▁absolute ▁magnitude ▁in ▁a ▁particular ▁pass band , ▁especially ▁for ▁very ▁hot ▁or ▁very ▁cool ▁objects . ▁ ▁Bol ometric ▁magn itudes ▁are ▁formally ▁defined ▁based ▁on ▁stell ar ▁lum inos ity ▁in ▁w att s , ▁and ▁are ▁normal ised ▁to ▁be ▁approximately ▁equal ▁to ▁M V ▁for ▁ ▁yellow ▁stars . ▁ ▁Ab solute ▁magn itudes ▁for ▁solar ▁system ▁objects ▁are ▁frequently ▁quoted ▁based ▁on ▁a ▁distance ▁of ▁ 1 ▁A U . ▁ ▁These ▁are ▁referred ▁to ▁with ▁a ▁capital ▁H ▁symbol . ▁ ▁Since ▁these ▁objects ▁are ▁lit ▁primarily ▁by ▁reflected ▁light ▁from ▁the ▁sun , ▁an ▁H ▁magnitude ▁is ▁defined ▁as ▁the ▁apparent ▁magnitude ▁of ▁the ▁object ▁at ▁ 1 ▁A U ▁from ▁the ▁sun ▁and ▁ 1 ▁A U ▁from ▁the ▁observer . ▁ ▁Ex amples ▁▁ ▁The ▁following ▁is ▁a ▁table ▁giving ▁apparent ▁magn itudes ▁for ▁cel est ial ▁objects ▁and ▁artificial ▁sat ell ites ▁r anging ▁from ▁the ▁Sun ▁to ▁the ▁f ain test ▁object ▁visible ▁with ▁the ▁Hub ble ▁Space ▁T eles cope ▁( H ST ): ▁ ▁Other ▁scales ▁▁ ▁Under ▁P og son ' s ▁system ▁the ▁star ▁V ega ▁was ▁used ▁as ▁the ▁fundamental ▁reference ▁star , ▁with ▁an ▁apparent ▁magnitude ▁defined ▁to ▁be ▁zero , ▁regardless ▁of ▁measurement ▁technique ▁or ▁w avel ength ▁filter . ▁This ▁is ▁why ▁objects ▁br ighter ▁than ▁V ega , ▁such ▁as ▁Si ri us ▁( V ega ▁magnitude ▁of ▁− 1 . 4 6 . ▁or ▁− 1 . 5 ), ▁have ▁negative ▁magn