41 
Next we form the weight number of the expression (137). As usual 
we have 
  
n — Puer gm 
Qnpny == a SA —iPQu+ Xie 
n i=1 WW i=p+1 
(n — p iz» p^ 2(n—ppier 
LEM xot E xe r0 F000, 
"d i=p+1 n i=1 : 
2 p? imm : 
LE ET az idu (138) 
n°; p+1 
But 
i=p ; 2p—1)(p—1)p 
o ipe Bác ta AH SRE NE se) 
i=1 
2 n—-i+12=124 224324 ..... + (n — p — 1? + (n — p? = 
i=p+1 
(2% — 2 p + 1) (n — p + 1) (n — p) 
E ———— e tm (140) 
6 
i=p p (1 — p) i=» : (n — p) (n — p 4- 1) 
x (1 — 2) m= 2 > ín rd c 1) — 9 ; (141) 
i (= DE 
After substitution of (139)—(141) into (138) and some elementary 
calculations and rearrangements we obtain 
p (n — p) |2p(n — p) +1 
| Pere ^ SER Qu + 0,2 + Qu. (142) 
Qn, Ry 6 
n 
Substituting the expressions (103)—(106) we find 
p (n — p) 
7 A 25 € 
ax (14 p (n — p) + 25} (143) 
nA. 
The standard error of a corrected X-coordinate will consequently be 
determined as 
my = 8 | QrçRy (144) 
where s, is the standard error of the image coordinate measurements. 
  
rd 
Ue eu pp 
  
  
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