Sorry but the question is not clear 
Are you asking:
IF you need to make the 0.5 C correction.
or
HOW to make the 0.5 C correction.
or
WHY a 0.5 C correction is necesary.
?
Sorry but the question is not clear Are you asking:
IF you need to make the 0.5 C correction.
or
HOW to make the 0.5 C correction.
or
WHY a 0.5 C correction is necesary.
?