Shock-excited molecular hydrogen in the southern shell of the HB 3 SNR (see Figure 5 and the exact location is marked as a white box). Palomar WIRC narrow-band image (a) and Spitzer 4.5 μm (b) and 3.6 μm (c) images centered on R.A. 2^h17^m46.7ˢ and decl. +61°52′34.1″ (J2000) with an FOV of 8.8′ × 8.4′. The diffuse emission in the WIRC H₂ 2.12 μm image ranges 0.179–1.3 MJy sr⁻¹ (∼1.91–13.9 × 10⁻⁶ erg s⁻¹ cm⁻² sr⁻¹). The emission in the Spitzer 4.5 and 3.6 μm images ranges 0.3–1.4 (typical background is 0.2) MJy sr⁻¹ and 0.44–0.83 (0.35) MJy sr⁻¹, respectively. The filament positions of D and E (see Table 4) are marked on the image (b).