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NGC300CXO - NGC 300 Chandra X-Ray Point Source Catalog

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Overview

This table contains the source catalog from a new Chandra ACIS-I observation of the nearby (2.0 Mpc) SA(s)d spiral galaxy NGC 300 which was obtained as part of the Chandra Local Volume Survey (CLVS). This 63-ks exposure covers ~88% of the D25 isophote (R ~ 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance down to a limiting unabsorbed 0.35-8 keV luminosity of ~ 1036 erg/s. Sources were cross-correlated with a previous XMM-Newton catalog, and the authors find 75 "X-ray transient candidate" sources that were detected by one observatory, but not the other. They derive an X-ray scale length of 1.7 +/- 0.2 kpc and a recent star formation rate of 0.12 Msun/yr in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering ~ 32% of this Chandra field, was used to search for optical counterparts to the X-ray sources, and the authors have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background active galactic nucleus candidates. In the reference paper, the authors present the X-ray luminosity functions (XLFs) at different X-ray energies, and find the total NGC 300 X-ray point-source population to be consistent with other late-type galaxies hosting young stellar populations (<~ 50 Myr). They find that the XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions.

NGC 300 was observed on 2010 September 25 for 63 ks using ACIS-I during the Chandra X-Ray Observatory Cycle 12, observation ID 12238. The source detection strategy that was used is described in Section 2.3 of the reference paper. ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 and 0.35 - 8.0 keV. To be included in the final NGC 300 catalog, a source was required to have a pns value less than 4 x 10-6 in any of the nine energy bands; if only the 0.35 - 8 keV band were considered, ~4% of significant sources would have been lost. The final CLVS source catalog for NGC 300 contains 95 sources.


Catalog Bibcodes

2012ApJ...758...15B
2015AJ....150...94B

References

The Chandra Local Volume Survey: the X-ray point-source catalog of NGC 300.
    Binder B., Williams B.F., Eracleous M., Gaetz T.J., Plucinsky P.P.,
    Skillman E.D., Dalcanton J.J., Anderson S.F., Weisz D.R., Kong A.K.H.
   <Astrophys. J., 758, 15 (2012)>
   =2012ApJ...758...15B

The Chandra Local Volume Survey. I. The X-ray point-source populations of
NGC 55, NGC 2403, and NGC4214.
    Binder B., Williams B.F., Eracleous M., Plucinsky P.P., Gaetz T.J.,
    Anderson S.F., Skillman E.D., Dalcanton J.J., Kong A.K.H., Weisz D.R.
   <Astron. J., 150, 94 (2015)>
   =2015AJ....150...94B

Provenance

This table was initially created by the HEASARC in September 2014 based on CDS Catalog J/ApJ/758/15/ files table4.dat, table5.dat, table6.dat and table7.dat containing the X-ray properties of the 95 Chandra point sources found in this study. The information on the optical counterparts to (some of) the Chandra X-ray sources and on the X-ray point source classification (presented in Tables 16 and 17, respectively, of the reference paper) is not included herein. It was updated in September 2015 to include the unabsorbed 0.35-8.0 keV energy fluxes (in the parameter herein called b4_flux) from the second reference paper.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension.

Name
The name of the X-ray source using the 'CXOLV' prefix (for Chandra X-ray Observatory Local Volume Survey source) and the J2000.0 coordinates of the source in the (higher precision than standard) HHMMSS.ss+DDMMSS.s format.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 decimal degree coordinates and to a precision of 10-6 degrees in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The positional uncertainty of the X-ray source, being the radius of a simple error circle around the source position, in arcseconds.

Mean_Expo_Map_Value
The sum of the mean exposure map values in the X-ray source region, in s cm-2.

Extraction_Radius
The average radius of the source extraction region, in sky pixels, where 1 sky pixel = 0.392 arcseconds.

Off_Axis
The off-axis angle of the X-ray source, in arcminutes.

B1_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B1_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 0.5 - 8 keV band. Values smaller than -10 have been replaced by "<-10".

B2_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B2_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 0.5 - 2 keV band. Values smaller than -10 have been replaced by "<-10".

B3_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B3_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 2 - 8 keV band. Values smaller than -10 have been replaced by "<-10".

B4_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B4_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 0.35 - 8 keV band. Values smaller than -10 have been replaced by "<-10".

