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<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'>ALMA Memo # 488</span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'>Wide-Field Imaging of </span></font><font
size=3 face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>ALMA</span></font><font
size=3 face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
with the Atacama Compact Array: Imaging Simulations</span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'>Takahiro Tsutsumi</span></font><font
size=3 face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>(NAOJ),
Koh-Ichiro Morita(NAOJ), Tetsuo Hasegawa(NAOJ), Jerome Pety(IRAM/Obs. de Paris)</span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'>2004-03-21</span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'>Keywords: mosaicing,
wide-field imaging, simulations, ACA</span></font></p>
<p class=MsoPlainText><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>We examined the
significance of the Atacama Compact Array (ACA) in wide-field imaging of </span></font>ALMA
through imaging simulations. The purpose of the simulations are to:</p>
<p class=MsoNormal style='text-autospace:none'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'> i) demonstrate
importance of ACA in wide-field imaging with </span></font>ALMA and</p>
<p class=MsoNormal style='text-autospace:none'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'> ii) identify which
component of errors has more significant influence than others on quality of final
images obtained with ALMA+ACA using realistic parameters as to give
feedback on designing and specifications of the ACA system. We particularly
focused on the following aspects: difference on the ACA configuration design
and effects of pointing errors, amplitude errors, and atmospheric phase errors.
The simulations indicate that how densely packed the ACA configuration is an
important factor for good imaging performance. The pointing errors at submm
waves seriously degrade fidelity of an image. The atmospheric phase fluctuation
also plays a major role. As indicated by previous works, our study indicates
that ACA can boost the quality of wide-field imaging with </span></font>ALMA by
a factor of two or more for many cases, while dependency on structures of model
images exists. In presence of all the errors, the projected goal of the imaging
fidelity of 20 or better for ALMA when ACA is included, can be achieved if the
current specifications are met.</p>
<p class=MsoNormal style='text-autospace:none'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'> </span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>View a pdf version of
ALMA Memo #488. </span></font></p>
<p class=MsoNormal style='text-autospace:none'><u><font size=2 color=blue
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:blue'><a
href="http://www.alma.nrao.edu/memos/html-memos/alma488/memo488.pdf">http://www.alma.nrao.edu/memos/html-memos/alma488/memo488.pdf</a></span></font></u></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
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