[alma-config]borehole locations

[Simon Radford]

John,

The rest of us all thought it was very productive for you to visit Chajnantor last week; I hope you agree!

As we discussed, the APEX group will have several boreholes drilled in January to examine the underlying rock structure at their candidate antenna locations. For ALMA, Daniel Hofstadt and I agreed to make 16 more boreholes at the same time: 

  - a 3 x 3, 500 m grid centered on the existing borehole for Chajnantor South (8 holes),
  - 1 hole on each of 2 fingers running SW from the array center (2 holes),
  - 6 holes on the ridge NE of Cordon Honar, 3 above the existing road, and three below.

Do you agree with this distribution of holes? Especially the number on the ridge compared with other areas? Are there other points we should sample (keeping the total constant)?

Please specify to Guillermo (and to the configuration group) the coordinates for the boreholes before Friday, December 21. 

Simon

The existing borehole is about 16 m from the true center of Chajnantor South, 7453228.830  627807.166  5016.792.  

Boreholes; Memo 326       UTM 19 K (SAm56)  
1 (Pampa la Bola)       7460565      633839 
2 (ASTE)                7459405      633129 
3 (Chajnantor N)        7454415      627599 
4 (Chajnantor S)        7453215      627799 
5 (Saddle point)        7456215      631439 
6 (Chascon E)           7457645      637899 

Note Memo 326 gives the borehole locations in UTM coordinates on the WGS84 datum. The coordinates listed here have been corrected to the Prov. S. Am. 1956 datum. (Note, furthermore, the coordinates in that memo for the NRAO and NRO containers, although
listed as WGS84, actually appear to be on the SAm56 datum.) 

http://www.tuc.nrao.edu/alma/site/Chajnantor/maps/coordinates.html