A Robust Determination of the Time Delay in 0957+561A, B and a Measurement of the Global Value of Hubble's Constant

• DOI: 10.1086/304147
• Publication Date: 2002-07-26T18:48:03Z
• Authors: Tomislav Kundić; Edwin L. Turner; Wesley N. Colley; J. Richard Gott III; James E. Rhoads; Yun Wang; Louis E. Bergeron; Karen A. Gloria; Daniel C. Long; Sangeeta Malhotra; Joachim Wambsganss
• Keywords: 0103 physical sciences; Astrophysics; 01 natural sciences

Continued photometric monitoring of the gravitational lens system 0957+561A, B in g and r bands with Apache Point Observatory (APO) 3.5 m telescope during 1996 shows a sharp g-band event trailing (B) image light curve at precise time predicted an earlier paper. The prediction was based on observation 1995 leading (A) differential delay 415 days. This success confirms so-called short delay, absence any such feature near 540 days rejects "long delay" for this system, thus resolving long-standing controversy. A series statistical analyses our light-curve data yield best-fit 417 ± 3 (95% confidence interval) demonstrate that result is quite robust against variations analysis technique, subsamples, assumed parametric relationship two curves.