When is night of Shaban?

[irum007]

Asalam alaykum,

I read on one of the websites that Allah descends to the lower heavens on the night of mid-Shaban and it is advisable to ask for forgiveness and other duas during the this time. Can one of your sisters or brothers please enlighten me and confirm if:

1) The date of mid-Shaban is 15th Shaban (i.e. 16th July 2011)
2) Are we supposed to fast on 16th July?

And my big question- when does the night of Shaban fall- is it the 14th of Shaban after Maghrib prayers until sunrise? Or is it the 15th of Shaban after Maghrib prayers? As Muslims, we know that a new day begins after Maghrib prayers so technically 14th Shaban after Maghrib will be 15th Shaban. But I'm not too sure about this- please help me.

Thank you!