
-As I recall, Astre is a name Yana Tobaso wrote down in her initial notes on Kirashitsuji as a possible name for ourciel. She had written several angel names. Astre is a name similar to one of the named angels, like Azriel, Cassiel, Raphael.
Ourciel was called Lord Sirius during the scene where he was framed for the music hall murders, and by the fortune teller in the prison carriage. He didn't confirm or deny it either time.
-For a few years, Tobaso created Christmas Greeting cards with OurCiel holding a multi-pointed blue star. It has to be some sort of message or clue, and it obviously points to Sirius, a blue star in the Canus Constellation and the brightest star in Earth's night sky. Sirius is a binary star system with two stars, an enormous blue star rotating around a tiny white star. The clue could mean several things, not necessarily his name.
The fact is, we don't know yet for certain what OurCiel's birth name is. To date, no specific name has been given in the manga.

Which chapter, right? lol http://www.mangago.zone/read-manga/kuroshitsuji/an/m_chapter-143/pg-1/

Here's Ciel holding Blue Star http://www.mangago.zone/home/album/79374/
I really like flashbacks but I'm still dying to know 'Ciel's' true name ( ̄∇ ̄")