BMWCHANCAT - Brera Multi-scale Wavelet Chandra Source Catalog

Overview

This table contains the BMW-Chandra source catalog drawn from essentially all Chandra ACIS-I pointed observations with an exposure time in excess of 10 ks that were public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by Lazzati et al. (1999ApJ...524..414) and Campana et al. (1999ApJ...524..423C), which can characterize both point-like and extended sources, the authors identified 21325 sources. Among them, 16758 are serendipitous, i.e. not associated with the targets of the pointings, and do not require a non-automated analysis. This makes this catalog the largest compilation of Chandra sources as of the date of publication of this catalog (August 2008). The 0.5 - 10 keV absorption corrected fluxes of these sources range from ~3 x 10^-16 to 9 x 10^-12 erg/cm²/s with a median of 7 x 10^-15 erg/cm²/s.

The catalog consists of count rates and relative errors in three energy bands (total, 0.5 - 7 keV; soft, 0.5 - 2 keV; and hard, 2 - 7 keV), and source positions relative to the highest signal-to-noise detection among the three bands. The wavelet algorithm also provides an estimate of the extension of the source. The authors include information drawn from the headers of the original files, as well, and extracted source counts in four additional energy bands, SB1 (0.5 - 1 keV), SB2 (1 - 2 keV), HB1 (2 - 4 keV), and HB2 (4 - 7 keV). They computed the sky coverage for the full catalog and for a subset at high Galactic latitude (|b| > 20 degrees). The complete catalog provides a sky coverage in the soft band (0.5 - 2 keV, S/N = 3) of ~8 deg² at a limiting flux of 10^-13 erg/cm²/s, and ~2 deg² at a limiting flux of ~10^-15 erg/cm²/s. The total numbers of matches with the FIRST, IRASPSC, 2MASS, and GSC2 catalogs obtained after a closest-distance selection are 13, 87, 6700, and 4485, respectively.

Catalog Bibcode

2008A&A...488.1221R

References

The Brera Multi-scale Wavelet Chandra Survey. I.
Serendipitous source catalogue.
    Romano P., Campana  S., Mignani R.P., Moretti A., Mottini M., Panzera M.R.,
    Tagliaferri G.
    <Astron. Astrophys. 488, 1221 (2008)>
    =2008A&A...488.1221R        (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in September 2008 based on the CDS table J/A+A/488/1221 file catalog.dat. The catalog version is BMC 1.0.1F. All sources in this version of the catalog were from observations in POINTING and TIMED ACIS read modes.

Parameters

Source_Number
A running number for the X-ray source which uniquely identifies it, and is mostly used as an internal reference.

Name
The IAU-style X-ray source designation using the '1BMC' prefix for 'Brera Multi-scale wavelet Chandra, Version 1' and the truncated J2000.0 equatorial coordinates (JHHMMSS.s+DDMMSS), as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Sequence_Number
The Chandra observation sequence number in which the source was detected.

Field_Target
The designated target for the Chandra observation in which the source was detected.

ObsID
The Chandra observation ID number in which the source was detected.

Nominal_Exposure
The nominal total exposure time, in seconds (s), of the observation in which the source was detected.

Frame_Time
The commanded exposure time, i.e., the frame time, in seconds (s), of the observation in which the source was detected.

Ascds_Version
The ASCDS (AXAF Science Center Data analysis System) Version Number.

Time
The date and time of the start of the observation.

End_Time
The date and time of the end of the observation.

Field_Target_RA_J2000
The Right Ascension (in J2000 sexagesimal coordinates) of the nominal target of the Chandra observation.

Field_Target_Dec_J2000
The Declination (in J2000 sexagesimal coordinates) of the nominal target of the Chandra observation.

Data_Mode
The Chandra ACIS data mode: RAW, FAINT, FAINT_BIAS, VFAINT, GRADED, CC33_FAINT, or CC33_GRADED.

Exposure
The effective exposure time of the source, in seconds (s), i.e., the exposure after flares have been removed.

Bck_Counts
The total-band (0.5 - 7.0 keV) mean background counts per pixel in the central 1024 x 1024 pixel region.

