Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Team | Outgoing manager | Date of departure | Replaced by | Date of Appointment |
| --- | --- | --- | --- | --- |
| Hertha BSC | Karsten Heine | 19 May 2007 | Lucien Favre | 1 July 2007 |
| VfL Wolfsburg | Klaus Augenthaler | 19 May 2007 | Felix Magath | 1 July 2007 |
| Energie Cottbus | Petrik Sander | 23 September 2007 | Bojan Prašnikar | 28 September 2007 |
| Arminia Bielefeld | Ernst Middendorp | 10 December 2007 | Michael Frontzeck | 1 January 2008 |
| FC Schalke 04 | Mirko Slomka | 13 April 2008 | Mike Büskens Youri Mulder | 14 April 2008 |
Question:
When was the departure date when a manager was replaced by Bojan Prašnikar?
Answer:
23 September 2007