  In this paper, we describe an experiment measuring low-$Q^2$ elastic
electron-proton scattering using a newly developed cryogenic supersonic gas jet
target in the A1 three-spectrometer facility at the Mainz Microtron. We
measured the proton electric form factor within the four-momentum transfer
range of $0.01\le Q^2 \le 0.045(\text{GeV/c})^2$. The experiment showed
consistent results with the existing measurements. The data we collected
demonstrated the feasibility of the gas jet target and the potential of future
scattering experiments using high-resolution spectrometers with this gas jet
target.
