ACTCollaboration / libactpol

ACTpol utility library

libactpol

Usage

Setup array pointing

#include <actpol/actpol.h>

ACTpolArray *array = ACTpolArray_alloc(nhorns);
ACTpolArray_init(array, freq_GHz, array_center_x, array_center_y);

for (int i = 0; i < nhorns; i++) {
    ...
    ACTpolFeedhorn_init(array->horn+i, x, y, a);
}

Compute array coordinates

ACTpolArrayCoords *coords = ACTpolArrayCoords_alloc(array);
ACTpolArrayCoords_init(coords, ACTPOL_COORDSYS_RA_SINDEC);

ACTpolState *state = ACTpolState_alloc();
ACTpolState_init(state);

ACTpolWeather weather;
ACTpolWeather_default(&weather);

for (int i = 0; i < nscans; i++)
{
  ACTpolScan scan;
  ACTpolScan_init(&scan, scan_alt, scan_az, scan_throw);

  // only needs to be called when scan or weather changes
  ACTpolArrayCoords_update_refraction(coords, &scan, &weather);
  ...
  for (j = 0; j < nsamples; j++)
  {
    ...
    ACTpolState_update(state, unixtime, boresight_alt, boresight_az);
    ACTpolArrayCoords_update(coords, state);

    for (k = 0; k < nhorns; k++)
    {
      ACTpolFeedhornCoords *fc = coords->horn + k;
      printf("%g %g\n", fc->a, fc->b); // a = ra, b = sin(dec)
      printf("%g %g\n", fc->sin2gamma1, fc->cos2gamma1);
      printf("%g %g\n", fc->sin2gamma2, fc->cos2gamma2);
    }
  }
}

Read dirfile

#include <actpol/dirfile.h>

ACTpolDirfile *dirfile = ACTpolDirfile_open("/path/to/dirfile");

if (ACTpolDirfile_has_channel(dirfile, "Enc_Az_Deg")) {
  int nsamples;
  double *az = ACTpolDirfile_read_double_channel(dirfile, "Enc_Az_Deg", &nsamples);
  ...
}

ACTpolDirfile_close(dirfile);

Create and write map

ACTpolMap *map = ACTpolMap_new(ra_min, ra_max, dec_min, dec_max, pixsize);

for (...)
{
  ...
  //long pix = ACTpolMap_sky2pix(map, ra, dec);
  long pix = ACTpolMap_sky2pix_cea_fast(map, ra, sindec);
  map->data[pix] += ...
}

ACTpolMap_write_to_fits(map, "filename");
ACTpolMap_free(map);