Air raid report West Wales 16/9/1940

On the night of 16th Sept 1940 a total of 14 bombs were dropped on a field near the Aberystwyth-Machynlleth road with one causing a crater 30' x 24' x 12' according to police reports. It was at 2155 and I am presuming that it had been intercepted or had mechanical issues and dropped its load before going on to it target. Liverpool was bombed that night, there would have been no targets around the bomb site. Police reports at the time suggest the plane flew very low over a local village - according to the local policeman, within revolver shooting range!

Any ideas what size Luftwaffe bombs would cause this size crater, 50 or 100kg?
What bomber would carry a load of 14 bombs? - I am thinking a Ju88 or a Do17 from Luftlotte 3 bases in Northern France/Belgium/Netherlands. I don't think the HE111 with the combination of bombs would be a likely option.
Where would I find information of combat reports for that night? If they exist.

Thanks for any help