index.php
This is a replacement for the CGI Form http://irtfweb.ifa.hawaii.edu/cgi-bin/spex/parangle.cgi
on irtfweb (centos6).

The parangle.cgi was replaced by ./index.php. This form just gathers the user's 
input, call parrefrac, and displays the results.

index.php is equivalent to the cgi version except:
  - call parrefrac using /dev/stdout as the output files (rather that creating 
    actual file that get displayed on the web site).

parrefrac

The parrefrac is a fortran binary called by the web form to calculate the results.

The src/parrefrac.for was copied from /cgi-bin/spex/src/parrefrac.for,
and used here unmodified.  To compile the fortran binary:

   To recompile on irtfweb/centos6:  
	    f77 parrefrac.for -o parrefrac

   To recompile on centos7  using gfortran: 
	    yum install gcc-gfortran                # to install fortran
	    gfortran -ffixed-line-length-none -o parrefrac parrefrac.for

   To recompile on centos8 using gfortran: 
	    dnf install gcc-gfortran                # to install fortran
	    gfortran -ffixed-line-length-none -o parrefrac parrefrac.for

Here is a sample run on the command line:

	./parrefrac 19 49 34.39 4.16807 -1 00 00 19 49 34 615 2 0 /dev/stdout
	  
	 Parallactic Angle =  -87.4428787 or   92.5571213 or   272.557129 degrees 
	  
	 Zenith Angle      =   14.106226 degrees
	 Airmass           =   1.03103268        
	  
	 Differential Atmospheric Refraction in Arcseconds 
		 relative to   2.20000005 microns
	  
	  Lambda      Refraction      Lambda      Refraction 
	  (microns)   (arcsec)       (microns)    (arcsec)
	  0.8000      0.0935          3.0000     -0.0065
	  1.0000      0.0545          3.2000     -0.0074
	  1.2000      0.0334          3.4000     -0.0082
	  1.4000      0.0208          3.6000     -0.0088
	  1.6000      0.0126          3.8000     -0.0094
	  1.8000      0.0070          4.0000     -0.0098
	  2.0000      0.0030          4.2000     -0.0102
	  2.2000      0.0000          4.4000     -0.0106
	  2.4000     -0.0022          4.6000     -0.0108
	  2.6000     -0.0040          4.8000     -0.0111
	  2.8000     -0.0054          5.0000     -0.0113