2006ApJ...640L.127B

The Westerbork Synthesis Radio Telescope finds a weak 21 cm line emission feature at the coordinates (R.A., decl., velocity) of the sub-damped Lyα (DLA) absorber observed at z_abs=0.00632 in the spectrum of PG 1216+069. The emission feature, WSRT J121921+0639, lies within 30" of the quasar sight line, is detected at a 99.8% (3 σ) confidence level, has M_HI_ between 5 and 15x10⁶ M_☉, and has a velocity spread between 20 and 60 km/s. Other H I emitters in the field include VCC 297 at a projected distance of 86 h^–1₇₅kpc and a previously unreported H I cloud, WSRT J121919+0624, at 112 h^–1₇₅kpc with M_HI_∼3x10⁸ M_☉. The optically identified foreground galaxy that is closest to the quasar sight line appears to be VCC 339 (∼L^*/25) at 29 h^–1₇₅kpc with a velocity offset of 292 km/s. A low surface brightness galaxy with the H I mass of the sub-DLA absorber WSRT J121921+0639 would likely have m_B∼17, and its diffuse optical emission would need to compete with the light of both the background QSO and a brighter foreground star ∼10" from the QSO sight line.