The Sony Xperia Sirius or Xperia D6503 has been spotted along with Xperia Z1 and the Xperia Z in the recent leak. The Xperia Sirius is assumed to be arriving at the MWC on 24th of this month which is less than 10 days from now.
What can be said from the images is that the smartphone has a very similar design alike the other flagship Xperia devices, hence we can even see the bezels at the top and bottom. The smartphone has been reported to sport a 5.2-inch display but it seems to be a very minor difference from the Xperia Z1.
We recently saw a support of 4k video recording leaked out and hence this gives a stronger speculation that the Xperia Sirius will have the same 20.7MP camera sensors like the Z1. The smartphone is believed to have a Snapdragon 800 SoC processor, 1080p resolution display and Android KitKat 4.4.