New DX record on 500kHz WSPR

This evening, quite unexpectedly, I got a string of reports on 500kHz from OH1LSQ in KP03sd at an astounding distance of 1733km. To me these are amazing reports pushing my best DX on the band with just a few milliwatts ERP to new levels.  What surprises me is how well a very simple wire loop works as a TX antenna: the wire is just 1mm diameter, with a loop area of around 70m square with part of the loop on the ground buried in wet grass. I now believe almost anything is possible!