Results of the first geodetic VLBI experiment with IRBENE32 station

On 2016.11.14 station IRBENE32 located at the Baltic coast near town of Ventspils joined VLBI experiment r1766 for 16 hours. Since at the moment the station does not have S/X receiver, it recorded only X-band. The experiment was successful. Here is the main result:

Position of IRBENE32 on 2000.0 epoch

                        X            Y            Z

  IRBENE32  pos   3183649.615  1276902.735  5359264.576  m
  IRBENE32  vel       -16.85        15.30         6.36   mm/yr  NNR-NUVEL1A

Velocity of IRBENE32 is computed from the NNR-NUVEL1A model of tectonic motion.

Position of IRBENE32 on 2016.11.15

                        X                       Y                   Z

  IRBENE32  pos   3183649.331 +- 0.002  1276902.993 -+ 0.002  5359264.684 -+ 0.004  m

X-band only group delays from r1766 experiment were used in a global VLBI least square solution together with over 6000 VLBI experiments since 1980 through 2016. The ionosphere contribution to group delay was modeled using the total electron contents maps from CODE GNSS data analysis. Wrms of postifit residuals is 27.92 ps. Estimate of the axis offset length is zero within formal uncertainties. Position differnces with respect to the a priori value: -11.67, 0.99, -26.32 m.

Fringe plots

Apparently, receiver's good range ends at 8.4 GHz.

Other plots

X-band group delay postfit residuals

Phase calibration signal

Amplitude of phase calibration is too low. As a result phase calibration phases are too low. Phase cal was not used during data analysis.

System temperature

Thus, normal Tsys range is 50–55 K at elevations above 20°.

Sensitivity

Estimates of SEFD from geodetic VLBI experiments is problematic since antenna gain curves of only few antennas are known. I estimated the ratio of fringe amplitudes at long baseline Ir/Ts and Ir/Wz:

The average ratio of amplitudes is 0.42, i.e. sensitivity of IREBEN32 was a factor of 2.4 worse than WETTZELL. Considering the nominal SEFD of WETTZELL 750K, we get IRBENE32 SEFD 1800Jy averaged over the bandwidth. However, the sensitivity at 8.2 GHz is approximately 1.5 times better than on average, and sensitivity at 8.9 GHz is approximately 1.5 times worse than on average. Therefore, tentative IRBENE32 SEFD estimates are:

8.2 GHz 1200 Jy
8.9 GHz 2700 Jy

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Last update: 2016.11.30_23:50:45
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