▁Field ▁South ▁is ▁the ▁single ▁target ▁where ▁Ch andra ▁has ▁observed ▁the ▁longest . ▁ ▁Mult is pect ral ▁observations ▁of ▁the ▁region ▁were ▁carried ▁out ▁in ▁collaboration ▁with ▁the ▁Very ▁Lar ge ▁T eles cope ▁and ▁the ▁Par anal ▁Observ atory . ▁Through ▁the ▁course ▁of ▁these ▁investig ations , ▁the ▁X - ray ▁background ▁was ▁determined ▁to ▁have ▁origin ated ▁from ▁the ▁central ▁super mass ive ▁black ▁holes ▁of ▁distant ▁galaxies , ▁and ▁a ▁better ▁character ization ▁of ▁Type - II ▁Qu as ars ▁was ▁obtained . ▁ ▁The ▁C DF S ▁discovered ▁over ▁ 3 0 0 ▁X - ray ▁sources , ▁many ▁of ▁them ▁from ▁" low ▁lum inos ity " ▁AG N ▁lying ▁about ▁ 9 ▁billion ▁light ▁years ▁away . ▁The ▁study ▁also ▁discovered ▁the ▁then ▁most ▁distant ▁Qu as ar ▁ 2 , ▁lying ▁at ▁red shift ▁z = 3 . 7 , ▁some ▁ 1 2 ▁billion ▁light ▁years ▁away . ▁ ▁In ▁ 2 0 1 4 ▁and ▁ 2 0 1 5 ▁astronom ers ▁detected ▁four ▁very ▁inten se ▁burst ▁of ▁X - ray s , ▁currently ▁un exp la ined , ▁from ▁a ▁small ▁galax y , ▁known ▁as ▁C DF - S ▁X T 1 , ▁about ▁ 1 1 ▁billion ▁light ▁years ▁from ▁Earth ▁in ▁the ▁For na x ▁const ell ation . ▁ ▁See ▁also ▁ ▁Hub ble ▁Deep ▁Field ▁South ▁ ▁List ▁of ▁Deep ▁Field s ▁ ▁Notes ▁ ▁References ▁ ▁NASA ▁PR ▁ 0 1 - 3