lie within 11.3 arcseconds.
Reliability
By comparing positions of a well-constructed sample of reliable slew sources with the WISE catalog it was found that 90% have a WISE match within 11.3". We can use this to gauge the reliability of other sub-samples of sources. In the table below we look at the effect of varying detection likelihood on the percentage of sources that is found in WISE within the 11.3" radius. Only point sources (extension parameter < 1.0), which are not flagged as BAD, and where the number of counts > 4 in at least one of the bands, have been used.
Band MIN_DET_ML Nsample Percentage
Total
8 10.5/15.5 24,993 83.3
8 15.5 17,155 89.7
Hard
7 10.5/15.5 2,975 68.7
7 15.5 1,601 81.4
Soft
6 10.5/15.5 21,197 86.6
6 15.5 17,321 89.8
All Bands
6,7 or 8 10.5/15.5 28,285 81.2
6,7 or 8 12.0/15.5 25,668 84.0
6,7 or 8 13.0/15.5 24,036 85.5
6,7 or 8 14.0/15.5 22,512 86.8
6,7 or 8 15.5 20,393 88.3
MIN_DET_ML represents the minimum detection likelihood for low background images (first number) and high background images (second number) or for both if just one number, where a low background image is defined as having IMAGE_BG_RATE<=3.0. A full assessment of the spurious content of the catalog has not yet been made. The table above gives an indication of the reliability of samples based on different cuts in the detection likelihood compared with a sample with a ROSAT counterpart which is assumed to be free of spurious sources. The statistical error in the XMM-Newton slew position has been ignored in the matching process and so it is natural that the lower significance sources should have a lower match rate. Nevertheless, the hard band (band 7) lower significance sources have a particularly low match rate with WISE within 11.3" and for this reason the CLEAN sample has been re-defined to exclude sources with DET_ML_B7 < 15.5 which are not positively detected in the total or soft bands.
Identifications
All sources detected in the survey have been correlated with different catalogs in order to identify the XMM-Newton slew sources with previously known objects. The search for counterparts uses the following catalogs and databases in the listed order:Catalog Search Radius (arcsec) SIMBAD 12 Abell galaxy clusters 180 Zwicky galaxy clusters 180 Einstein IPC 120 EXOSAT slew 45 ROSAT All-Sky Survey 90 ROSAT pointed PSPC observations (2RXP) 30 ROSAT pointed HRI observations (1RXH) 30 INTEGRAL source catalog (IGR) 60 XMM-Newton serendipitous survey (3XMM) 12 NED 12Counterparts have been allocated depending on where they are found, with identifications in SIMBAD given the greatest precedence and NED the least. The one exception is sources found in the Abell or Zwicky catalogs which are extended in the slew catalog (EXT_B6 > 0.5 or EXT_B7 > 0.5 or EXT_B8 > 0.5). These have been assigned the Abell or Zwicky counterpart name rather than that given in SIMBAD.
The cross-correlation with the ROSAT all-sky survey was split into two. Bright source catalog (BSC) sources have been matched to a radius of 1 arcminute and the faint source catalog (FSC) sources to 1.5 arcminutes. Of the clean catalog slew sources, 59% have a ROSAT counterpart. This increases to 69% if we consider only sources with a soft band (B6) detection.
Results from the identification process appear in the final catalog in the columns:
IDENT: name of the source.
ALTIDENT: alternative name of the source.
ID_DIST: distance in arcsec between the slew source and the identification.
ID_CATEGORY: type of the identified source that, when existing, has been
extracted from the catalogs (it is not very homogeneous because
type convention is very variable between and sometimes within
catalogs).
RASSNAME: the closest RASS match.
RASSDIST: distance in arcseconds to the closest RASS match.
Given the statistical nature of the identification process these should be
regarded as suggested rather than definitive counterparts.
