▁had ▁grown ▁to ▁ 1 0 ° ▁in ▁length . ▁ ▁The ▁second ▁independent ▁discovery ▁was ▁made ▁on ▁May ▁ 2 1 ▁by ▁Air ▁France ▁pilot ▁Em ilio ▁Ort iz , ▁from ▁a ▁location ▁about ▁ 4 0 0   km ▁east ▁of ▁Mad agas car . ▁Ort iz ▁saw ▁the ▁com et ▁from ▁his ▁co ck pit , ▁and ▁reported ▁a ▁magnitude ▁of ▁ 0 . 5 ▁to ▁ 1 . 0 ▁and ▁a ▁tail ▁about ▁ 5 – 8 ° ▁long . ▁A ▁few ▁hours ▁later , ▁Carlos ▁B ole l li , ▁a ▁techn ician ▁at ▁the ▁Cer ro ▁Tol olo ▁Inter - American ▁Observ atory ▁in ▁Chile ▁became ▁the ▁third ▁independent ▁discover er ▁of ▁the ▁com et , ▁although ▁he ▁saw ▁only ▁the ▁tail , ▁as ▁the ▁head ▁was ▁beneath ▁the ▁horizon . ▁ ▁Sub sequ ent ▁observations ▁ ▁N umer ous ▁independent ▁discover ies ▁were ▁made ▁in ▁the ▁days ▁immediately ▁following ▁the ▁com et ' s ▁discovery , ▁but ▁astronom ical ▁naming ▁convent ions ▁only ▁allowed ▁the ▁com et ▁to ▁be ▁given ▁the ▁names ▁of ▁the ▁first ▁three . ▁All ▁sight ings ▁of ▁the ▁com et ▁were ▁made ▁from ▁the ▁southern ▁hem is phere , ▁due ▁to ▁the ▁orientation ▁of ▁its ▁orbit ▁with ▁respect ▁to ▁the ▁Earth . ▁ ▁Through out ▁the ▁com et ' s ▁brief ▁appearance , ▁it ▁could ▁only ▁be ▁seen ▁low ▁in ▁the ▁sky ▁for ▁a ▁short ▁time ▁after ▁sun set , ▁but ▁it ▁was ▁most ▁easily ▁visible ▁on ▁May ▁ 2 4 .