------------------- email from Per -------------------------
Date: Thu, 20 Sep 2007 21:08 (HST)
From: Per Friberg 
Subject: [Jcmt_ss] HARP M5 mirror & receptor H12


The M5 mirror was turned around on HARP today. It is believed this will
reduce the array distortions. We will test this in the coming weeks. 
Due to high wind and fog only limited testing could be performed. 
A fast pointing on Jupiter gave a 6"shift and a chopped observation gave 
90K - reasonable close to the ~100K expected considering the weather. 
In light of this make sure to point frequently with HARP.

Per
------------------- end email from Per -------------------------

The subsequent (limited) HARP pointing data (excluding the CONTINUUM measure on Jupiter mentioned above, since it was declared 'bad' in the night-log) are compared with those from the previous night;

   UTdate   No of data  Elevation range    CA +- dS       IE +- dZ
  --------  ----------  ---------------  -----------     -----------
  20070920        24       30-70         15.5 +- 2.1     33.9 +- 2.3
  20070921         7       30-60         14.3 +- 1.2     33.6 +- 2.0
  20070922         8       50-80         15.8 +- 1.4     29.5 +- 2.1
  20070923        11       30-70         16.0 +- 1.8     32.0 +- 2.9
  20070924         9       30-80         16.0 +- 2.5     33.6 +- 2.5
  20070925         8       30-70         15.5 +- 1.7     34.4 +- 3.7

The weather is getting worse . . .

. . so adding together only the 35 data from UT20070921/22/23/24 gives

   UTdate   No of data  Elevation range    CA +- dS       IE +- dZ
  --------  ----------  ---------------  -----------     -----------
  20070921-24    35        30-80         15.6 +- 1.9     35.4 +- 4.2

. . . results that are rather inexplicable in terms of the resulting value of IE, but which in any case are clearly dominated by the nightly collimations. Pre-collimating the nights before adding gives

and

   UTdate   No of data  Elevation range    CA +- dS       IE +- dZ
  --------  ----------  ---------------  -----------     -----------
  20070921-24    35        30-80         15.6 +- 1.9     32.1 +- 2.9

The scatter in elevation is larger than anything we'd call 'nominal', but there are no obvious systematics.