The redshift of the gravitationally lensed radio source PKS 1830-211

C. Lidman, F. Courbin, G. Meylan, T. Broadhurst, B. Frye, W. J.W. Welch

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


We report on the spectroscopic identification and the long-awaited redshift measurement of the heavily obscured, gravitationally lensed radio source PKS 1830-211, which was first observed as a radio Einstein ring. The northeast component of the doubly imaged core is identified, in our infrared spectrum covering the wavelength range 1.5-2.5 μm, as an impressively reddened quasar at z = 2.507 ± 0.002. The mass contained within the Einstein ring radius is M(r < 2.1 h-1 kpc) = 6.3 × 1010 h-1 M⊙ for ΩM = 1 or M(r < 2.4 h-1 kpc) = 7.4 × 1010 h-1 M⊙ for ΩM = 0.3. Our redshift measurement, together with the recently measured time delay (Lovell et al.), means that we are a step closer to determining H0 from this lens. Converting the time delay into H0 by using existing models leads to high values of the Hubble parameter, H0 = 65+15-9 for ΩM = 1 and H0 = 7618-10, for ΩM = 0.3. Since the lensing galaxy lies very close to the center of the lensed ring, improving the error bars on H0 will require not only a more precise time delay measurement but also very precise astrometry of the whole system.

Original languageEnglish (US)
Pages (from-to)L57-L60
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Apr 1 1999


  • Cosmology: observations
  • Gravitational lensing
  • Quasars: individual (PKS 1830-211)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The redshift of the gravitationally lensed radio source PKS 1830-211'. Together they form a unique fingerprint.

Cite this