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XMMOMSUSS: Help

XMMOMSUSS - XMM-Newton Optical Monitor Serendipitous UV Source Survey Catalog


Overview

The XMM-OM Serendipitous Ultra-violet Source Survey (SUSS) is a catalog of UV sources detected serendipitously by the Optical Monitor (OM) on-board the European Space Agency's (ESA's) XMM-Newton observatory. It has been created at the University College London's (UCL's) Mullard Space Science Laboratory (MSSL) on behalf of ESA and is a partner resource to the 2XMM serendipitous X-ray source catalogue.

The catalog contains source detections drawn from 2,417 XMM-OM observations in up to three broad band UV filters made between 2000 February 24 and 2007 March 29. All datasets included were publicly available by 2007 May 01 but note that, due to screening criteria, not all public observations are included in this catalog. Taking account of substantial overlaps between observations, the net sky area covered independently is 29 - 54 square degreees, depending on UV filter. The primary content of the catalog is filter-dependent source positions and magnitudes, and these are accompanied by profile diagnostics and variability statistics.

The XMM-OM SUSS catalog contains 753,578 UV source detections above a signal-to-noise threshold limit of 3-sigma which relate to 624,049 unique objects. A significant fraction of sources (12% - UVW2, 11% - UVM2, 11.% - UVW1) are visited more than once during XMM operation, and a large fraction of sources (38% - UVW2, 23% - UVM2, 22% - UVW1) are observed more than once per filter during an individual visit. UVW2, UVM2 and UVW1 refer to the filter bandpasses defined in the Source Properties: Filter Set section of the MSSL documentation for this catalog: http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/SourcePropertiesFilters.shtml. Consequently, the scope for science based on temporal source variability on timescales of hours to years is broad.

The positional accuracy of the catalog detections is typically 1.0 arcsec (1-sigma confidence radius) with a median positional error of 0.67 arcsec. The median AB magnitude of the catalog detections in the three UV bands is 19.56 (UVW2), 20.23 (UVM2) and 20.69 (UVW1). 20% of sources have AB magnitudes fainter than 20.28 (UVW2), 20.97 (UVM2) and 21.54 (UVW1).

As part of quality evaluation for the catalog, each field has been tested for astrometric accuracy and visually screened for cosmetic problems, compromising aspect anomalies, stray light, large extended sources and telemetry dropouts. Observations affected by these issues (11.2%) have been removed from the catalog sample. Furthermore, 2% of all observations were selected at random where each source in this sample was tested for falsehood, spuriousness and accuracy of quality flagging. The results of this detailed screening are included in the full documentation.

The processing used to generate the catalog is based on the SAS8.0 pipeline developed for the pipeline reduction of all XMM observations. This version includes a number of significant improvements over the previous data processing system (as used by the SSC in routine processing of XMM-Newton data on behalf of ESA). These improvements include a more robust detection scheme for sources close to the limit of sky background, refined quality flagging and a higher success rate (90%) for refined aspect corrections.


References

The XMM-OM Serendipitous Ultra-violet Source Survey (SUSS) has been created at the University College London's (UCL's) Mullard Space Science Laboratory (MSSL) on behalf of ESA and is a partner resource to the 2XMM serendipitous X-ray source catalog.

Provenance

This HEASARC database table contains the XMM-OM SUSS catalog, released by ESA on 2008 July 16, and obtained from the XMM-Newton Science Archive (http://xmm.esac.esa.int/xsa). It is also available as the gzipped FITS file http://heasarc.gsfc.nasa.gov/FTP/xmm/data/catalogues/XMM-OM-SUSSv1.0-20080716.fits.gz.

Data Caveats

Known issues with this catalog are documented at http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/KnownIssues.shtml

Parameters

Name
The IAU-designated source name of format XMMOM JHHMMSS.S+DDMMSS.

N_Summary
This is a reference number for the XMM-Newton pointing in which the particular detection was made, providing a cross-referencing system allowing users to couple a source to its parent observation.

ObsID
Each XMM pointing has an exclusive 10-digit observation identification number or OBSID. This column contains the OBSID of the observation from which the source detection originates.

SrcID
Source detection is performed in the XMM pipeline when the SAS task omdetect passes across each image obtained during a pointing. Source lists created from observations with the same instrument filter are combined and parameters of an individual source detected within different exposures are averaged. Within each combined source list created by the pipeline a source is given a unique reference number. The combination of OBSID and SRCID allows the user to trace the origins of each source in the catalog. Note well that SRCID is not a unique number within the UV catalog.

Src_Num
This is the unique reference number for the source, internal only to the UV catalog.

