/***********************************************************************//**
* @brief Return instrument response
*
* @param[in] event Event.
* @param[in] source Source.
* @param[in] obs Observation.
* @return Instrument response.
*
* Returns the instrument response for a given event, source and observation.
***************************************************************************/
double GCOMResponse::irf(const GEvent& event,
const GSource& source,
const GObservation& obs) const
{
// Initialise IRF value
double irf = 0.0;
// Select IRF depending on the spatial model type
switch (source.model()->code()) {
case GMODEL_SPATIAL_POINT_SOURCE:
{
const GModelSpatialPointSource* src =
static_cast<const GModelSpatialPointSource*>(source.model());
GPhoton photon(src->dir(), source.energy(), source.time());
irf = this->irf(event, photon, obs);
}
break;
case GMODEL_SPATIAL_RADIAL:
case GMODEL_SPATIAL_ELLIPTICAL:
case GMODEL_SPATIAL_DIFFUSE:
{
std::string msg = "Response computation not yet implemented for "
"spatial model type \""+source.model()->type()+"\".";
throw GException::feature_not_implemented(G_IRF, msg);
}
break;
default:
break;
}
// Return IRF value
return irf;
}
/***********************************************************************//**
* @brief Return instrument response to point source
*
* @param[in] event Observed event.
* @param[in] source Source.
* @param[in] obs Observation (not used).
* @return Instrument response to point source.
*
* Returns the instrument response to a specified point source.
***************************************************************************/
double GCTAResponseCube::irf_ptsrc(const GEvent& event,
const GSource& source,
const GObservation& obs) const
{
// Initialise IRF
double irf = 0.0;
// Get pointer to model source model
const GModelSpatialPointSource* ptsrc = static_cast<const GModelSpatialPointSource*>(source.model());
// Get point source direction
GSkyDir srcDir = ptsrc->dir();
// Get pointer on CTA event bin
if (!event.is_bin()) {
std::string msg = "The current event is not a CTA event bin. "
"This method only works on binned CTA data. Please "
"make sure that a CTA observation containing binned "
"CTA data is provided.";
throw GException::invalid_value(G_IRF_PTSRC, msg);
}
const GCTAEventBin* bin = static_cast<const GCTAEventBin*>(&event);
// Determine angular separation between true and measured photon
// direction in radians
double delta = bin->dir().dir().dist(srcDir);
// Get maximum angular separation for PSF (in radians)
double delta_max = psf().delta_max();
// Get livetime (in seconds)
double livetime = exposure().livetime();
// Continue only if livetime is >0 and if we're sufficiently close
// to the PSF
if ((livetime > 0.0) && (delta <= delta_max)) {
// Get exposure
irf = exposure()(srcDir, source.energy());
// Multiply-in PSF
if (irf > 0.0) {
// Recover effective area from exposure
irf /= livetime;
// Get PSF component
irf *= psf()(srcDir, delta, source.energy());
// Apply deadtime correction
irf *= exposure().deadc();
} // endif: exposure was non-zero
} // endif: we were sufficiently close to PSF and livetime >0
// Compile option: Check for NaN/Inf
#if defined(G_NAN_CHECK)
if (gammalib::is_notanumber(irf) || gammalib::is_infinite(irf)) {
std::cout << "*** ERROR: GCTAResponseCube::irf_ptsrc:";
std::cout << " NaN/Inf encountered";
std::cout << " irf=" << irf;
std::cout << std::endl;
}
#endif
// Return IRF value
return irf;
}