QString SkyObjItem::getSurfaceBrightness() const
{
/** Surface Brightness is applicable only for extended light sources like
* Deep-Sky Objects. Here we use the formula SB = m + log10(a*b/4)
* where m is the magnitude of the sky-object. a and b are the major and minor
* axis lengths of the objects respectively in arcminutes. SB is the surface
* brightness obtained in mag * arcminutes^-2
*/
DeepSkyObject *dso = (DeepSkyObject *)m_So;
float SB = m_So->mag() + 2.5 * log10(dso->a() * dso->b() / 4);
switch(getType())
{
case Galaxy:
case Nebula:
return KGlobal::locale()->formatNumber(SB, 2) + " mag/arcmin^2";
default:
return QString(" --"); // Not applicable for other sky-objects
}
}