UVW2_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

UVM2_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

UVW1_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

U_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

B_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

V_Srcdist
This parameter provides the angular distance in arcseconds of the source from its nearest detected celestial neighbour in the specified band. It allows the user to assess the probability of source confusion, contamination or misidentification.

RA
The measured Right Ascension of the source in the selected equinox. The onboard pointing 'knowledge' of the XMM-Newton spacecraft is good to a few arcsecs. All fields included within the UV catalog have had small order astrometric corrections performed upon them by correlating detected sources with the positions of USNO-B catalog optical objects. Note that the error provided in the error_radius parameter does not include the systematic uncertainty remaining after the astrometric correction No proper motion corrections have been attempted.

Dec
The measured Declination of the source in the selected equinox. The onboard pointing 'knowledge' of the XMM-Newton spacecraft is good to a few arcsecs. All fields included within the UV catalog have had small order astrometric corrections performed upon them by correlating detected sources with the positions of USNO-B catalog optical objects. Note that the error provided in the error_radius parameter does not include the systematic uncertainty remaining after the astrometric correction No proper motion corrections have been attempted

Error_Radius
The statistical 1-sigma error in arcseconds attached to the measured source position. The RA and Dec errors are averaged with no weights to produce thisparameter.

LII
The Galactic Longitude of the source at epoch 2000.0.

BII
The Galactic Latitude of the source at epoch 2000.0.

N_ObsID
Over the mission lifetime, XMM-Newton has revisited many fields or observed sources with overlapping fields. N_OBSID records the number of times a source has been detected during separate observations. Note that this is distinct from the number of times XMM has revisited the field. There may have been occasions where an observation was not deep enough to re-detect a specific source, or the source itself is variable. The criteria for matching a source over different epochs is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same observation meet the matching criteria for another observation, the nearest source is adopted as the match.

N_UVW2_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

N_UVM2_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

N_UVW1_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

N_U_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

N_B_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

N_V_Exposure
During an individual observation, the OM may obtain multiple images through the same filter. These may occur through repeat exposures or by mosaicing the field with small sub-windows (this was a common practice during the early phases of the mission in order to avoid telemetry saturation). This parameter provides the number of separate images of a specific filter, taken over a single observation that contain the source. The criteria for matching a source over different exposures is that the positions are separated by < 1.5" and < 3 sigma. In cases where multiple sources within the same exposure meet the matching criteria for another image, the nearest source is adopted as the match.

UVW2_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

UVM2_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

UVW1_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

U_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

B_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

V_SNR
This parameter contains the significance of a source detection in the specified band above the data noise, in sigma. Data noise contains contributions from the background and source. Detector noise is negligible. Significance is calculated on raw count rates, uncorrected for photon coincidence losses.

UVW2_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

UVW2_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

UVM2_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

UVM2_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

UVW1_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

UVW1_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

U_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

U_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

B_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

B_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

V_Rate
This parameter contains the background-subtracted source count rate in the specified band corrected for coincidence loss using the standard calibration polynomial contained within the XMM CAL, in counts per second. Due to the nature of the OM detector, sources with count rates >v5 count/sec suffer from increasing quantities of photon coincidence loss where two photons arriving at the same location of the detector within one readout cycle cannot be distinguished. The effect is correctable using a count rate-dependent function up to corrected count rates of 400 count/sec.

V_Rate_Error
The 1-sigma uncertainty in counts per second determined for the coincidence-corrected source count rate recorded in the corresponding count rate parameter for this band.

UVW2_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

UVW2_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

UVM2_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

UVM2_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

UVW1_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

UVW1_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

U_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

U_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

B_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

B_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

V_AB_Flux
This parameter contains the AB flux in the specified band calculated using the conversion factor (CF) contained within the XMM CAL, in erg/cm2/s/Angstrom. The conversion from coincidence-corrected source count rate to AB flux occurs through a simple filter-dependent, multiplicative factor: FILTER_AB_FLUX = CF * FILTER_RATE.

V_AB_Flux_Error
The 1-sigma uncertainty determined for the AB flux of the source recorded in the corresponding band, in erg/cm2/s/Angstrom.

Uvw2mag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Uvw2mag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Uvm2mag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Uvm2mag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Uvw1mag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Uvw1mag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Umag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Umag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Bmag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Bmag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Vmag_Ab
This parameter contains the AB magnitude of the source in the specified band calculated using the zero point magnitude (AZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to AB magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_AB = AZP - 2.5log(FILTER_RATE).

Vmag_AB_Error
The 1-sigma uncertainty determined for the AB magnitude of the source recorded in the corresponding FILTERMAG_AB parameter.