Detection Limits
The minimum detectable count rate for a given band is ~0.4 ct/s, for a source which passes through the center of the detector and for typical background levels. A rough flux upper limit is then available by multiplying this count rate by the conversion factors specified below. This is for each band:Band Energy (keV) Flux limit (10-12 ergs/s/cm2) Total 0.2-12 1.3 Hard 2-12 3.7 Soft 0.2-2 0.57
Flux Conversion
Source fluxes have been calculated from count rates based on energy conversion factors assuming a spectral model of an absorbed power-law with NH = 3.0 x 1020 cm2 and a slope = 1.7 (see XMM Science Survey Centre memo, SSC-LUX TN-0059 for a general description of the technique). The energy conversion factors used here are 3.159, 9.144 and 1.436 for the total, hard and soft bands, respectively, in units of 1.0E-12 ergs/s/cm2 to convert from the source count rate (ct/s) to flux in these energy bands.Parameters
XMMslew_Name
This is the official name for sources detected in the XMM-Newton slew survey.
It starts with the prefix, XMMSL2, evolving from XMMSL1, the IAU-registered
designator, and then encodes the J2000 sky position, e.g. XMMSL2
J010537.6+364858. The name is assigned in two passes. When the three
independent energy band source lists are combined to form one catalog the
source name is set using the position in the band where the DET_ML likelihood
is the highest. A second pass is then performed such that sources which have
been observed in more than one slew are given the same name. Again, priority
is given depending on the detection likelihood. Note that the combination of
XMMSLEW_NAME and observation number (OBSID) is unique. Detections are deemed
to be from the same source if their centers lie within 30 arcseconds of each
other. Note that the statistical position error (RADEC_ERROR) calculated by
the source search software is not used in this calculation. This is because
the systematic error in the slew attitude reconstruction dominates the error
budget in many cases. Given the scarcity of slew sources on the sky, 30" was
found to be a reasonably robust match radius for point sources. It is not so
good for extended sources and the catalog may contain multiple detections of
the same extended source with different names. [UNIQUE_SRCNAME in original ESA
catalog]
ObsID
This is the XMM-Newton observation number assigned to the slew by the
satellite scheduling system. Slew observations always begin with a 9 to
distinguish them from pointed observations, followed by a 4-digit satellite
orbit number and a 5-digit slew designator, e.g. 9031400004, refers to the
second slew of revolution 314.
Sourcenum
This is a number which uniquely identifies each detection in an observation.
RA
The Right Ascension of the source in the selected equinox. This was given in
J2000.0 coordinates and to a precision of 8 significant digits in decimal
degrees in the original table. In the event of a detection in more than
one energy band, the position is taken from the band with the highest
detection likelihood.
Dec
The Declination of the source in the selected equinox. This was given in
J2000.0 coordinates and to a precision of 8 significant digits in decimal
degrees in the original table. In the event of a detection in more than
one energy band, the position is taken from the band with the highest
detection likelihood.
RADec_Error
The statistical error of the source position, in arcseconds, as returned by
the source detection software.
LII
The Galactic Longitude of the source.
BII
The Galactic Latitude of the source.
HR1
The hardness ratio of the XMM source, defined as
HR1 = (COUNT_RATE_B7 - COUNT_RATE_B6) / (COUNT_RATE_B7 + COUNT_RATE_B6)
where COUNT_RATE_B7 is the hard band count rate and COUNT_RATE_B6 is the soft
band count rate. This has been calculated for the 1,936 sources which have a
positive detection in both bands.
HR1_Error
The error in the hardness ratio, calculated as
sqrt(COUNT_RATE_B7_ERROR2 + COUNT_RATE_B6_ERROR2) / (COUNT_RATE_B7 +
COUNT_RATE_B6)
where COUNT_RATE_B7_ERROR and COUNT_RATE_B6_ERROR are the errors in the hard
and soft band count rates, respectively.
Time
The start time of the slew containing this source. [DATE_OBS
in original ESA catalog]
End_Time
The end time of the slew containing this source. [DATE_END
in original ESA catalog]
Scts_B8
The number of background-subtracted counts, in the total energy band (0.2-12
keV). This number has been corrected for photons scattered outside the source
region due to the Point Spread Function (PSF).
Scts_B8_Error
The statistical 1-sigma error in the total-band source counts.
Scts_B7
The number of background-subtracted counts, in the hard energy band (2-12
keV), corrected for the PSF.
Scts_B7_Error
The statistical 1-sigma error in the hard-band source counts.
