Angular selection function

We provide the angular selection function files in a format of BINARY that are zipped into a file, skymask.data.tar.gz:
[angular selection function]
    -2: if a target locates inside of bright star mask,
    -1: if outside of the survey window geometry,
   >0: if inside of the survey window geometry.

Note that we made two arrays of square pixels of size 0.025° × 0.025° in the (λ,η) sky coordinates which cover the analysis regions, and stored the angular selection function.

sky[num]maskb.data025  where the [num] represents survey area:
[num]   1: main survey area , 2: three southern stripes (76, 82, and 86) with λ>120°, 3: the southern stripes with λ<0°,  4: Hubble Deep Field area

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The FORTARN statements to read the angular selection function, wt are as follows;

      parameter (pixsize=0.025) ! pixsize=pixel on the sky in a survey coordinate (lambda,eta)
      parameter (ne1=3200,ne2=1200,ne3=1200,ne4=208)
      parameter (nl1=5200,nl2=2400,nl3=2400,nl4=552)

      open(7,file='sky1maskb.data025', form='unformatted')   
      read(7)((amask1(ilambda,ieta),ilambda=1,nl1),ieta=1,ne1)
      close(7)
      open(7,file='sky1maskb.data025', form='unformatted')
      read(7)((amask2(ilambda,ieta),ilambda=1,nl2),ieta=1,ne2)
      close(7)
      open(7,file='sky3maskb.data025', form='unformatted')
      read(7)((amask3(ilambda,ieta),ilambda=1,nl3),ieta=1,ne3)
      close(7)
      open(7,file='sky4maskb.data025', form='unformatted')
      read(7)((amask4(ilambda,ieta),ilambda=1,nl4),ieta=1,ne4)
      close(7)

     if(lambda.ge.-65.and.lambda.le. 65.and. eta.le. 43.and.eta.ge.-37)then
        ieta = int((43-eta)/pixsize)+1
        ilambda = int((lambda+65)/pixsize)+1
        wt = amask1(ilambda,ieta)
     else if(lambda.ge.120.and.lambda.le.180.and.eta.le.-20.and. eta.ge.-50)then
        ieta = int((-20-eta)/pixsize)+1
        ilambda = int((lambda-120.)/pixsize)+1
        wt = amask2(ilambda,ieta)
      else if(lambda.ge.-180.and.lambda.le.-120.and.eta.le.-20.and.eta.ge.-50)then
        ieta = int((-20-eta)/pixsize)+1
        ilambda = int((lambda+180.)/pixsize)+1
        wt = amask3(ilambda,ieta)
      else if(lambda.ge.22.and.lambda.le.37.and.eta.le.51.5.and. eta.ge.46.)then
        ieta = int((51.3-eta)/pixsize)+1
        ilambda = int((lambda-22.5)/pixsize)+1
        wt = amask4(ilambda,ieta)
      endif