[alma-config] topography mask

[Seiichi Sakamoto]

Colleagues,

I personally prefer to make steps forward to develop the cost mask.  
We can start from 2-levels and sophisticate our model 
as we learn more about the geological conditions and the cost.  
This approach will always provide us with the best estimate of 
the construction cost of the proposed configurations, 
and will also help us to clarify what should be known next 
to sophisticate the model further.  

On a different point: I do not really understand why each 
configuration should be leveled to the local geoid.  
Provided that each configuration is independent with the others 
(that may apply at least to the maximum 10-km baseline), 
linear tilt throughout the area of each configuration 
may not bring extra complexity to the array.  
So I suggest to use the second-order derivatives of the altitude 
instead of the local surface gradients (the first-order ones).  

Let me know your opinion.  

Seiichi

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Seiichi Sakamoto
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LMSA/ALMA Project Office
Nobeyama Radio Observatory
Minamimaki, Minamisaku
Nagano 384-1305, Japan
phone:  +81-267-98-4378
fax:    +81-267-98-4508
e-mail: seiichi at nro.nao.ac.jp
URL:    http://www.nro.nao.ac.jp/~seiichi
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