B5_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B5_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 0.35 - 1.1 keV band. Values smaller than -10 have been replaced by "<-10".

B6_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B6_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 1.1 - 2.6 keV band. Values smaller than -10 have been replaced by "<-10".

B7_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B7_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 2.6 - 8 keV band. Values smaller than -10 have been replaced by "<-10".

B8_Log_Prob_NS_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B8_Log_Prob_NS
The logarithm of the Poisson probability of not being a source (log prob_no_source or log pns) in the 0.35 - 2 keV band. Values smaller than -10 have been replaced by "<-10".

B1_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B1_Counts
The total net counts in the X-ray source in the 0.5 - 8 keV band.

B1_Counts_Pos_Err
The upper uncertainty in the 0.5 - 8 keV band of the net source counts.

B1_Counts_Neg_Err
The lower uncertainty in the 0.5 - 8 keV band of the net source counts.

B2_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B2_Counts
The total net counts in the X-ray source in the 0.5 - 2 keV band.

B2_Counts_Pos_Err
The upper uncertainty in the 0.5 - 2 keV band of the net source counts.

B2_Counts_Neg_Err
The lower uncertainty in the 0.5 - 2 keV band of the net source counts.

B3_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B3_Counts
The total net counts in the X-ray source in the 2 - 8 keV band.

B3_Counts_Pos_Err
The upper uncertainty in the 2 - 8 keV band of the net source counts.

B3_Counts_Neg_Err
The lower uncertainty in the 2 - 8 keV band of the net source counts.

B4_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B4_Counts
The total net counts in the X-ray source in the 0.35 - 8 keV band.

B4_Counts_Pos_Err
The upper uncertainty in the 0.35 - 8 keV band of the net source counts.

B4_Counts_Neg_Err
The lower uncertainty in the 0.35 - 8 keV band of the net source counts.

B5_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B5_Counts
The total net counts in the X-ray source in the 0.35 - 1.1 keV band.

B5_Counts_Pos_Err
The upper uncertainty in the 0.35 - 1.1 keV band of the net source counts.

B5_Counts_Neg_Err
The lower uncertainty in the 0.35 - 1.1 keV band of the net source counts.

B6_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B6_Counts
The total net counts in the X-ray source in the 1.1 - 2.6 keV band.

B6_Counts_Pos_Err
The upper uncertainty in the 1.1 - 2.6 keV band of the net source counts.

B6_Counts_Neg_Err
The lower uncertainty in the 1.1 - 2.6 keV band of the net source counts.

B7_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B7_Counts
The total net counts in the X-ray source in the 2.6 - 8 keV band.

B7_Counts_Pos_Err
The upper uncertainty in the 2.6 - 8 keV band of the net source counts.

B7_Counts_Neg_Err
The lower uncertainty in the 2.6 - 8 keV band of the net source counts.

B8_Counts_Limit
This limit parameter is set to '<' if the corresponding parameter value is an upper limit rather than an actual value.

B8_Counts
The total net counts in the X-ray source in the 0.35 - 2 keV band.

B8_Counts_Pos_Err
The upper uncertainty in the 0.35 - 2 keV band of the net source counts.

B8_Counts_Neg_Err
The lower uncertainty in the 0.35 - 2 keV band of the net source counts.

B1_Log_Photon_Flux
The logarithm of the 0.5 - 8 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B2_Log_Photon_Flux
The logarithm of the 0.5 - 2 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B3_Log_Photon_Flux
The logarithm of the 2 - 8 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B4_Log_Photon_Flux
The logarithm of the 0.35 - 8 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B5_Log_Photon_Flux
The logarithm of the 0.35 - 1.1 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B6_Log_Photon_Flux
The logarithm of the 1.1 - 2.6 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B7_Log_Photon_Flux
The logarithm of the 2.6 - 8 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B8_Log_Photon_Flux
The logarithm of the 0.35 - 2 keV band photon flux, in photons cm-2 S-1, provided by AE and based on the net number of source counts, the exposure time and the mean ARF in the given energy band.

B4_Flux
This parameter contains the unabsorbed X-ray flux in the 0.35-8 keV energy band, in erg cm-2 s-1. For one source (number 60), the value is negative (-4.0e-16), presumably meaning that the quoted value is an upper limit rarther than a detection in this band.


Contact Person

Questions regarding the NGC300CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 24-Sep-2015