Scts_B6
The number of background-subtracted counts, in the soft energy band (0.2-2
keV), corrected for the PSF.
Scts_B6_Error
The statistical 1-sigma error in the soft-band source counts.
X_Ima_B8
The X position of the source in the total-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
Y_Ima_B8
The Y position of the source in the total-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
X_Ima_B7
The X position of the source in the hard-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
Y_Ima_B7
The Y position of the source in the hard-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
X_Ima_B6
The X position of the source in the soft-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
Y_Ima_B6
The Y position of the source in the soft-band image in image pixels. Each
pixel covers an area of 4.1" x 4.1".
Ext_B8
The spatial extension of the source in the total energy band, in pixels. This
measures the deviation from a point source of the spatial distribution of the
source counts. It is defined as the sigma of a Gaussian which would need to
be convolved with the point spread function (PSF) to produce the observed
counts distribution. The software (emldetect) fits sources out to a maximum
extent of 20 pixels. Each pixel covers an area of 4.1" x 4.1".
Ext_B8_Error
The statistical 1-sigma error in the total-band spatial extension, in pixels.
Ext_B7
The spatial extension of the source in the hard energy band, in pixels. This
measures the deviation from a point source of the spatial distribution of the
source counts. It is defined as the sigma of a Gaussian which would need to
be convolved with the point spread function (PSF) to produce the observed
counts distribution. The software (emldetect) fits sources out to a maximum
extent of 20 pixels. Each pixel covers an area of 4.1" x 4.1".
Ext_B7_Error
The statistical 1-sigma error in the hard-band spatial extension, in pixels.
Ext_B6
The spatial extension of the source in the soft energy band, in pixels. This
measures the deviation from a point source of the spatial distribution of the
source counts. It is defined as the sigma of a Gaussian which would need to
be convolved with the point spread function (PSF) to produce the observed
counts distribution. The software (emldetect) fits sources out to a maximum
extent of 20 pixels. Each pixel covers an area of 4.1" x 4.1".
Ext_B6_Error
The statistical 1-sigma error in the soft-band spatial extension, in pixels.
Det_ML_B8
The detection likelihood in the total energy band (0.2-12 keV).
Det_ML_B7
The detection likelihood in the hard energy band (2-12 keV).
Det_ML_B6
The detection likelihood in the soft energy band (0.2-2 keV).
Ext_ML_B8
The likelihood of the source being extended in the total band.
Ext_ML_B7
The likelihood of the source being extended in the hard band.
Ext_ML_B6
The likelihood of the source being extended in the soft band.
Bg_Map_B8
The background counts per pixel for the total band.
Bg_Map_B7
The background counts per pixel for the hard band.
Bg_Map_B6
The background counts per pixel for the soft band.
Exp_Map_B8
The effective on-axis exposure time in the total energy band, in seconds.
Exp_Map_B7
The effective on-axis exposure time in the hard energy band, in seconds.
Exp_Map_B6
The effective on-axis exposure time in the soft energy band, in seconds.
Flux_B8
The source flux in the total energy band, in erg/cm2/s. Source fluxes have
been calculated from count rates based on energy conversion factors assuming
a spectral model of an absorbed power-law with NH = 3.0 * 1020 cm-2 and
a slope = 1.7 (see XMM Science Survey Center memo SSC-LUX TN-0059 for a
general description of the technique). The energy conversion factors used
here to convert between the source count rate in ct/s to flux in these energy
bands in units of 10-12 erg/s/cm2 are the following:
Band Conv. Factor
Total 3.159
Hard 9.144
Soft 1.436
Flux_B8_Error
The error in the total-band source flux, in erg/cm2/s.
Flux_B7
The source flux in the hard energy band, in erg/cm2/s. Source fluxes have
been calculated from count rates based on energy conversion factors assuming
a spectral model of an absorbed power-law with NH = 3.0 * 1020 cm-2 and
a slope = 1.7 (see XMM Science Survey Center memo SSC-LUX TN-0059 for a
general description of the technique). The energy conversion factors used
here to convert between the source count rate in ct/s to flux in these energy
bands in units of 10-12 erg/s/cm2 are the following:
Band Conv. Factor
Total 3.159
Hard 9.144
Soft 1.436
Flux_B7_Error
The error in the hard-band source flux, in erg/cm2/s.
