VSOP observations of extremely distant quasars.

 

[a project in collaboration with L.Gurvits, R.T. Schilizzi (JIVE), S.Frey (FOMI SGO), K.I.Kellermann (NRAO), N.Kawaguchi(NAO), & I.I.K.Pauliny-Toth(MPIfR)]

 

2215+020 (z=3.58, S_1.4GHz=0.8Jy) is included in the sample of high-redshift quasars to be observed with VSOP. No prior VLBI observations of this object are known to us.  A VSOP observation at 1.6GHz was made on September 14 1997.  15 ground telescopes and 2 satellite data acquisition stations participated in the observations. The data were correlated at the NRAO correlator in Socorro. Subsequent fringe fitting was done in AIPS; imaging and self-calibration were performed using DIFMAP.  Shown below are an image obtained using only the baselines provided by the ground telescopes, and a full-resolution VSOP image of the source.The linear scale in the images is 6.8 pc/mas, for H₀=50 km/(s Mpc) and q₀=0.5.

Both images are made from uniformly weigthed visibility data.

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Ground VLBI image of 2215+020 at 1.6 GHz

(contour plot,  visibility plot, uv-plot).

 

 

Image characteristics:  Thermal noise: 0.08 mJy.    Self-calibration noise: 0.16 mJy.

Total CLEAN flux: 451.3mJy.   Map minimum: -1.8 mJy.

  

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VSOP image of 2215+020 at 1.6GHz

(contour plot, visibility plot, uv-plot).

(Images made from naturally weighted visibility data: GIF, Contour plot.)

 

 

Image characteristics: Thermal noise: 0.07 mJy.    Self-calibration noise: 0.36 mJy.

Total CLEAN flux: 465.8 mJy.    Map minimum: -1.9 mJy