1998A&A...331..853C

To date, the quasar 1556+3517 is the only radio loud Broad Absorption Line QSO (BALQSO; Becker et al., 1997ApJ...479L..93B). This prompted narrow band filter imaging observations in the range 4-15µ with the ISO satellite. The source is clearly detected in all filters and appears point-like and isolated at the resolution of ISO. The overall Spectral Energy Distribution (SED) in erg/s peaks at a rest wavelength ≥6µ and is reddened by 1.6 visual magnitudes. Correction for reddening brings 1556+3517 within 1.3σ from the logR=1 dividing line between radio-loud and radio-quiet sources. The mid-IR luminosity integrated over the 1.8-6µ rest wavelength range is ∼2x10⁴⁶erg/s (H₀=75km/s/Mpc, q₀=0), which requires at least 4M_☉ of dust and 800M_☉ of associated gas. It is unlikely that such a large mass stems from the BAL wind itself.