Flux_B6
The source flux in the soft energy band, in erg/cm2/s. Source fluxes have
been calculated from count rates based on energy conversion factors assuming
a spectral model of an absorbed power-law with NH = 3.0 * 1020 cm-2 and
a slope = 1.7 (see XMM Science Survey Center memo SSC-LUX TN-0059 for a
general description of the technique). The energy conversion factors used
here to convert between the source count rate in ct/s to flux in these energy
bands in units of 10-12 erg/s/cm2 are the following:
Band Conv. Factor
Total 3.159
Hard 9.144
Soft 1.436
Flux_B6_Error
The error in the soft-band source flux, in erg/cm2/s.
Count_Rate_B8
The total band count rate, in counts/second. [RATE_B8 in the
original catalog]
Count_Rate_B8_Error
The error in the total band count rate. [RATE_B8_ERR
in the original catalog]
Count_Rate_B7
The hard band count rate, in counts/second. [RATE_B7 in the
original catalog]
Count_Rate_B7_Error
The error in the hard band count rate. [RATE_B7_ERR in
the original catalog]
Count_Rate_B6
The soft band count rate, in counts/second. [RATE_B6 in the
original catalog]
Count_Rate_B6_Error
The error in the soft band count rate. [RATE_B6_ERR in
the original catalog]
RA_B8
The Right Ascension of the total-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
Dec_B8
The Declination of the total-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
RADec_B8_Error
The statistical 1-sigma error in the total-band source
position, in arcseconds.
LII_B8
The Galactic Longitude of the total-band source, in degrees.
BII_B8
The Galactic Latitude of the total-band source, in degrees.
RA_B7
The Right Ascension of the hard-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
Dec_B7
The Declination of the hard-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
RADec_B7_Error
The statistical 1-sigma error in the hard-band source
position, in arcseconds.
LII_B7
The Galactic Longitude of the hard-band source, in degrees.
BII_B7
The Galactic Latitude of the hard-band source, in degrees.
RA_B6
The Right Ascension of the soft-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
Dec_B6
The Declination of the soft-band source source in the selected equinox.
This was given in J2000.0 coordinates and to a precision of 8 significant
digits in decimal degrees in the original table.
RADec_B6_Error
The statistical 1-sigma error in the soft-band source
position, in arcseconds.
LII_B6
The Galactic Longitude of the soft-band source, in degrees.
BII_B6
The Galactic Latitude of the soft-band source, in degrees.
Val_Flag
This flag is set to 'CLEAN_SAMPLE' to indicate that the source is
included in the clean subset, else it is set to 'XXXXXXXXXXXX'.
Srcname_B8
The source name defined in the total-band list. The format
is 'xs' followed by the revolution number, the observation ID and the
source position, e.g., 'xs0841_9084100002_12:57:07.5+01:50:42'.
Srcname_B7
The source name defined in the hard-band list. The format
is 'xs' followed by the revolution number, the observation ID and the
source position, e.g., 'xs0841_9084100002_12:57:07.5+01:50:42'.
Srcname_B6
The source name defined in the soft-band list. The format
is 'xs' followed by the revolution number, the observation ID and the
source position, e.g., 'xs0841_9084100002_12:57:07.5+01:50:42'.
Ximname_B8
The name of the image containing the total-band detection.
Ximname_B7
The name of the image containing the hard-band detection.
Ximname_B6
The name of the image containing the soft-band detection.
Ver_Inext
If set to 'T' (true), this flag notes that a detection has been
found within an extended source and is probably false. This flag is used
to ensure that only one source is quoted for the large supernova remnants.
For more details, see the Description section above.
Ver_Halo
If set to 'T' (true), this flag indicates that a detection lies
within the point spread function, or halo, of a very bright source, and is
probably spurious. For more details, see the Description section above.
Ver_Hibgnd
If set to 'T' (true), this flag indicates that the source lies
within a bright region, caused by high background, and is probably spurious.
For more details, see the Description section above.