Uvw2mag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Uvw2mag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

Uvm2mag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Uvm2mag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

Uvw1mag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Uvw1mag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

Umag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Umag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

Bmag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Bmag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

Vmag_Vega
This parameter contains the Vega (Johnson) magnitude of the source in the specified band calculated using the zero point magnitude (VZP) contained within the XMM CAL. The conversion from coincidence-corrected source count rate to Vega (Johnson) magnitude occurs through the standard logarithmic expression with filter-dependent, zero points: FILTERMAG_VEGA = VZP - 2.5log(FILTER_RATE).

Vmag_Vega_Error
The 1-sigma uncertainty determined for the Vega (Johnson) magnitude in the specified band of the source recorded in the corresponding FILTERMAG_VEGA parameter.

UVW2_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

UVW2_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

UVM2_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

UVM2_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

UVW1_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

UVW1_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

U_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

U_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

B_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

B_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

V_Chi2
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic (Chi-squared per degrees of freedom) measures the short-term variability of a source in a specified band:

  FILTER_CHI2 = The sum of ((CCRi - FILTER__RATE)2 / FILTER__RATE) / (N - 1),
  

where CCRi represents the coincidence-corrected count rates from the sample of N independent source detections per OBSID per filter. The larger the value of the reduced-Chi-squared statistic, the more variable the source. This statistic is most suitable for selecting sources which vary consistently over the duration of the observation.

V_Maxdev
Many single observations (OBSIDs) yield multiple detections of a source through the same filter. Multiple detections provide us with a means to detect variable sources on timescales of hours. The reduced-Chi-squared statistic FILTER_CHI2 can, in certain instances, be relatively insensitive to brief flare events sampled by a single measurement. This parameter contains another statistic, FILTER_MAXDEV, which is more suited for picking out flare events: it is simply a measure of the most deviant point from the median of CCRi for the specified band, in units of sigma.

UVW2_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

UVM2_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

UVW1_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

U_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

B_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

V_Major_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the long axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

UVW2_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse.

UVM2_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse

UVW1_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse

U_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse

B_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse

V_Minor_Axis
Using 1st order moment analysis, the size on the sky and ellipticity of sources is determined. This parameter records the full-width half-maximum (FWHM) in arcseconds of the source in the specified band along what is considered to be the short axis of the elliptical source. Note that not all sources in the sample are necessarily well-described by an ellipse

UVW2_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

UVM2_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

UVW1_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

U_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

B_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

V_Position_Angle
The position angle on the sky in degrees subtended by the major axis of the source in the specified band and the direction of J2000 North. The angle increases as the axis rotates from north to east.

UVW2_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

UVM2_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

UVW1_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

U_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

B_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

V_Quality_Flags
Each source passes through an automatic screening process in order to isolate potential problems with either the location or brightness recorded within the catalog. The results of these tests are stored in a Boolean sense (i.e passed or failed) within the 10-character string contained in this parameter. The meaning of each flag is summarized below, whereas a full description of the algorithms used to set the flags is presented in the Data Processing : Quality Flags section, http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/DataProcessingQualityFlags.shtml

The word 'source' below includes both the source and background extraction regions.

   Byte i  Description

      0    Source lies over a cosmetic detector defect (bad pixel)
      1    Source lies potentially over a readout streak originating from
           a bright field object
      2    Source lies potentially over a ghost ring originating from a bright
           field object
      3    Source lies potentially over a diffraction spike originating from
           a bright field object
      4    Source lies potentially within a region background containing a
           modulo-8 fixed pattern
      5    Source lies within the central image, where the background is
           potentially contaminated by scattered light
      6    Potential source confusion with an object detected nearby
      7    Source aperture lies across the outer edge of a raw detector image
      8    A point source which lies within, or partially-within, an extended
           source
      9    Noise spike
  

A source with FILTER_QUALITY_FLAGS = 'FFFFFFFFFF' passes all of the above tests. As an example, a source situated over a bad pixel, on a diffraction spike and at the edge of an image will have a parameter value of 'TFFTFFFTFF'.

UVW2_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.

UVM2_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.

UVW1_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.

U_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.

B_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.

V_Extended_Flag
Sources which have spatial extents consistent with the point spread function (PSF) of the detector are flagged with FILTER_EXTENDED_FLAG = 0. Sources with measured FWHM major-axes, FILTER_MAJOR_AXIS, greater than the calibrated PSF FWHM with > 3 sigma confidence are flagged with FILTER_EXTENDED_FLAG = 1. Calibrated PSF values for each filter are obtained from the XMM CAL.


Contact Person

Questions regarding the XMMOMSUSS database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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