bool SkyPoint::checkBendLight() {
// First see if we are close enough to the sun to bother about the
// gravitational lensing effect. We correct for the effect at
// least till b = 10 solar radii, where the effect is only about
// 0.06". Assuming min. sun-earth distance is 200 solar radii.
static const dms maxAngle( 1.75 * ( 30.0 / 200.0) / dms::DegToRad );
if( !m_Sun )
m_Sun = (KSSun*) KStarsData::Instance()->skyComposite()->findByName( "Sun" );
// TODO: This can be optimized further. We only need a ballpark estimate of the distance to the sun to start with.
return ( fabs( angularDistanceTo( static_cast<const SkyPoint *>(m_Sun) ).Degrees() ) <= maxAngle.Degrees() ); // NOTE: dynamic_cast is slow and not important here.
}
bool SkyPoint::bendlight() {
// NOTE: This should be applied before aberration
// NOTE: One must call checkBendLight() before unnecessarily calling this.
// We correct for GR effects
Q_ASSERT( m_Sun );
double corr_sec = 1.75 * m_Sun->physicalSize() / ( m_Sun->rearth() * AU_KM * angularDistanceTo( static_cast<const SkyPoint *>(m_Sun) ).sin() );
Q_ASSERT( corr_sec > 0 );
SkyPoint sp = moveAway( *m_Sun, corr_sec );
setRA( sp.ra() );
setDec( sp.dec() );
return true;
}
bool SkyPoint::bendlight() {
// NOTE: This should be applied before aberration
// NOTE: One must call checkBendLight() before unnecessarily calling this.
// We correct for GR effects
// NOTE: This code is buggy. The sun needs to be initialized to
// the current epoch -- but we are not certain that this is the
// case. We have, as of now, no way of telling if the sun is
// initialized or not. If we initialize the sun here, we will be
// slowing down the program rather substantially and potentially
// introducing bugs. Therefore, we just ignore this problem, and
// hope that whenever the user is interested in seeing the effects
// of GR, we have the sun initialized correctly. This is usually
// the case. When the sun is not correctly initialized, rearth()
// is not computed, so we just assume it is nominally equal to 1
// AU to get a reasonable estimate.
Q_ASSERT( m_Sun );
double corr_sec = 1.75 * m_Sun->physicalSize() / ( ( std::isfinite( m_Sun->rearth() ) ? m_Sun->rearth() : 1 ) * AU_KM * angularDistanceTo( static_cast<const SkyPoint *>(m_Sun) ).sin() );
Q_ASSERT( corr_sec > 0 );
SkyPoint sp = moveAway( *m_Sun, corr_sec );
setRA( sp.ra() );
setDec( sp.dec() );
return true;
}