Ver_Nredg
If set to 'T' (true), this flag indicates that the source has
been detected in two consecutive images of the same slew. This can occur if
the source lies on the border between slews and implies that the position of
the source is unlikely to be accurate. For more details, see the Description
section above.
Ver_Psusp
This flag indicates that the quoted position of the source is
likely to be inaccurate. In a few slews, the attitude reconstruction is poor
and, in these cases, the actual position of the source is difficult to
determine, and can be wrong by an arcminute.
Ver_False
This is a catch-all for problems not included in the other flags.
In the catalog, 99 detections have this flag set to 'T' (true). Reasons
include: the exposure time has been calculated as zero, a detection due to a
very bright source, e.g. SCO X-1, out of the field of view, a possible cosmic
ray or a very bad attitude reconstruction.
Flag_Comment
A comment which explains why a particular source flag has been
set to true.
Name
Cross-correlations of the positions of the slew sources with astronomical
databases and catalogs have been performed (see the Identification section
above for more details). This parameter lists the catalog name of the best
match. [IDENT in the original catalog]
Alt_Name
An alternative designation for the best-matched source. [ALTIDENT in the
original catalog]
RASS_Name
The name of the closest ROSAT All-Sky Survey (RASS) source to the position of
the XMM-Newton Slew source. [RASSNAME in the original catalog]
ID_Category
The source type, as determined by SIMBAD, NED, and the other resources used
in the cross-matching process. This is directly taken from the catalog in
question, and no attempt has been made to rationalize the values.
ID_Resource
The astronomical database or catalog from which the best match has been
selected, e.g., SIMBAD, NED, etc.
ID_Offset
The angular distance in arcseconds between the best match candidate and the
XMM-Newton Slew Survey source. [ID_DIST in the original catalog]
RASS_Offset
The angular distance between the best matching ROSAT source and the
XMM-Newton Slew Survey source, in arcseconds. [RASS_DIST in the original
catalog]
Mode_ID
The observing mode of the EPIC-pn camera, where 'FF' means full-frame mode,
'eFF' extended full-frame mode, and 'LW' means large window mode.
Image_Bg_Rate
The peak background count rate in the image from which the source was
extracted, in counts/second. This is measured as the count rate, over the
whole image, for events with energy > 10 keV (PI > 10000). It is quoted to a
resolution of 0.1 ct/s and is used to determine the overall background
environment in which a source was detected. This value is used in the
creation of a clean sub-sample of the catalog (see Description section above).
Generally, the higher this value, the greater the probability that the source
is spurious. This is especially true if the detection likelihood of the
source is less than 15.5. The value has been tabulated for images with a
background rate greater than 2 ct/s. For quieter images the value has been
artificially set to 1.9 ct/s.
Subimage_Time
The start time of the subimage in which the source is located. [MJD_START in
the original catalog]
Subimage_End_Time
The end time of the subimage in which the source is located. [MJD_STOP in
the original catalog]
Ver_Optload
This flag indicates that the source may suffer from optical loading if set to
'T' (true).
Filtered_Counts
The number of counts found within a 1 arcminute radius about the source
position after standard filtering is applied. [FILT_COUNTS in the original
catalog]
Unfiltered_Counts
The number of counts found within a 1 arcminute radius about the source
position with no filtering applied. [UNFILT_COUNTS in the original catalog]
XMMSL1_Name
The name of the same source in the previous XMMSL1 catalog if existing.
[US_XMMSL1 in the original catalog]
Extras_Source_Number
This release of XMMSL2 makes use of work carried out within the framework of
the EXTraS project. XMMSL2 is closely linked to the long-term variability
(LTV) catalog within EXTraS, and this parameter provides the corresponding
source number value (SRCID) within the EXTraS LTV catalog. [US_EXTRAS in the
original catalog]
Class
The HEASARC Browse object classification, based on the value of the
ID_CATEGORY parameter.
Contact Person
Questions regarding the XMMSLEWCLN database table can be addressed to the HEASARC Help Desk.Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:37:22 EDT
- HEASARC Director: Dr. Andy Ptak
- NASA Official: Dr. Andy Ptak
- Web Curator: J.D. Myers
- Last Modified: 16-Sep-2024