OF THE ROGER N. CLARK

VISUAL ASTRONOMY OF THE DEEP SKY
Table F.5 (cont. )
APPENDIX F: OPTIMUM DETECTION MAGNIFICATIONS FOR DEEP-SKY OBJECTS
Table F.5 (cont. )
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10
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15
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100
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1
i =7
ang = alog10(angle )
if (ang. le .angx(l)) go to 100
if (ang.ge.angx(7)) go to 200
find angx values bounding ang
do 10 i = 1,6
if ((angx(i).lt .ang) .and . (angx (i+1).ge.ang )) go to 15
cont inue
interpolate along the angle direction.
xl is the cont ra st interpolted in the angle direction
at the first bounding sb value
x2 is the contra st interpolted in the angle direction
at the second bounding sb value
xl (ang-angx(i)) 1 (angx(i+1 ) - angx(i)) *
(sbx( i+1 ,isb1 )-sbx(i,isb1)) + sbx(i,isb1)
x2 (ang-angx(i)) 1 (angx(i+1 ) -angx(i)) *
1 (sbx( i+1 ,isb2)-sbx(i,isb2)) + sbx(i,isb2)
go to 500
ang less than beginning of table , so extraploate
xl = sbxC l ,isb)
x2 = sbx( 1,i sb2)
go to 500
ang greater than last in table , so extraploate
200 xl (ang-angx(6)) 1 (angx(7)-angx(6)) *
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500
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x2
(sbx(7,isb1) - sbx(6,isb1 )) + sbx(6,isbl)
(ang-angx(6)) 1 (angx(7) - angx(6)) *
(sbx(7 ,isb2)-sbx(6,isb2)) + sbx(6,isb2 )
Now interpolate (or extrapolate) along sb direction
compute thrcon from xl , x2
if (sb .It. 4.0) then
x = xl
else if (sb .ge. 27 .0) then
x (sb-27 .0)*(x2-xl ) + x2
else
x (sb-real(int(sb) )) * (x2-x1) + xl
end if
if (x.gt. 37 .0) x=37 .0
if (x.lt.-37 .0) x= -37 .0
thrcon
10 .0 * * x
c*de bug :
c*debug wr ite (6,504) i, isb1
c*debug04 format (' i=' ,i6, ' isb1=' ,i6)
c*debug lla = i+1
c*debug if (iia .gt. 7) iia = 7
c*debug
write (6,505) i,ang , angx(i), angx(iia) , sbx(i,isb1),
c*debug 1 sbx(iia ,isb1), x
c*debug505 format (lx,
c*debug 1 ang angx(i) angx (i+1 ) sbx(i,isb1 )
sbx( i+1 ,isb1)' ,
c*debug 2 x',/, lx, i2, 6(f7.3, Ix) , I, lx, 72(lh- ))
return
end
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real*4 function opvang (sb)
implicit integer*4 (i - n)
this function computes the optimum visual angle
of an object given the background surface brightness (sb)
sbx surface brightness data for 18 values of optimum
visual angle .
opv log base 10 optimum visual angles for sbx values
sbx and opv are used to interpolate to the opvang given
by sb.
real*4 sbx( 18) , opv( 18)
data sbx 14 .0,9.0,11.0,13 .0,14.0,15.0,16.0,17.0,18.0,
1 19.0,20.0,21.0,22.0,23.0,24.0,25.0,26.0,27.01
data opv 10.97,1.01,1.04,1.07,1.11,1.14,1.20,1.26,1.36,
1 1.49 , 1.62,1.71,1.79,1.83,1.86,1.90, 1.96,2.071
if (sb.le. sbx( l)) go to 100
if (sb.ge.sbx( 18) ) go to 200
find sbx values bounding sb
do 10 i = 1,17
if ((sbx (i).lt.sb) .and .(sbx ( i+1 ).ge .sb)) go to 15
10 cont inue
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interpolate
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