We present contemporaneous HST WFPC2 and VLA observations of the symbiotic nova HM Sge .
We identify a number of discreet features at spatial scales smaller than \sim 0.1 arcsec embedded in the extended nebula , with radio and optical emission well correlated in the inner 1 arcsec .
For the first time we measure the positions of the binary components of a symbiotic star directly .
We estimate the projected angular binary separation to be 40 \pm 9 milli–arcsec , with the binary axis at position angle 130 ^ { \circ } \pm 10 ^ { \circ } .
The latter is consistent with previous estimates made by indirect methods .
The binary separation is consistent with a previous estimate of 50 au if the distance is 1250 \pm 280 pc .
Temperature and density diagnostics show two distinct regions in the surrounding nebula , with a cool wedge to the south–west .
An extinction map indicates the true interstellar extinction to be no more than E ( B–V ) = 0.35 .
This is consistent with a minimum distance of \sim 700 pc , but this would be reduced if there is a circumstellar contribution to the minimum in the extinction map .
The extinction map also suggests a patchy dust distribution .
We suggest that a southern concentration of dust and the south–west wedge are associated with the cool component wind .
Alternatively , the southern dust concentration is the cause of the cool wedge , as it shields part of the nebula from the hot component radiation field .