Stellar absolute magnitudes are usually designated with a capital M with a subscript to indicate the passband. For example, M V is the magnitude at 10 parsecs in the V passband. A bolometric magnitude (M bol) is an absolute magnitude adjusted to take account of radiation across all wavelengths; it is typically smaller (i.e. brighter) than an absolute magnitude in a particular passband, especially for very hot or very cool objects. Bolometric magnitudes are formally defined based on stellar luminosity in watts, and are normalised to be approximately equal to M V for yellow stars.