[mmaimcal] pointing error

[morita]

Hi all,

attached file is a further result of the imaging simulations
including the pointing error. Rms pointing error is assumed about 
1/20 FWHM of the primary beam.  The ring array was used for
these simulations.  The figure shows the image qualities 
normalized by those without the pointing error as a function of 
source size.  A 10-compact-Gaussian model was used except for
the case of source size of 0, for which a single Gaussian was used.

Image quality decrease to about 70 - 80 % for source size = 0.
For this case, we can explain as follows.

Rms pointing error of about 1/20 FWHM causes visiblity amplitude
error about 0.3 % for a point source at the center of the FOV.
This error is correspoinding to rms on-source error of about 3.0e-5
because the far sidelobe level is about 1% of the peak.
Since rms off-source error without pointing error is about 2.7e-5 
(DR=37,000), total off-source error is about 4.0e-5 and corresponding
DR is about 70 % of that for no pointing error case.

Regards,
Koh-Ichiro
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