| Abstract | An investigation was made of the neutral hydrogen content of nine Sb and Sc galaxies, with redshifts in the range 1545 to 2620 km s-1. Eight of these galaxies have high intrinsic luminosities (L> 19 X io9L0). The observations were made at Jodrell Bank with the Mark I in two pencil-beain studies using bandwidths of 34 and 18 kllz. All the galaxies were smaller than the beamwidth of the Mark I telescope. Some of the galaxies were observed with the Mark I -Mark II interferometer using a 100 kllz bandwidth. Four of the galaxies, NGC 772, 2776, 4303, and s668, produced intense enough signals when observed with the Mark I telescope to give an integrated spectrum from which the neutral hydrogen content, the total mass and the systemic velocity could be estimated NGC. 2776 was the only galaxy in which neutral hydrogen was detected with the interferometer. A continuum source with a diameter of the optical diameter was found at the centre of NGC 972. The measured systemic velocity of NGC 2776 is 2620+ 10 km -1, the highest velocity detected so far at 21 cm. Optical and 21-cm velocity measurements of external galaxies are now available for a total velocity range of 2967 km 1 and indicate that the cosmological redshift is the same to within I per cent over a wavelength range of 5 x i o : I. |
