A new quadruple gravitational lens system: CLASS B0128+437

Phillips, PM., Norbury, MA., Koopmans, LVE., Browne, IWA., Jackson, NJ., Wilkinson, PN., Biggs, AD., Blandford, RD., de Bruyn, AG., Fassnacht, CD., Helbig, P., Mao, S., Marlow, DR., Myers, ST., Pearson, TJ., Readhead, ACS., Rusin, D. & Xanthopoulos, E., 1-Dec-2000, In : Monthly Notices of the Royal Astronomical Society. 319, 2, p. L7-L11 5 p.

Research output: Contribution to journalArticleAcademicpeer-review

  • PM Phillips
  • MA Norbury
  • LVE Koopmans
  • IWA Browne
  • NJ Jackson
  • PN Wilkinson
  • AD Biggs
  • RD Blandford
  • AG de Bruyn
  • CD Fassnacht
  • P Helbig
  • S Mao
  • DR Marlow
  • ST Myers
  • TJ Pearson
  • ACS Readhead
  • D Rusin
  • E Xanthopoulos

High-resolution MERLIN observations of a newly discovered four-image gravitational lens system, B0128+437, are presented. The system was found after a careful re-analysis of the entire CLASS data set. The MERLIN observations resolve four components in a characteristic quadruple-image configuration; the maximum image separation is 542 mas and the total flux density is 48 mJy at 5 GHz. A best-fitting lens model with a singular isothermal ellipsoid results in large errors in the image positions. A significantly improved fit is obtained after the addition of a shear component, suggesting that the lensing system is more complex and may consist of multiple deflectors. The integrated radio spectrum of the background source indicates that it is a gigahertz peaked spectrum source, It may therefore be possible to resolve structure within the radio images with deep VLBI observations and thus to constrain the lensing mass distribution better.

Original languageEnglish
Pages (from-to)L7-L11
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1-Dec-2000


  • quasars : individual : B0128+437, cosmology : observations, gravitational lensing, PHASE CALIBRATION SOURCES, VLA ASTROMETRIC SURVEY, RADIO-SOURCES, SKY SURVEY, STATISTICS

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