Bck_SB_Counts
The soft-band (05 - 2.0 keV) mean background counts per pixel in the central 1024 x 1024 pixel region.

Bck_HB_Counts
The hard-band (2.0 - 7.0 keV) mean background counts per pixel in the central 1024 x 1024 pixel region.

Field_Target_NH
The weighted averaged line-of-sight Galactic column density N_H (in H atoms cm^-2) in the direction of the nominal target of the Chandra observation.

Flux_Cr_Corfac
The conversion factor CORFAC1 in erg/cm²/ct used to translate the model 0.5 - 7.0 keV count rate of the source to the estimated 0.5 - 10 keV source flux in erg/s/cm² (given in the full_band_flux parameter) assuming as input model an absorbed (wabs) power law model with a photon index of 2.0 (i.e., a Crab spectrum, for direct comparison with other work) and the Galactic column density, where the flux is calculated as: FLUX1 = COR_FAC1 x T_FT_CTS / EXPOSURE, where T_FT_CTS are the WT total counts and EXPOSURE is the total exposure time.

RA
The Right Ascension of the source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.001 seconds of time in the original table.

Dec
The Declination of the source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 arcseconds in the original table.

LII
The Galactic Longitude of the source.

BII
The Galactic Latitude of the source.

RA_Error
The uncertainty in the source Right Ascension, in arcseconds.

Dec_Error
The uncertainty in the source Declination,in arcseconds.

Error_Radius
The total positional uncertainty, in arcseconds.

Wt_Width
The width of the wavelet transform (WT) Gaussian distribution of photons, in arcseconds.

Wt_Width_Error
The uncertainty in the width of the WT Gaussian distribution of photons, in arcseconds.

Wt_Width_Flag
The meaningfulness of the WT width, where 0 = free while 1 = fixed to PSF.

Src_Wt_Scale
The WT scale at which the source was found. Seven WT scales (1, 2, 4, 8, 16, 32 and 64 pixels) were used to cover a wide range of source sizes.

Chi_Squared
The chi-squared of the fit to the source with respect to a Gaussian model source in the WT space.

Off_Axis
The off-axis angle of the source from the nominal ACIS pointing direction, in arcminutes.

X_Pixel
The source X coordinate, in pixels, in detector space.

Y_Pixel
The source Y coordinate, in pixels, in detector space.

Counts
The total-band (0.5 - 7 keV) source counts from the fit.

Counts_Error
The uncertainty in the total-band source counts from the fit.

Counted_Counts
The total-band net 'counted' source counts.

Counted_Bck_Counts
The total-band counted background counts.

Vignetting_Factor
The total-band vignetting correction factor for the source.

PSF_Corr_Factor
The total-band PSF correction factor for the source.

Count_Rate
The total-band count rate for the source, in ct/s.

Count_Rate_Error
The uncertainty in the total-band count rate for the source, in ct/s.

Flux
The total-band flux of the source, in erg/s/cm², calculated from the total-band count rate using a fixed conversion factor COR_FAC0 of 1.0E-11 erg/cm²/ct.

SNR
The total-band signal-to-noise ratio (SNR) of the source detection.

Wavelet_SNR
The total-band SNR in wavelet space for the source.

SB_Counts
The soft-band (0.5 - 2 keV) source counts from the fit.

SB_Counts_Error
The uncertainty in the soft-band source counts from the fit.

SB_Counted_Counts
The soft-band net 'counted' source counts

SB_Counted_Bck_Counts
The soft-band counted background counts

SB_Vignetting_Factor
The soft-band vignetting correction factor for the source.

SB_PSF_Corr_Factor
The soft-band PSF correction factor for the source.

SB_Count_Rate
The soft-band count rate for the source, in ct/s.

SB_Count_Rate_Error
The uncertainty in the soft-band count rate for the source, in ct/s.

SB_Flux
The soft-band flux of the source, in erg/s/cm², calculated from the soft-band count rate using a fixed conversion factor COR_FAC0 of 1.0E-11 erg/cm²/ct.

SB_SNR
The soft-band signal-to-noise ratio (SNR) of the source detection

SB_Wavelet_SNR
The soft-band SNR in wavelet space for the source.

