It appears that Blockchain started recording this only a month ago, at block 660900, or thereabouts.
I remember they were doing it long time ago, which actually caused some confusing specially because they also showed IP address of the "sender" (aka the node that send THEM the tx not the original node). It is probably a problem in their database, maybe they deleted all the old data. 
Topic: Does Electrum record the date a transaction was sent to the mempool? (Read 147 times)
January 25, 2021, 12:06:19 AM
January 24, 2021, 11:19:00 PM
As a side note of no consequence, during my attempt to find this transition I ran across a block for which I could not determine whether Blockchain was recording or not, https://www.blockchain.com/btc/block/660500. The block consists only of a coinbase. :/
There's actually more of that empty block, specially on the older days.The old ones were simply because there are no transaction in the miner's mempool, so they mined the block empty.
The latest are speculated that those were blocks that're mined seconds after the previous block,
like your example 660500: previous block height 660499 has the same timestamp as that empty block.
You might enjoy this discussion: Bitcoin's Empty Blocks Analaysis.
January 24, 2021, 10:25:28 PM
Ahem... you appear to be correct.
But only recently.
It appears that Blockchain started recording this only a month ago, at block 660900, or thereabouts.
As a side note of no consequence, during my attempt to find this transition I ran across a block for which I could not determine whether Blockchain was recording or not, https://www.blockchain.com/btc/block/660500. The block consists only of a coinbase. :/
And on another attempt, when surfing to a page of transactions included in a block by modifying the URL, I just coincidentally choose the last page of 211 exactly, on my first try.
But only recently.
It appears that Blockchain started recording this only a month ago, at block 660900, or thereabouts.
As a side note of no consequence, during my attempt to find this transition I ran across a block for which I could not determine whether Blockchain was recording or not, https://www.blockchain.com/btc/block/660500. The block consists only of a coinbase. :/
And on another attempt, when surfing to a page of transactions included in a block by modifying the URL, I just coincidentally choose the last page of 211 exactly, on my first try.
January 24, 2021, 05:04:03 PM
the closest I can think of would be the "received time" shown for a transaction on blockchain.com
The time listed there is the timestamp of the block.
Check TransID: 0753895afa2c2f76b6a383a4ec2fe8efa87c583588dcb5fe7b9154dd50b57680
Received Time: 2021-01-24 18:06
Block was: 667422
BlockTime was: 2021-01-24 18:56
Note: it's possible that for some transactions, blockchain.com might only see the transaction for the first time when it is included in a block... so you might get received time == block time... or it might be that the transaction was received a few seconds before the block was mined etc (as the timestamp is only to the nearest minute).
January 24, 2021, 04:01:23 PM
the closest I can think of would be the "received time" shown for a transaction on blockchain.com
The time listed there is the timestamp of the block.Bitcoin core seems to store the time it first saw the transaction...
It does appear that Bitcoin Core records the sent time of a transaction, which is great to know. Thank you. For the transactions for which I am currently looking for sent times I was using Electrum, unfortunately. January 24, 2021, 03:34:41 PM
Or is there an online service that has this information available?
I'm not sure if Electrum stores the time it was broadcast... the closest I can think of would be the "received time" shown for a transaction on blockchain.com:
But that is only indicative of the time that the transaction was (last) received by blockchain.com... it may have been dropped/rebroadcast etc...
Bitcoin core seems to store the time it first saw the transaction... but if the node isn't running, that "received time" may not be when it was first broadcast etc.
Why is the "broadcast" time important to you? What are you attempting to determine exactly?
January 24, 2021, 03:20:23 PM
... you should be able to see the time associated with it ...
There is no mention of a mempool or of a time associated with one.... you should be able to see ... the block height when it was signed.
How do I determine the time that the transaction was sent to the mempool from the block height? 
January 24, 2021, 01:55:05 PM
If information provided by the transaction is trustworthy, then it should be listed in the blockheight or blocktime on the transaction when it was sent. If you can get something similar to the advanced tab option in electrum (it might be right clicking the transaction and selecting an option like "view transaction") then you should be able to see the time associated with it or the block height when it was signed.
January 24, 2021, 01:37:56 PM
I would like to know the time a confirmed transaction was sent to the mempool. Does Electrum store this information? Or is there an online service that has this information available?
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