Referee Iain Brines has admitted he wrongly disallowed the goal which could have finished Celtic's title challenge.
Brines penalised Zander Diamond for handball seconds before the Aberdeen defender struck what would have been a last-minute equaliser at Celtic Park.
However, Brines has used the Scottish FA website to explain his mistake.
"Having had the opportunity to view the incident via television, I fully accept that I called this incident completely wrong," he said.
Celtic's 1-0 win moved them two points clear at the top of the table, although Rangers have played three games fewer.
The decision left Diamond and his colleagues enraged and the defender was critical of Brines after the game.
The referee has since told the 'whistleblower' section of the SFA's website: "From the angle I had adopted, I observed the Aberdeen player Diamond jump to meet the ball and I believed he used his hand to aid the ball's flight beyond him.
"Immediately I blew my whistle awarding a free-kick to Celtic.
"The majority of players reacted to the whistle by stopping - the exception being Diamond who placed the ball into the Celtic goal.
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"Having adopted the position I did, it didn't allow me to gain the best view of what happened during the incident.
"It is clear that the goal should not have been disallowed."
In a post-match interview that may land Diamond in hot water, the Aberdeen man said: "Saying I used my hand is an absolute joke and that sums him up.
"I thought he had a poor game.
"The decision is unbelievable. If that's one of Scotland's top officials, I think we're in trouble."
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