Hi again Clive,
Just double checked with The Sky 6 and it is 5650 Mochihito-o.
If you are running any of the good planetarium programmes like The Sky etc you can download the current minor planet database of around 330,000 known minor planets and just reset the date and the time in your planetarium programme - if it is known then you will have it, if it is not then you have further investigation to do. This link will help (the download is a compressed 26meg file or unzipped about 73 meg).
http://www.cfa.harvard.edu/iau/MPCORB.html
I see Brendan has sent the Minor planet checker, you can use that or my link. Just do a search based on the time of your observation converted to decimal time. I.e. your first date 26th May at 9pm would be written in the checker as 2009 05 26.45 - where 26th is the day and the .45 comes from 2100hrs converted to UT = 1100hrs UT divided by 24 = .45
Put in the RA & DEC and do a search around the area - I did a 15 arc min search.
Hope this makes sense, by the way nice image!
PeterM.