WMAPCMBFPS - WMAP Nine-Year CMB-Free QVW Point Source Catalog
The CMB-free method of point source identification was originally applied to one-year and three-year V- and W-band maps by Chen & Wright (2008, ApJ, 681, 747) and to five-year V- and W-band maps by Wright et al. (2009, ApJS, 180, 283). The method used here is that applied to five-year Q-, V-, and W-band maps by Chen & Wright (2009, ApJ, 694, 222) and to seven-year Q-, V-, and W-band maps by Gold et al. (2011, ApJS, 192, 15). The V- and W-band maps are smoothed to Q-band resolution. An internal linear combination (ILC) map (see Section 5.3.3 of the reference paper) is then formed from the three maps using weights such that CMB fluctuations are removed, flat-spectrum point sources are retained with fluxes normalized to Q-band, and the variance of the ILC map is minimized. The ILC map is filtered to reduce noise and suppress large angular scale structure. Peaks in the filtered map that are > 5 sigma and outside of the nine-year point source catalog mask are identified as point sources, and source positions are obtained by fitting the beam profile plus a baseline to the filtered map for each source. For the nine- year analysis, the position of the brightest pixel is adopted instead of the fit position in rare instances where they differ by > 0.1 degrees. Source fluxes are estimated by integrating the Q, V, and W temperature maps within 1.25 degrees of each source position, with a weighting function to enhance the contrast of the point source relative to background fluctuations, and applying a correction for Eddington bias due to noise (sometimes called "deboosting").
The authors identify possible 5-GHz counterparts to the WMAP sources found by cross-correlating with the GB6 (Gregory et al. 1996, ApJS, 103, 427), PMN (Griffith et al. 1994, ApJS, 90, 179; Griffith et al. 1995, ApJS, 97, 347; Wright et al. 1994, ApJS, 94, 111; Wright et al. 1996, ApJS, 103, 145), Kuehr et al. (1981, A&AS, 45, 367), and Healey et al. (2009, AJ, 138, 1032) catalogs. A 5-GHz source is identified as a counterpart if it lies within 11 arcminutes of the WMAP source position (the mean WMAP source position uncertainty is 4 arcminutes). When two or more 5 GHz sources are within 11 arcminutes, the brightest is assumed to be the counterpart and a multiple identification flag is entered in the catalog.
A separate 9-year Point Source Catalog (available in Browse as the WMAPPTSRC table) has information on 501 point sources in five frequency bands from 23 to 94 GHz that were found using an alternative method. The two catalogs have 387 sources in common. As noted by Gold et al. (2011, ApJS, 192, 15), differences in the source populations detected by the two search methods are largely caused by Eddington bias in the five-band source detections due to CMB fluctuations and noise. At low flux levels, the five-band method tends to detect point sources located on positive CMB fluctuations and to overestimate their fluxes, and it tends to miss sources located in negative CMB fluctuations. Other point source detection methods have been applied to WMAP data and have identified sources not found by our methods (e.g., Scodeller et al. (2012, ApJ, 753, 27); Lanz (2012, ADASS 7); Ramos et al. (2011, A&A, 528, A75), and references therein).
For more details of how the point source catalogs were constructed, see Section 5.2.2 of the reference paper.
Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results Bennett C.L., Larson D., Weiland J.L., Jarosik N., Hinshaw G., Odegard N., Smith K.M., Hill R.S., Gold B., Halpern M., Komatsu E., Nolta M.R., Page L., Spergel D.N., Wollack E., Dunkley J., Kogut A., Limon M., Meyer S.S., Tucker G.S., Wright, E.L. <Astrophys. J. Suppl., submitted)> =2012arXiv1212.5225B
The name of the point source using the prefix 'WMAP QVW' and the J2000.0 equatorial source coordinates, e.g., 'WMAP QVW JHHMM+DDMM'. The HEASARC has added the 'QVW' to differentiate these sources from those in the WMAP Point Source Catalog (the HEASARC WMAPPTSRC table) which have names of the form 'WMAP JHHMM+DDMM'.
The Right Ascension of the WMAP source in the selected equinox. The RA was given in J2000.0 coordinates to a precision of 0.1 seconds in the original table.
The Declination of the WMAP source in the selected equinox. The Declination was given in J2000.0 coordinates to a precision of 1 arcsecond in the original table
The Galactic Longitude of the WMAP source.
The Galactic Latitude of the WMAP source.
The Q-band (41 GHz) flux density of the WMAP source, in mJy. The flux densities were specified to a precision of 0.1 Jy (100 mJy) in the original table.
The uncertainty in the Q-band (41 GHz) flux density of the WMAP source, in mJy.
The V-band (61 GHz) flux density of the WMAP source, in mJy. The flux densities were specified to a precision of 0.1 Jy (100 mJy) in the original table.
The uncertainty in the V-band (61 GHz) flux density of the WMAP source, in mJy.
The W-band (94 GHz) flux density of the WMAP source, in mJy. The flux densities were specified to a precision of 0.1 Jy (100 mJy) in the original table.
The uncertainty in the W-band (94 GHz) flux density of the WMAP source, in mJy.
The name of the corresponding 5-GHz source, if there is such a source within 11 arcminutes of this position, found from correlating against the GB6, PMN and Kuehr et al. (1981, A&AS, 45, 367) catalogs (the HEASARC Browse tables GB6, PMN and KUEHR, respectively). Sources from the Kuehr Catalog have a '1Jy' prefix, notice. When a 5-GHz source identification is not available, the name of the closest NVSS 1.4-GHz source is given.
This parameter may contain a flag with the following meaning:
a = Indicates this source has multiple possible identifications. When two or more 5-GHz sources are within 11 arcminutes, the brightest is assumed to be the counterpart and the multiple identification flag is entered in the catalog.
The First Year Catalog source identification number. In the first-year catalog, source ID numbers were assigned on the basis of position (sorted by galactic longitude). Now, rather than assigning new numbers to the newly detected sources, the authors recommend that WMAP sources be referred to by their position-based names (see above), but, for reference, the first-year source ID is given in this parameter.