This work:   /home/sco/ACM_work_Oct2019/red_20191022/Test1

Date rejection work for zpandsky 
================================
The phot routine, near the end of its work, produces a table 
file with basename:  ${basename}_ZP
Note: This table is built with:   zpmido_table_markII ${basename}.fits ZP

For our example with 20191022T025524.2_acm_sci.fits these fiels are:
 20191022T025524.2_acm_sci_ZP.params,parlab,table 

We can inspect our ZP,SKY data space in a way where we can view images with: 
  table_ds9_panner 20191022T025524.2_acm_sci_ZP 20191022T025524.2_acm_sci.fits Xcen Ycen ZPSEC MeanSky 

In this example I view the parameter and find a clump of "valid" points
thate would indicate good values of: 
   ZPSEC   = -2.76438       
   MeanSky = 62.2678 adu 

I can use the b (box) option to mark these points in a box. 
The marked points are in:    xyf.in
Here is an example of the top of this file: 
Keys for icurs5.py
ZP for 1-sec  [= mstan-{m30+2.5log(Texp)} ]
Average value in sky annulus (adu)
    -99.0000    1263.1650    0           1
     -2.6924     115.6200    0           2
    -99.0000      81.0960    0           3
     -2.7434      78.7610    1           4
     -2.7294      79.7960    1           5
     -2.7494      66.4100    1           6

What we want to do is average the points maeked in column 3 with "1". 
s I use the code: point_selector_stats.sh

Usage: point_selector_stats.sh xyf.in X 0 N 
arg1 - name of xyf.in-type file (usually xyf.in) 
arg2 - Axis to to analyzed (X or Y) )  
arg3 - flag value to be pulled (usually 0 or 1)  
arg4 - run in debug/verbose mode (Y/N)  

Hence to get my stats for the manually isolated points:
% point_selector_stats.sh xyf.in X 1 N
    -2.76508     -2.76490      0.06190      0.01170       28   (mean,mediam,sig,me,n) 
% point_selector_stats.sh xyf.in Y 1 N
    63.62451     62.91000      5.34211      1.00956       28   (mean,mediam,sig,me,n) 

If I were taking the median as the value, and me as the error I would 
say my best values are:     
      ZPSEC = -2.76490 -+ 0.01170
      SKY   = 62.91000 -+ 1.00956
 
How does this compare to what my current version of zpandsky.sh gives? 
Usage: zpandsky.sh 20191022T025524.2_acm_sci_ZP N 
arg1 - baseame of FITS image measured          
arg2 - run in verbose/debug mode (Y/N) 

% zpandsky.sh 20191022T025524.2_acm_sci_ZP N 
   -2.7669   0.0648    32        63.6460       2.2699    32   (zp,zperr,nz,sky,skyerr,ns) 
Here we would get: 
      ZPSEC = -2.7669  -+ 0.0648 
      SKY   = 63.6460  -+ 2.2699