V. AllWISE Data Processing

V.3. Multiframe Pipeline Updates

V.3.b Source Extraction

V.3.b.vii. Extended Source Flagging Updates (ext_flg)

The AllWISE Source Catalog and Reject Table contain detections of both point-like and extended sources such as galaxies and nebulae. The ext_flg is used to flag AllWISE sources that are either identified with or superimposed on known galaxies, or have large PSF-fit measurement goodness of fit reduced chi-squared values, a signature of resolved or confused sources. The values of the ext_flg and their descriptions are given in Table 1.

The procedure used to set the ext_flg in AllWISE source extraction is based on that used for the WISE All-Sky Release Catalog, described in section IV.4.c.vi of the WISE All-Sky Release Explanatory Supplement.

Two updates have been implemented for AllWISE:

1. The 2MASS XSC source size scaling has been updated using new measurements of galaxies on the WISE W1 and W2 Atlas Images by Cluver et al. (2014). Figures 1 and 2 show the relationship between the measured WISE isophotal radii and the K_s isophotal radii from the 2MASS XSC, and the relationships used to scale the 2MASS sizes.



Figure 1 - r_W1 vs. r_Ks	Figure 2 - r_W2 vs. r_Ks
Isophotal radii for Galaxies measured on WISE Atlas Images plotted as a function of the Ks isophotal radii from the 2MASS XSC. The red lines show the best-fit linear scaling relationships between the WISE and 2MASS sizes (Cluver et al. 2014).



2. The diameter of 2MASS XSC sources that were cross-matched with the AllWISE extractions was reduced to 14 arsec, down from the 25 arcsec that was used for the WISE All-Sky Source Catalog flagging. This expanded the list of galaxies considered to 572,332 from the previous 180,819.