5 ▁whole - frame ▁photograph s ▁of ▁the ▁K ui per ▁quad rangle ; ▁Mercur y ▁II , ▁ 1 3 ▁whole - frame ▁photograph s ; ▁and ▁Mercur y ▁III , ▁ 7 0 ▁quarter - frame ▁photograph s . ▁The ▁photograph s ▁include ▁ 1 9 ▁s tere op airs ▁in ▁the ▁southern ▁part ▁of ▁the ▁quad rangle . ▁The ▁most ▁distant ▁of ▁the ▁photograph s ▁was ▁taken ▁at ▁an ▁alt itude ▁of ▁ 8 9 , 8 7 9   km , ▁the ▁closest ▁at ▁an ▁alt itude ▁of ▁ 7 , 5 4 6   km . ▁Resol ution , ▁therefore , ▁var ies ▁widely ▁but ▁ranges ▁from ▁about ▁ 1 . 5 ▁to ▁ 2 . 0   km ▁over ▁most ▁of ▁the ▁area . ▁A ▁wide ▁range ▁( more ▁than ▁ 5 0 ▁deg ) ▁of ▁both ▁view ing ▁and ▁solar ▁ill um ination ▁angles ▁pre cludes ▁a ▁high ▁degree ▁of ▁mapping ▁consist ency . ▁The ▁eastern most ▁ 1 0 ° ▁of ▁the ▁quad rangle ▁is ▁beyond ▁the ▁evening ▁termin ator . ▁A ▁low ▁angle ▁of ▁solar ▁ill um ination ▁and ▁a ▁high ▁view ing ▁angle ▁make ▁possible ▁disc rim ination ▁of ▁top ographic ▁detail ▁near ▁the ▁termin ator . ▁High er ▁angles ▁of ▁solar ▁ill um ination ▁and ▁lower ▁view ing ▁angles ▁make ▁it ▁increasing ly ▁difficult ▁to ▁disc ern ▁top ographic ▁variations ▁to ▁the ▁west . ▁Many ▁ge olog ic ▁units ▁cannot ▁be ▁specifically ▁identified ▁because ▁of ▁unf av ou rable ▁view ing ▁geometry