PMN J1838-3427: A new gravitationally lensed quasar

Joshua N. Winn, Jacqueline N. Hewitt, Paul L. Schechter, Alan Dressler, E. E. Falco, C. D. Impey, C. S. Kochanek, J. Lehár, J. E.J. Lovell, B. A. McLeod, Nicholas D. Morgan, J. A. Muñoz, H. W. Rix, Maria Teresa Ruiz

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We report the discovery of a new double-image quasar that was found during a search for gravitational lenses in the southern sky. Radio source PMN J1838-3427 is composed of two flat-spectrum components with separation I″.0, flux density ratio 14:1, and matching spectral indices in VLA and VLBA images. Ground-based BRI images show the optical counterpart (total I = 18.6) is also double, with the same separation and position angle as the radio components. An HST/WFPC2 image reveals the lens galaxy. The optical flux ratio (27:1) is higher than the radio value, probably because of differential extinction of the components by the lens galaxy. An optical spectrum of the bright component contains quasar emission lines at z = 2.78 and several absorption features, including prominent Lyα absorption. The lens galaxy redshift could not be measured, but it is estimated to be z = 0.36 ± 0.08. The image configuration is consistent with the simplest plausible models for the lens potential. The flat radio spectrum and observed variability of PMN J1838 - 3427 suggest that the time delay between flux variations of the components is measurable and could thus provide an independent measurement of H0.

Original languageEnglish (US)
Pages (from-to)2868-2878
Number of pages11
JournalAstronomical Journal
Issue number6
StatePublished - Dec 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Distance scale
  • Gravitational lensing
  • Quasars: individual (PMN J1838 - 3427)


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