Help Id'ing Receiving Postmark On 1868 Cover From US To Germany

Can anyone help with identifying the postmark on the back of this envelope? See the second image below. It is a CDS with the letters "AUSC" at the top. I believe the "4 9" below that stands for the date of September 4.

This cover started its journey in New Orleans on August 17, 1868. It arrived in New York City on August 22, 1868 where it was placed on a steamer to cross the Atlantic. After making a stop in England in a closed mail bag (I assume that was case based on my understanding of the US-North German Union Convention of 1867), it arrived at the Verviers-Cologne traveling post office on September 9, 1868. You can make out that date ("3 9") in the red postmark in the center lower-left.

The "AUSC" is likely a postal abbreviation associated with Bremen, but I would like to confirm that.

Thanks in advance!

Hi Captain,
a similar postmark here on card
311655396244

It's an abbreviation of AUSGABE. It's an acknowledgment of when the letter was received.

Aha! so it is AUSG
No wonder Askphil did not recognise my query AUSC

They have Ausgabe: issue, set or single.

Thank you much Germania!