Title.. Hoping to find out when a historical tx went into the mempool. I'm aware this is transient data and not in the blockchain. However i'm pretty sure I remember in the old days explorers used to log it.
i would like to find a block explorer that logs the first time its node saw particular transactions in the mempool, as opposed to the first time they were in a block. ie: I would like to look up a tx and see how long it sat in the mempool before it was mined.