Fifth image and photometric variability in 2237 + 0305 ('Einstein Cross')

CCD frames in R and I obtained with HRCam at the CFHT in 0.4" (FWHM) seeing on 1990 August 23.3 U.T. were combined to produce S/N > 500 images at 0.13" /pixel sampling of the brighter components of the quasar gravitationally lensed by 2237+0305. Relative magnitudes (+/-<0.01 mag), positions (+/- <0.002") and angular sizes are derived for the four previously known quasar images and for the core of the lensing galaxy. Compared with Yee's [AJ, 95,1331 (1988)] photometry, these data show components B brighter by 0.25 mag and C fainter by 0.15 mag while the brightness of A and D and the colors of all four images are unchanged. The general variability of all four components between 1986 and 1990 is discussed. The intrinsic dispersions of the intensity profiles are σ < 0.08" for the quasar images and σ= 0.21"x0.15"+/-0.05" (FWHM = 0.50"x0.35") in P.A. = 83^deg^=/- 2^deg^ for the galaxy core. Subtraction of these components leaves a fifth stellar image 4.5+/-0.3 mag fainter than component A and 0.07"+/- 0.035" SSE of the lensing galaxy center.

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