antenna_main.cpp

// Copyright Bruce Allen 2017
// Compile with gcc -o antenna antenna.c -lm

// REMAINING THINGS TO CHECK:

// (a) sign conventions for h, which arm is positive CONFIRMED.  VIRGO
//  AND LIGO DEFINE THE POSITIVE ARM AS "X" where X defined by right
//  hand rule with two arms and Z away from center of earth.

// (b) direction and origin conventions for the polarization axis The
// convention for LAL is that psi is the angle that the source plane
// is rotated CCW as viewed from the Earth.  The convention in my
// calculation is the opposite.  So in my code I have changed the sign
// inside get_antenna() so that the arguments now correspond to LAL
// ones.  Thus in this code, the conventions correspond to LAL.

// IOTA is zero when orbital angular momentum points to earth
// PSI is orbital plane rotation CCW as viewed from Earth

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include "antenna_lib.h"

// This function requires two floating point arguments on the command
// line, iota and psi, angles in degrees.
int main(int argc, char *argv[]) {
   // to loop over detectors
   int i;


   // Test RA/DEC conversion with GW170817
   // Event time
   // GPS 1187008882
   // UTC:	Thu 2017 Aug 17	12:41:04
   // Julian Day 2457983.02852
   // Modified Julian Day 57982.52852
   // Unix Epoch 1502973664
   // Right ascension: 13h 09m 47.2s
   // Declination: −23° 23′ 4″
   // We will need to convert this to location over the Earth at the
   // event time.  It will turn out to be:
   // Lattitude −23.3844 degrees (south of equator)
   // Longitude 41.092981 degrees (east of Greenwich)
   
   double lat,lon;
   epoch_RA_DEC_to_Latt_Long(1502973664, 13+9.0/60.0+47.2/3600.0, -(23+23.0/60.0+4.0/3600.0), &lat,&lon);
   printf("GW170817 Lattitude = %f Longitude = %f\n", lat, lon);
   exit(0);
   
   // to pass data in and out
   struct InputStruct myinput;
   struct OutputStruct myoutput;

   // check syntax crudely, issue usage message
   if (argc != 3) {
      fprintf(stderr,
	      "Wrong argument count! Correct usage:\n"
	      "%s float_iota_in_degrees float_psi_in_degrees\n",
	      argv[0]);
      exit(1);
   }
   myinput.iota = atof(argv[1]);
   myinput.psi = atof(argv[2]);

   // pass inclination angle, polarization axis, orientation offsets
   for (i=0;i<3;i++) myinput.orientation[i]=0.0;
   
   printf("Iota = %f degrees\nPsi = %f degrees\n", myinput.iota, myinput.psi);

   // now compute responses
   get_antenna(&myoutput, &myinput);

   for (i=0; i<5; i++) print_detector(i);
   print_source();
   print_patterns();

   // degree character in UTF-8 character set (most likely terminal type!)
   int deg1=0xC2, deg2=0xB0;
   
   // Now display waveforms
   for (i=0; i<5; i++)
      printf("For detector %s the waveform is %.3f w^2 sin(2w[t%+.1f ms]%+.1f%c%c)\n",
	     myoutput.name[i], myoutput.amp[i], myoutput.dt[i], myoutput.phase[i], deg1, deg2);

   // prints angles between line in between detector i arms and direction to source
   // for (i=0; i<5; i++) print_angles(i);

   return 0;
}