H I 21 cm observations of the PG 1216+069 sub-damped Lyα absorber field at z=0.00632

The Westerbork Synthesis Radio Telescope finds a weak 21 cm line emission feature at the coordinates ( R. A., decl., velocity) of the sub-damped Ly alpha (DLA) absorber observed at in the spectrum of PG z(abs) = 0.00632 1216+069. The emission feature, WSRT J121921 + 0639, lies within 30 double prime of the quasar sight line, is detected at a 99.8% (3 sigma) confidence level, has M-H I between 5 and 15 x 10(6) M-circle dot, and has a velocity spread between 20 and 60 km s(-1). Other H I emitters in the field include VCC 297 at a projected distance of 86 h(75)(-1) kpc and a previously unreported H I cloud, WSRT J121919 + 0624, at 112h(75)(-1) kpc with M-H I similar to 3 x 10(8) M-circle dot. The optically identified foreground galaxy that is closest to the quasar sight line appears to be VCC 339 (similar to L*/25) at 29 h(75)(-1) kpc with a velocity offset of 292 km s(-1). A low surface brightness galaxy with the H I mass of the sub-DLA absorber WSRT J121921 + 0639 would likely have m(B) similar to 17 and its diffuse optical emission would need to compete with the light of both the background QSO and a brighter foreground star similar to 10 double prime from the QSO sight line.