HB_Counts
The hard-band (2 - 7 keV) source counts from the fit.

HB_Counts_Error
The uncertainty in the hard-band source counts from the fit.

HB_Counted_Counts
The hard-band net 'counted' source counts

HB_Counted_Bck_Counts
The hard-band counted background counts

HB_Vignetting_Factor
The hard-band vignetting correction factor for the source.

HB_PSF_Corr_Factor
The hard-band PSF correction factor for the source.

HB_Count_Rate
The hard-band count rate for the source, in ct/s.

HB_Count_Rate_Error
The uncertainty in the hard-band count rate for the source, in ct/s.

HB_Flux
The hard-band flux of the source, in erg/s/cm², calculated from the hard-band count rate using a fixed conversion factor COR_FAC0 of 1.0E-11 erg/cm²/ct.

HB_SNR
The hard-band signal-to-noise ratio (SNR) of the source detection

HB_Wavelet_SNR
The hard-band SNR in wavelet space for the source.

Rebin_Number
The rebin at which the source was found, i.e., 1 or 2.

Wt_Probability
The WT probability of the source, WTPROBAB. The wavelet probability is defined as the confidence level at which a source is not a chance background fluctuation, given the background statistics and the specific field exposure time. This quantity is assessed via the S/N ratio in WT space. For each WT scale, the noise level is computed through numerical simulations of blank fields with the corresponding background, while the signal is the peak of the WT coefficients corresponding to the source. In order to make this significance more easily comparable to other methods, confidence intervals are approximately expressed in units of the standard deviation (sigma) for which a Gaussian distributed variable would give an equal probability of spurious detection (68%: 1 sigma; 95%: 2 sigma, etc.). So, the values of the wavelet probability in WTPROBAB represent the number of sigmas corresponding to the confidence level of that specific source.

Full_Band_Flux
The absorption-corrected 0.5 - 10 keV flux of the source, in erg/s/cm². The conversion factor CORFAC1 (the parameter flux_cr_corfac in this table), in erg/cm²/ct, was used to translate the model 0.5 - 7.0 keV count rate of the source to the estimated 0.5 - 10 keV source flux in erg/s/cm² (given in this parameter), assuming as input model an absorbed (wabs) power-law model with a photon index of 2.0 (i.e., a Crab spectrum, for direct comparison with other work) and the Galactic column density, where the flux is calculated as: COR_FAC1 x T_FT_CTS / EXPOSURE, where T_FT_CTS are the WT total counts and EXPOSURE is the total exposure time.

Full_Band_Obs_Flux
The observed full-band (0.5 - 0 keV) flux of the source, in erg/s/cm², calculated using a conversion factor of 8.23E-12 erg/cm²/ct appropriate for an unabsorbed Crab spectrum.

Quality_Flag_1
The first quality flag for the source, where 1 means that the status is 'OK', whereas values <-1 indicate decreasing quality.

Quality_Flag_2
The second quality flag for the source, where -1 indicates the source should be visually inspected, values < -1 indicate decreasing quality, and the values for sources within a radius of 30 arcseconds from the target position of the Chandra pointing (for all fields not in surveys) have been multiplied by 10.

Extent_Flag
This flag indicates whether the source is consistent with being point-like or extended (POINT/EXTENDED).

Cross_Match_Flag_1
This flag indicates whether this source has a match in the merged catalog within a cross-matching radius of 3.0 arcseconds, where 1 means yes, and 0 means no.

Cross_Match_Flag_2
This flag indicates whether this source has a match in the merged catalog within a cross-matching radius of 4.5 arcseconds, where 1 means yes, and 0 means no.

Counted_Band1_Counts
The counted source counts in the 0.5 - 1.0 keV energy band.

Counted_Band2_Counts
The counted source counts in the 1.0 - 2.0 keV energy band.

Counted_Band3_Counts
The counted source counts in the 2 - 4 keV energy band.

Counted_Band4_Counts
The counted source counts in the 4 - 7 keV energy band.

Contact Person

Questions regarding the BMWCHANCAT database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:25:06 EDT