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The comparison between the WMAP and 3EG cat- alogs produced 69 matches out of the 390 WMAP and 138 EGRET sources outside the WMAP Galactic mask. The number expected randomly is 20; the prob- ability of having 69 matches among the 390 WMAP sources is P < ∼ 10 − $^{17}$, indicating that most -but not all- the matches are real. 

When accounting for the source type we count 40 matches out of the 54 high confidence blazar associa- tion, labelled A in the 3EG catalog, compared to 6.6 expected randomly. The low confidence ”a” associa- tions have 17 matches out of 23 tries and 3.3 expected chance coincidences. On the other hand we have 11 matches among the 61 unidentified sources out of the WMAP mask, expecting 10.0 by chance. On statisti- cal grounds, we can confirm the physical association of foreground WMAP sources with 3EG blazars, ac- counted by both ”A” and ”a” classes, but not with unidentified EGRET sources (table I). 

We also compared the WMAP positions with the list of very high energy (VHE) photons, E > 10 GeV [7]: 510 out of the 1506 VHE photons are outside the WMAP Galactic mask. The combined po- sitional accuracy of VHE photons and WMAP sources is 30 . 2 $^{′}$. We obtained coincidences between 33 VHE photons and 29 WMAP sources as follows: 

## A. Matching WMAP with EGRET 

– 20 WMAP sources coincide with a single isolated VHE photon; 

– 4 WMAP sources coincide with a single VHE pho- ton and a 3EG, with no 0FGL counterpart; 

– 1 WMAP source (WMAP J1408–0749) coincides with a 3EG source (3EG J1409–0745) and 4 VHE photons (VHE 494, 498, 1058 and 1061) – but with no 0FGL counterpart: 

– 3 WMAP sources coincide with VHE photons, 3EG and 0FGL sources; of these WMAP J0210-5100 has two VHE photons; 

– 1 WMAP source (WMAP J0137+4753) coin- cides with a VHE photon and a 0FGLsource (0FGL 0137.1+4751), with no 3EG counterpart. 

We note that given the number and error box sizes of the VHE photons, we expect 30 random matches under our 2.5 σ criterion. Most or all of the single WMAP -VHE coincidences are likely to be spurious. We note the case of WMAP J0137+4753, which be- longed to the WMAP & VHE only category prior to the publication of the 0FGL and turned out to be a real γ -ray source. 

